We are grateful to Raymond Sanchez at the University of Washington for his valuable help in manuscript editing and to M.Sc. Georgina Cort&#233;s and M.Sc. Cintia Javier for their technical support in the standardization of this technique. We are also grateful to the members of the vet services at Facultad de Estudios Superiores Zaragoza: MVZ. Adriana Altamirano, MVZ. Roman Hern&#225;ndez and MVZ. Dolores-Elizabeth Guzm&#225;n for the excellent maintenance and care of experimental animals. The experiments described in this protocol were supported by DGAPA-PAPIIT grant number: IN216015 and by CONACyT grant number: 236908 to Roberto Dom&#237;nguez. Carlos-Camilo Silva is a doctoral student from Programa de Doctorado en Ciencias Biom&#233;dicas, Universidad Nacional Aut&#243;noma de M&#233;xico (UNAM) and is supported by the Consejo Nacional de Ciencia y Tecnolog&#237;a (Grant number: 294555).

Procedures involving animals were approved by the Ethics Committee of Facultad de Estudios Superiores Zaragoza, UNAM. This institution operates in strict accordance with the Mexican rules for animal handling, Official Norm: NOM-062-ZOO-1999, which agrees with international guidelines.
1. Construction of bilateral cannulas
<ol>
	<li>Extract the stainless-steel shaft from the hub of two 23 G hypodermic needles using pressure tweezers and then remove any remaining glue using a scalpel blade.</l...

This article describes a method to transiently inactivate, at any given time, a discrete region in the brain of awake and unrestrained rats. A simple method to track their estrous cycle and assess ovulation is also provided. This protocol allows a straightforward analysis of the contribution of specific brain regions to the mechanisms that drive ovulation by comparing the ovulatory outcome of TTX-treated animals with that of vehicle-treated ones. With the exception of the stereotaxic instrument and the microinjection pum...

Ovulation is the process by which one or more mature oocytes are released from the ovaries once every estral/menstrual cycle. As all mammalian species depend on the production of gametes to breed, the understanding of the mechanisms that regulate ovulation has a huge impact in areas ranging from biomedicine, the livestock industry and the maintenance of endangered species. Ovulation is regulated by the hypothalamic-pituitary-ovarian axis, which involves several hypothalamic and extra-hypothalamic areas, the gonadotropes in the anterior pituitary and the theca and granulosa cells that, along with the oocytes, form the ovarian follicles inside the ovaries1.
Ovarian follicles grow, develop and eventually ovulate in response to the tonic and phasic secretion of the follicle-stimulating hormone and the luteinizing hormone, the two gonadotropins secreted by the gonadotropes. The pattern of gonadotropin secretion is pivotal for proper follicular development and ovulation and it is regulated by the gonadotropin-releasing hormone (GnRH)1,2. This neuropeptide is synthesized by neurons scattered throughout the basal diencephalon and then secreted to the portal vasculature that links the hypothalamus and the anterior pituitary. The secretory activity of the GnRH-neurons is in turn modulated by synaptic input arising from diverse brain structures. These structures convey information about the state of the external and internal environment of the organism including the availability of food, the length of the photoperiod and the concentration of hormones in the blood. In this sense, they shape the reproductive pattern of each species and the specific roles of such structures must be determined in order to properly understand the mechanisms governing ovulation. As an example, it has been shown that the fluctuation in estradiol levels during the estrous cycle regulates the secretion of GnRH; however, GnRH-neurons does not express the estradiol receptor isoform needed to detect such changes. Two populations of neurons expressing these receptors are located in the rostral periventricular region of the third ventricle and in the arcuate nucleus, respectively, and stablish synapses with GnRH-neurons. There is evidence to suggest that these neurons interpret the concentration of estradiol and then stimulate the activity of GnRH-neurons by releasing kisspeptin, a potent inductor of GnRH secretion3.
Experiments involving thermic or chemical lesions, as well as mechanical deafferentation, allowed researchers to determine the involvement of several brain structures in the regulation of ovulation4,5,6,7,8,9,10,11,12. These experiments, however, have the disadvantage of being invasive and traumatic, requiring several days of recovery before evaluating the effects of the treatment, impeding the analysis of the acute effects of the treatment. In addition, they permanently affect the targeted areas and disrupt other physiological processes in the long term. Due to these problems, the results of these experiments are usually obscured by the homeostatic compensatory mechanisms in the animal&#180;s body and extracting accurate information about the temporal regulatory dynamics in which the area is involved is rather difficult.
The microinjection of drugs that transiently disrupt the activity of neurons through guide cannulas is a suitable alternative that surpasses the disadvantages mentioned above. The cannulas can be placed in any brain region by a stereotaxic surgery, allowing the researcher to start the drug treatment after the confounding effects of the surgery disappear. The timed microinjection of the drugs allows researchers to test hypotheses regarding the contribution of the region to a particular step of the process and can be performed in awake restrained or free-moving animals. A variety of drugs including local anesthetics, agonists, antagonists, inverse agonists and biological toxins such as tetrodotoxin (TTX) can be microinjected into the region of interest at specific times.
TTX is a biological toxin synthesized by bacteria living in the body of the pufferfish as well as other vertebrates and invertebrates. TTX silences neural activity through the selective and transient blockade of sodium channels, which results in the inhibition of sodium-dependent action potentials. In the presence of TTX, cells experience an alteration in the depolarization phase and thus are not excitable but remain alive. The blocking effect of TTX is explained by its molecular composition: a guanidinium group is able to pass through the extracellular aspect of the sodium channel, but the rest of the molecule cannot pass due to its size, so it is stuck and blocks the channel13,14,15,16,17. The mechanism of action of the TTX allowed its use as a tool to study the nervous system both in vitro and in vivo. Intracerebral injection of this toxin has been used to study the role of discrete brain areas in several processes like memory retention18, sleep and arousal19, place recognition20, spatial navigation21, drug abuse22, thermoregulation23, development of schizophrenia24, sexual behavior25 and regulation of ovulation26 among others. In this protocol we describe the effects on ovulation of the transient inactivation of hypothalamic nuclei by TTX microinjection in awake and unrestrained rats.

