Name: Author Spotlight: Insights, Innovations, and Future Avenues in Reproductive Neurocontrol
Uploaded: 2024-01-12T12:45:00
Description: Watch this Scientific Journal Video about Insights, Innovations, and Future Avenues in Reproductive Neurocontrol at JoVE.com

We would like to thank Dr. Kellie Breen Church, Mr. Michael Kreisman, and Ms. Jessica Jang for their contributions to collecting the data shown in the representative results. This work was supported by the National Institutes of Health (NIH) R00 HD104994 (R.B.M.).

All the procedures were approved by the Colorado State University (#3960) and University of California San Diego Institutional Animal Care and Use Committees, where the representative data were collected (S13235, PI Kellie Breen Church). Data from five adult female and two adult male C57/BL6 mice (9-16 weeks old) are depicted in the representative data section. Female mice were ovariectomized 3-4 weeks prior to ICV injection and blood collection as described previously7. Prior to experimentation, ...

Performing Intracerebroventricular Injection in Mice Using a Free-Hand Approach

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Here, a simple and effective means for making ICV injections in mice is described. Since this technique does not require a stereotaxic frame, this approach for the central delivery of drugs and experimental agents is accessible to more researchers. Additionally, this approach is relatively high throughput since the preparation and injection procedure can be performed quickly.
Since this procedure requires the manipulation of needles and a glass syringe by hand using approximate distances, it i...

The delivery of experimental agents, such as drugs1, viruses2, or cells3, to the brain is often necessary for neuroendocrine research. If the agent does not readily cross the blood-brain barrier or the experimental objective is to specifically test the central effects of the agent, it is important to have a reliable method for delivering injections into the brain. Moreover, injection into the intracerebroventricular (ICV) space provides the opportunity to distribute the agent widely in the brain and provides a large target area, thus increasing the likelihood of successful injection2. 
A common method for making ICV injections involves the placement of a permanent indwelling cannula. In this approach, a stereotaxic frame is necessary to position the commercially available or custom-made cannula, as the cannula is glued or cemented in place. Often, upon recovery, a supraphysiological dose of angiotensin II is administered through the cannula, and if drinking behavior is immediately observed, then the cannula is considered correctly placed4. This approach has many advantages, including the ability to perform long-term infusion and the ability to inject the same animal multiple times; additionally, if angiotensin II is employed, correct placement can be confirmed prior to the administration of experimental compounds. However, there are some limitations to placing a permanent cannula, including the requirement for expensive equipment (stereotaxic frame), the possibility of damage to the cannula after placement (e.g., mice can chew on the cannula of a cage mate), and the possibility of infections around the permanent cannula. Single ICV injections can be made with the use of a stereotaxic frame3, which, although effective, requires substantial exposure to anesthesia and, thus, may obscure some acute physiological and behavioral effects of the treatment. Additionally, the placement of mice in a stereotaxic frame requires substantial training to achieve stable placement and prevent the rupturing of the ear canals.
Here, an established method for making free-hand injections in mice is described. This method is based on previous reports5,6. The advantages of this technique are that it is simple, rapid, and does not require specialized equipment such as a stereotaxic frame. As described below, this procedure involves manipulating a glass syringe relative to landmarks on the mouse head to make the injections, which can be done rapidly and, thus, requires only a few minutes of gas anesthesia on the experimental day.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>18-gauge blunt needles</td>
			<td>SAI Infusion</td>
			<td>B18-150</td>
			<td></td>
		</tr>
		<tr>
			<td>18-gauge needles</td>
			<td>BD Medical</td>
			<td>305195</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol pads</td>
			<td>Fisher Scientific</td>
			<td>22-363-750</td>
			<td></td>
		</tr>
		<tr>
			<td>Bench pad</td>
			<td>Fisher Scientific</td>
			<td>14-206-62AC22</td>
			<td></td>
		</tr>
		<tr>
			<td>Betadine solution</td>
			<td>Fisher Scientific</td>
			<td>NC1696484</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Patterson Vet Supply</td>
			<td>07-892-5235</td>
			<td>Controlled substance</td>
		</tr>
		<tr>
			<td>Eyelube</td>
			<td>Fisher Scientific</td>
			<td>50-218-8442</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass syringe</td>
			<td>Hamilton</td>
			<td>7634-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Injection needle</td>
			<td>Hamilton</td>
			<td>7803-01</td>
			<td>27 gauge, Small Hub RN needle, point style: 4, Needle length: 10cm, Angle: 45</td>
		</tr>
		<tr>
			<td>Isoflurane&#160;&#160;</td>
			<td>Patterson Vet Supply</td>
			<td>07-893-8441</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane vaporizer</td>
			<td>Vet Equip</td>
			<td>V-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Laboratory Tape</td>
			<td>VWR</td>
			<td>89098-128</td>
			<td></td>
		</tr>
		<tr>
			<td>Medical grade oxygen</td>
			<td>Airgas</td>
			<td>OX USPEA</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Millipore-Sigma</td>
			<td>8.18715.1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline</td>
			<td>Fisher Scientific</td>
			<td>J67802.K2</td>
			<td></td>
		</tr>
		<tr>
			<td>PulsaR Software</td>
			<td>Open source, University of Otago</td>
			<td></td>
			<td>See ref 9</td>
		</tr>
		<tr>
			<td>Ruler</td>
			<td>Fisher Scientific</td>
			<td>12-00-152</td>
			<td></td>
		</tr>
		<tr>
			<td>Silastic tubing (0.040&#34; I.D.)</td>
			<td>DOW</td>
			<td>508-005</td>
			<td></td>
		</tr>
		<tr>
			<td>Silastic tubing (0.078&#34; I.D.)</td>
			<td>DOW</td>
			<td>508-009</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile saline</td>
			<td>VWR</td>
			<td>101320-574</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose&#160;</td>
			<td>Fisher Scientific</td>
			<td>S5-500</td>
			<td></td>
		</tr>
	</tbody>
</table>

free-hand intracerebroventricular injections in mice

The investigation of neuroendocrine systems often requires the delivery of drugs, viruses, or other experimental agents directly into the brains of mice. An intracerebroventricular (ICV) injection allows the widespread delivery of the experimental agent throughout the brain (particularly in the structures near the ventricles). Here, methods for making free-hand ICV injections in adult mice are described. By using visual and tactile landmarks on the heads of mice, injections into the lateral ventricles can be made rapidly and reliably. The injections are made with a glass syringe held in the experimenter&#39;s hand and placed at approximate distances from the landmarks. Thus, this technique does not require a stereotaxic frame. Furthermore, this technique requires only brief isoflurane anesthesia, which permits the subsequent assessment of mouse behavior and/or physiology in awake, freely behaving mice. Free-hand ICV injection is a powerful tool for the efficient delivery of experimental agents into the brains of living mice and can be combined with other techniques such as frequent blood sampling, neural circuit manipulation, or in vivo recording to investigate neuroendocrine processes.

Author Spotlight: Insights, Innovations, and Future Avenues in Reproductive Neurocontrol 

Free-Hand Intracerebroventricular Injections in Mice

We are interested in the neural control of reproductive function, particularly how the brain regulates the release of hormones that control the gonads, both in healthy conditions and in response to stress. The main advantage of this technique is that it is relatively simple and rapid. Delivering drugs into the lateral ventricle is a great way to cast a wide net in testing a signaling pathway to support more detailed follow-up experiments.There's still much to be learned about the neuroendocrine control of reproduction, including the molecular mechanisms for luteinizing hormone pulse generation, mechanisms for modulating pulse frequency during stress, and generation of the preovulatory LH surge. In the future, we are particularly interested in integrating disparate findings into models.

When performed successfully, this technique allows the rapid delivery of an experimental agent into the ventricular system. A luteinizing hormone (LH) pulse profile from an ovariectomized mouse that received an ICV injection of 3 &#181;L of sterile isotonic saline, the vehicle for many pharmacological compounds, is shown in Figure 2A. This example demonstrates that brief exposure to gas anesthesia and the injection of 3 &#181;L of fluid into the ventricular system alone did not alter the pul...

Watch this Scientific Journal Video about Insights, Innovations, and Future Avenues in Reproductive Neurocontrol at JoVE.com

Here, a simple and rapid approach for performing intracerebroventricular injections in mice using a free-hand approach (that is, without a stereotaxic device) is described.

The investigation of neuroendocrine systems often requires the delivery of drugs, viruses, or other experimental agents directly into the brains of mice. ...