<table>
	<tbody>
		<tr>
			<td>10 &#956;L Hamilton syringes</td>
			<td>Hamilton</td>
			<td>80314</td>
			<td></td>
		</tr>
		<tr>
			<td>21 G x 1&#34; stainless steel hypdermic needle</td>
			<td>BD</td>
			<td>305165</td>
			<td></td>
		</tr>
		<tr>
			<td>23 G x 1&#34; stainless steel hypdermic needle</td>
			<td>BD</td>
			<td>305145</td>
			<td></td>
		</tr>
		<tr>
			<td>30 G x 1/2&#34; stainless steel hypdermic needle</td>
			<td>BD</td>
			<td>305106</td>
			<td></td>
		</tr>
		<tr>
			<td>Artificial cerebrospinal fluid</td>
			<td>BASi</td>
			<td>MD-2400</td>
			<td></td>
		</tr>
		<tr>
			<td>Bone trimer</td>
			<td>Fine Science Tools</td>
			<td>16152-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Burr for micro drill</td>
			<td>Fine Science Tools</td>
			<td>19007-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Clipper</td>
			<td>Wahl</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cut-off disc</td>
			<td>Dremel</td>
			<td>SM5010</td>
			<td></td>
		</tr>
		<tr>
			<td>Cutting tweezers</td>
			<td>Truper</td>
			<td>17367</td>
			<td></td>
		</tr>
		<tr>
			<td>Cyanocrylate glue</td>
			<td>Kola loka</td>
			<td>K-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Dental cement</td>
			<td>Nic Tone</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Enrofloxasin</td>
			<td>Senosiain</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Eosin</td>
			<td>Sigma</td>
			<td>E4009</td>
			<td></td>
		</tr>
		<tr>
			<td>Estereoscope</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Extra fine Bonn scissors</td>
			<td>Fine Science Tools</td>
			<td>14084-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Face mask</td>
			<td>Lanceta HG</td>
			<td>60036</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe Forceps</td>
			<td>Fine Science Tools</td>
			<td>11050-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Hematoxilin</td>
			<td>Sigma</td>
			<td>H3136</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemostats</td>
			<td>Fine Science Tools</td>
			<td>13008-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot bead sterilizer</td>
			<td>Fine Science Tools</td>
			<td>18000-45</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Sigma</td>
			<td>320331</td>
			<td></td>
		</tr>
		<tr>
			<td>Hypromelose artificial tears</td>
			<td>Sophia Labs</td>
			<td>8950015</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Pisa Agropecuaria</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Meloxicam</td>
			<td>Aranda</td>
			<td>1183</td>
			<td></td>
		</tr>
		<tr>
			<td>Microinjection pump</td>
			<td>KD Scientific</td>
			<td>788380</td>
			<td></td>
		</tr>
		<tr>
			<td>Monomer</td>
			<td>Nic Tone</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mototool</td>
			<td>Dremel</td>
			<td>3000</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitrile gloves</td>
			<td>Lanceta HG</td>
			<td>69028</td>
			<td></td>
		</tr>
		<tr>
			<td>Non-Rupture Ear Bars</td>
			<td>David Kopf Instruments</td>
			<td>855</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-L lysine</td>
			<td>Sigma</td>
			<td>P4707</td>
			<td></td>
		</tr>
		<tr>
			<td>Povidone-iodine</td>
			<td>Dermo Dine</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Povidone-iodine with soap</td>
			<td>Germisin espuma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pressure tweezers</td>
			<td>Truper</td>
			<td>17371</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat anesthesia mask</td>
			<td>David Kopf Instruments</td>
			<td>Model 906</td>
			<td></td>
		</tr>
		<tr>
			<td>Saline solution</td>
			<td>PISA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel</td>
			<td>Fine Science Tools</td>
			<td>10004-13</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel blade</td>
			<td>Fine Science Tools</td>
			<td>10015-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium pentobarbital</td>
			<td>Pisa Agropecuaria</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Standard electrode holder</td>
			<td>David Kopf Instruments</td>
			<td>1770</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless steel wire</td>
			<td>American Orthodontic</td>
			<td>856-612</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxic apparatus</td>
			<td>David Kopf Instruments</td>
			<td>Model 900LS</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Sissors</td>
			<td>Fine Science Tools</td>
			<td>14001-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Teflon connectors</td>
			<td>Basi</td>
			<td>MD-1510</td>
			<td></td>
		</tr>
		<tr>
			<td>Teflon tubing</td>
			<td>Basi</td>
			<td>MF-5164</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrodotoxin</td>
			<td>Alomone labs</td>
			<td>T-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Vaporizer</td>
			<td>Kent scientific</td>
			<td>VetFlo</td>
			<td></td>
		</tr>
	</tbody>
</table>

unraveling the role of discrete areas of the rat brain in the regulation of ovulation through reversible inactivation by tetrodotoxin microinjections

Many experimental approaches have been used for studying the role of the brain in the regulation of ovulation. Examples include the lesion and deafferentation of neuronal groups, which are both invasive methods that permanently impair the integrity of the target area. These methods are accompanied by collateral effects that can affect the analysis of acute and temporal regulatory mechanisms. The stereotaxic implantation of guide cannulas aimed at specific brain regions, followed by a recovery period, allows researchers to microinject different drugs after the disappearance of the undesired effects of the surgery. Tetrodotoxin has been used to determine the roles of several brain areas in diverse physiological processes because it transiently inhibits the sodium-dependent action potentials, thus blocking all neural activity in the target region. This protocol combines this method with strategies for the assessment of the estrous cycle and ovulation to reveal the role of discrete brain regions in the regulation of ovulation at particular times of any given stage of the estrous cycle. Awake and unrestrained rats (Rattus norvegicus) were used to avoid the blocking effects that anesthetics and stress hormones exert on ovulation. This protocol can be easily adapted to other species, brain targets and pharmacological agents to study different physiological processes. Future improvements to this method include the design of a microinjection system using glass capillaries of small diameter instead of guide cannulas. This will reduce the amount of tissue damaged during the implantation and decrease the spread of the infused drugs outside the target area.

The protocol described above was tested by evaluating the effects of a single TTX or vehicle (artificial cerebrospinal fluid; ACSF) microinjection into one of two different nuclei known to be involved in the regulation of ovulation in the rat: the suprachiasmatic and the arcuate nucleus. The suprachiasmatic nucleus was chosen since it contains the central circadian pacemaker in mammals. It is involved in the regulation of cyclic events as the secretion of gonadotropins. The arcuate nucleus was chosen because it contains ...

Watch this Scientific Journal Video about Unraveling the Role of Discrete Areas of the Rat Brain in the Regulation of Ovulation through Reversible Inactivation by Tetrodotoxin Microinjections at JoVE.

Unraveling the Role of Discrete Areas of the Rat Brain in the Regulation of Ovulation through Reversible Inactivation by Tetrodotoxin Microinjections

This protocol describes the construction of a low-cost microinjection system, its stereotaxic implantation into deep-brain structures and the procedure for timed microinjections of tetrodotoxin in awake and unrestrained rats. The goal is to reveal the participation of hypothalamic structures in the regulation of ovulation by inhibiting their neural activity.

Many experimental approaches have been used for studying the role of the brain in the regulation of ovulation. Examples include the lesion and ...

This protocol allows researchers to explore the nuclei of the neuronal circuits that regulates ovulation in female mammals at specific times of their estrous cycle.This technique can be adapted to study any process on the regulation of the brain in any species.Also they can less art fabricator in the lab lowering the overall cost.Demonstrating this procedure will be Montserrat Bola

unraveling-role-discrete-areas-rat-brain-regulation-ovulation-through

Research

JoVE Journal

Neuroscience

Brain Imaging Investigation of the Neural Correlates of Emotion Regulation

The ability to control/regulate emotions is an important coping mechanism in the face of emotionally stressful situations. Although significant progress has been made in understanding conscious/deliberate emotion regulation (ER), less is known about non-conscious/automatic ER and the associated neural correlates. This is in part due to the problems inherent in the unitary concepts of automatic and conscious processing1. Here, we present a protocol that allows investigation of the neural correlates of both deliberate and automatic ER using functional magnetic resonance imaging (fMRI). This protocol allows new avenues of inquiry into various aspects of ER. For instance, the experimental design allows manipulation of the goal to regulate emotion (conscious vs. non-conscious), as well as the intensity of the emotional challenge (high vs. low). Moreover, it allows investigation of both immediate (emotion perception) and long-term effects (emotional memory) of ER strategies on emotion processing. Therefore, this protocol may contribute to better understanding of the neural mechanisms of emotion regulation in healthy behaviour, and to gaining insight into possible causes of deficits in depression and anxiety disorders in which emotion dysregulation is often among the core debilitating features.

We present a protocol that allows investigation of the neural correlates of deliberate and automatic emotion regulation, using functional magnetic resonance imaging. This protocol can be used in healthy participants, both young and older, as well as in clinical patients.

The ability to control/regulate emotions is an important coping mechanism in the face of emotionally stressful situations. Although significant progress ...

Optimized Analysis of DNA Methylation and Gene Expression from Small, Anatomically-defined Areas of the Brain

Exposure to diet, drugs and early life adversity during sensitive windows of life 1,2 can lead to lasting changes in gene expression that contribute to the display of physiological and behavioural phenotypes. Such environmental programming is likely to increase the susceptibility to metabolic, cardiovascular and mental diseases 3,4.
DNA methylation and histone modifications are considered key processes in the mediation of the gene-environment dialogue and appear also to underlay environmental programming 5. In mammals, DNA methylation typically comprises the covalent addition of a methyl group at the 5-position of cytosine within the context of CpG dinucleotides.
CpG methylation occurs in a highly tissue- and cell-specific manner making it a challenge to study discrete, small regions of the brain where cellular heterogeneity is high and tissue quantity limited. Moreover, because gene expression and methylation are closely linked events, increased value can be gained by comparing both parameters in the same sample.
Here, a step-by-step protocol (Figure 1) for the investigation of epigenetic programming in the brain is presented using the 'maternal separation' paradigm of early life adversity for illustrative purposes. The protocol describes the preparation of micropunches from differentially-aged mouse brains from which DNA and RNA can be simultaneously isolated, thus allowing DNA methylation and gene expression analyses in the same sample.

A streamlined workflow to study DNA methylation and gene expression changes upon early-life stress is shown. Starting from maternal separation of newborn mice and isolation of discrete brain tissues, we represent a protocol to simultaneously isolate DNA and RNA from brain tissue punches for subsequent bisulfite sequencing and RT-PCR analysis.

Exposure to diet, drugs and early life adversity during sensitive windows of life 1,2 can lead to lasting changes in gene expression that contribute to ...

Stereotaxic Surgery for Excitotoxic Lesion of Specific Brain Areas in the Adult Rat

Many behavioral functions in mammals, including rodents and humans, are mediated principally by discrete brain regions. A common method for discerning the function of various brain regions for behavior or other experimental outcomes is to implement a localized ablation of function. In humans, patient populations with localized brain lesions are often studied for deficits, in hopes of revealing the underlying function of the damaged area. In rodents, one can experimentally induce lesions of specific brain regions.
Lesion can be accomplished in several ways. Electrolytic lesions can cause localized damage but will damage a variety of cell types as well as traversing fibers from other brain regions that happen to be near the lesion site. Inducible genetic techniques using cell-type specific promoters may also enable site-specific targeting. These techniques are complex and not always practical depending on the target brain area. Excitotoxic lesion using stereotaxic surgery, by contrast, is one of the most reliable and practical methods of lesioning excitatory neurons without damaging local glial cells or traversing fibers.
Here, we present a protocol for stereotaxic infusion of the excitotoxin, N-methyl-D-aspartate (NMDA), into the basolateral amygdala complex. Using anatomical indications, we apply stereotaxic coordinates to determine the location of our target brain region and lower an injection needle in place just above the target. We then infuse our excitotoxin into the brain, resulting in excitotoxic death of nearby neurons. While our experimental subject of choice is a rat, the same methods can be applied to other mammals, with the appropriate adjustments in equipment and coordinates.
This method can be used on a variety of brain regions, including the basolateral amygdala1-6, other amygdala nuclei6, 7, hippocampus8, entorhinal cortex9 and prefrontal cortex10. It can also be used to infuse biological compounds such as viral vectors1, 11. The basic stereotaxic technique could also be adapted for implantation of more permanent osmotic pumps, allowing more prolonged exposure to a compound of interest.

Targeted ablation of specific brain region(s) by infusion of an excitotoxin using stereotaxic coordinates is described. This technique could also be adapted for infusion of other chemicals into the rat brain.

Many behavioral functions in mammals, including rodents and humans, are mediated principally by discrete brain regions. A common method for discerning the ...

Analysis of Gene Expression Changes in the Rat Hippocampus After Deep Brain Stimulation of the Anterior Thalamic Nucleus

Deep brain stimulation (DBS) surgery, targeting various regions of the brain such as the basal ganglia, thalamus, and subthalamic regions, is an effective treatment for several movement disorders that have failed to respond to medication. Recent progress in the field of DBS surgery has begun to extend the application of this surgical technique to other conditions as diverse as morbid obesity, depression and obsessive compulsive disorder. Despite these expanding indications, little is known about the underlying physiological mechanisms that facilitate the beneficial effects of DBS surgery. One approach to this question is to perform gene expression analysis in neurons that receive the electrical stimulation. Previous studies have shown that neurogenesis in the rat dentate gyrus is elicited in DBS targeting of the anterior nucleus of the thalamus1. DBS surgery targeting the ATN is used widely for treatment refractory epilepsy. It is thus of much interest for us to explore the transcriptional changes induced by electrically stimulating the ATN. In this manuscript, we describe our methodologies for stereotactically-guided DBS surgery targeting the ATN in adult male Wistar rats. We also discuss the subsequent steps for tissue dissection, RNA isolation, cDNA preparation and quantitative RT-PCR for measuring gene expression changes. This method could be applied and modified for stimulating the basal ganglia and other regions of the brain commonly clinically targeted. The gene expression study described here assumes a candidate target gene approach for discovering molecular players that could be directing the mechanism for DBS.

The mechanism underlying the therapeutic effects of Deep Brain Stimulation (DBS) surgery needs investigation. The methods presented in this manuscript describe an experimental approach to examine the cellular events triggered by DBS by analyzing the gene expression profile of candidate genes that can facilitate neurogenesis post DBS surgery.

Deep brain stimulation (DBS) surgery, targeting various regions of the brain such as the basal ganglia, thalamus, and subthalamic regions, is an effective ...

Utilizing Combined Methodologies to Define the Role of Plasma Membrane Delivery During Axon Branching and Neuronal Morphogenesis

During neural development, growing axons extend to multiple synaptic partners by elaborating axonal branches. Axon branching is promoted by extracellular guidance cues like netrin-1 and results in dramatic increases to the surface area of the axonal plasma membrane. Netrin-1-dependent axon branching likely involves temporal and spatial control of plasma membrane expansion, the components of which are supplied through exocytic vesicle fusion. These fusion events are preceded by formation of SNARE complexes, comprising a v-SNARE, such as VAMP2 (vesicle-associated membrane protein 2), and plasma membrane t-SNAREs, syntaxin-1 and SNAP25 (synaptosomal-associated protein 25). Detailed herein isa multi-pronged approach used to examine the role of SNARE mediated exocytosis in axon branching. The strength of the combined approach is data acquisition at a range of spatial and temporal resolutions, spanning from the dynamics of single vesicle fusion events in individual neurons to SNARE complex formation and axon branching in populations of cultured neurons. This protocol takes advantage of established biochemical approaches to assay levels of endogenous SNARE complexes and Total Internal Reflection Fluorescence (TIRF) microscopy of cortical neurons expressing VAMP2 tagged with a pH-sensitive GFP (VAMP2-pHlourin) to identify netrin-1 dependent changes in exocytic activity in individual neurons. To elucidate the timing of netrin-1-dependent branching, time-lapse differential interference contrast (DIC) microscopy of single neurons over the order of hours is utilized. Fixed cell immunofluorescence paired with botulinum neurotoxins that cleave SNARE machinery and block exocytosis demonstrates that netrin-1 dependent axon branching requires SNARE-mediated exocytic activity.

Light microscopy techniques coupled with biochemical assays elucidate the involvement of SNARE-mediated exocytosis in netrin-dependent axon branching. This combination of techniques permits identification of molecular mechanisms controlling axon branching and cell shape change.

During neural development, growing axons extend to multiple synaptic partners by elaborating axonal branches. Axon branching is promoted by extracellular ...

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous system. SC-selective genetic manipulation in living animals is a powerful technique for studying the molecular and cellular mechanisms of SC myelination and demyelination in vivo. While knockout/knockin and transgenic mice are powerful tools for studying SC biology, these methods are costly and time consuming. Viral vector-mediated transgene introduction into the sciatic nerve is a simpler and less laborious method. However, viral methods have limitations, such as toxicity, transgene size constraints, and infectivity restricted to certain developmental stages. Here, we describe a new method that allows selective transfection of myelinating SCs in the rodent sciatic nerve using electroporation. By applying electric pulses to the sciatic nerve at the site of plasmid DNA injection, genes of interest can be easily silenced or overexpressed in SCs in both neonatal and more mature animals. Furthermore, this in vivo electroporation method allows for highly efficient simultaneous expression of multiple transgenes. Our novel technique should enable researchers to efficiently manipulate SC gene expression, and facilitate studies on SC development and function.

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

Here, we present an in vivo technique for gene transfer to Schwann cells (SCs) in the rodent sciatic nerve. This simple technique is useful for investigating signaling mechanisms involved in the development and maintenance of myelinating SCs.

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous ...

Sublimation of DAN Matrix for the Detection and Visualization of Gangliosides in Rat Brain Tissue for MALDI Imaging Mass Spectrometry

Sample preparation is key for optimal detection and visualization of analytes in Matrix-assisted Laser Desorption/Ionization (MALDI) Imaging Mass Spectrometry (IMS) experiments. Determining the appropriate protocol to follow throughout the sample preparation process can be difficult as each step must be optimized to comply with the unique characteristics of the analytes of interest. This process involves not only finding a compatible matrix that can desorb and ionize the molecules of interest efficiently, but also selecting the appropriate matrix deposition technique. For example, a wet matrix deposition technique, which entails dissolving a matrix in solvent, is superior for desorption of most proteins and peptides, whereas dry matrix deposition techniques are particularly effective for ionization of lipids. Sublimation has been reported as a highly efficient method of dry matrix deposition for the detection of lipids in tissue by MALDI IMS due to the homogeneity of matrix crystal deposition and minimal analyte delocalization as compared to many wet deposition methods 1,2. Broadly, it involves placing a sample and powdered matrix in a vacuum-sealed chamber with the samples pressed against a cold surface. The apparatus is then lowered into a heated bath (sand or oil), resulting in sublimation of the powdered matrix onto the cooled tissue sample surface. Here we describe a sublimation protocol using 1,5-diaminonaphthalene (DAN) matrix for the detection and visualization of gangliosides in the rat brain using MALDI IMS.

A protocol for the sublimation of DAN matrix onto rat brain tissue for the detection of gangliosides using MALDI Imaging Mass Spectrometry is presented.

Sample preparation is key for optimal detection and visualization of analytes in Matrix-assisted Laser Desorption/Ionization (MALDI) Imaging Mass ...

Personalized Needles for Microinjections in the Rodent Brain

Microinjections have been used for a long time for the delivery of drugs or toxins within specific brain areas and, more recently, they have been used to deliver gene or cell therapy products. Unfortunately, current microinjection techniques use steel or glass needles that are suboptimal for multiple reasons: in particular, steel needles may cause tissue damage, and glass needles may bend when lowered deeply into the brain, missing the target region. In this article, we describe a protocol to prepare and use quartz needles that combine a number of useful features. These needles do not produce detectable tissue damage and, being very rigid, ensure reliable delivery in the desired brain region even when using deep coordinates. Moreover, it is possible to personalize the design of the needle by making multiple holes of the desired diameter. Multiple holes facilitate the injection of large amounts of solution within a larger area, whereas large holes facilitate the injection of cells. In addition, these quartz needles can be cleaned and re-used, such that the procedure becomes cost-effective.

We describe here a protocol for microinjection in the rodent brain that uses quartz needles. These needles do not produce detectable tissue damage and ensure reliable delivery even in deep regions. Moreover, they can be adapted to research needs by personalized designs and can be re-used.

Microinjections have been used for a long time for the delivery of drugs or toxins within specific brain areas and, more recently, they have been used to ...

Recording Synaptic Plasticity in Acute Hippocampal Slices Maintained in a Small-volume Recycling-, Perfusion-, and Submersion-type Chamber System

Even though experiments on brain slices have been in use since 1951, problems remain that reduce the probability of achieving a stable and successful analysis of synaptic transmission modulation when performing field potential or intracellular recordings. This manuscript describes methodological aspects that might be helpful in improving experimental conditions for the maintenance of acute brain slices and for recording field excitatory postsynaptic potentials in a commercially available submersion chamber with an outflow-carbogenation unit. The outflow-carbogenation helps to stabilize the oxygen level in experiments that rely on the recycling of a small buffer reservoir to enhance the cost-efficiency of drug experiments. In addition, the manuscript presents representative experiments that examine the effects of different carbogenation modes and stimulation paradigms on the activity-dependent synaptic plasticity of synaptic transmission.

This protocol describes the stabilization of the oxygen level in a small volume of recycled buffer and methodological aspects of recording activity-dependent synaptic plasticity in submerged acute hippocampal slices.

Even though experiments on brain slices have been in use since 1951, problems remain that reduce the probability of achieving a stable and successful ...

Translational Brain Mapping at the University of Rochester Medical Center: Preserving the Mind Through Personalized Brain Mapping

The Translational Brain Mapping Program at the University of Rochester is an interdisciplinary effort that integrates cognitive science, neurophysiology, neuroanesthesia, and neurosurgery. Patients who have tumors or epileptogenic tissue in eloquent brain areas are studied preoperatively with functional and structural MRI, and intraoperatively with direct electrical stimulation mapping. Post-operative neural and cognitive outcome measures fuel basic science studies about the factors that mediate good versus poor outcome after surgery, and how brain mapping can be further optimized to ensure the best outcome for future patients. In this article, we describe the interdisciplinary workflow that allows our team to meet the synergistic goals of optimizing patient outcome and advancing scientific understanding of the human brain.

This article provides an overview of a multi-modal brain mapping program designed to identify regions of the brain that support critical cognitive functions in individual neurosurgery patients.

The Translational Brain Mapping Program at the University of Rochester is an interdisciplinary effort that integrates cognitive science, neurophysiology, ...