Dural Stimulation and Periorbital von Frey Testing in Mice As a Preclinical Model of Headache

Summary

The most notable symptom of migraine is severe head pain, and it is hypothesized that this is mediated by sensory neurons innervating the meninges. Here, we present a method to locally apply substances to the dura in a minimally invasive manner while using facial hypersensitivity as an output.

Abstract

The cranial meninges, comprised of the dura mater, arachnoid, and pia mater, are thought to primarily serve structural functions for the nervous system. For example, they protect the brain from the skull and anchor/organize the vascular and neuronal supply of the cortex. However, the meninges are also implicated in nervous system disorders such as migraine, where the pain experienced during a migraine is attributed to local sterile inflammation and subsequent activation of local nociceptive afferents. Of the layers in the meninges, the dura mater is of particular interest in the pathophysiology of migraines. It is highly vascularized, harbors local nociceptive neurons, and is home to a diverse array of resident cells such as immune cells. Subtle changes in the local meningeal microenvironment may lead to activation and sensitization of dural perivascular nociceptors, thus leading to migraine pain. Studies have sought to address how dural afferents become activated/sensitized by using either in vivo electrophysiology, imaging techniques, or behavioral models, but these commonly require very invasive surgeries. This protocol presents a method for comparatively non-invasive application of compounds on the dura mater in mice and a suitable method for measuring headache-like tactile sensitivity using periorbital von Frey testing following dural stimulation. This method maintains the integrity of the dura and skull and reduces confounding effects from invasive techniques by injecting substances through a 0.65 mm modified cannula at the junction of unfused sagittal and lambdoid sutures. This preclinical model will allow researchers to investigate a wide range of dural stimuli and their role in the pathological progression of migraine, such as nociceptor activation, immune cell activation, vascular changes, and pain behaviors, all while maintaining injury-free conditions to the skull and meninges.

Introduction

Migraine pain remains a major public health issue worldwide. The World Health Organization ranks it as the sixth-most prevalent disease in the world, afflicting just under 15% of the Earth's population¹ and causing a substantial socioeconomic burden on society^2,3. Treatment options and their efficacy have been suboptimal and only provide symptomatic relief and do not significantly modify pathophysiological events that underly migraine occurrence^4,5. The lack of treatment success is likely due to migraine being a multifactori....

Protocol

All procedures were conducted with prior approval of the institutional Animal Care and Use Committee at the University of Texas at Dallas. ICR (CD-1) (30-35 g) and C57/BL6 (25-30 g) mice aged 6-8 weeks were used in this study.

1. Dural infuser

1. Create the mouse infusers/injectors by modifying a commercially available internal cannula and infuser for unilateral injections with a non-metallic fused silica plastic cap that is adjustable and inserts into/extends below a 28 G guide cannu.......

Discussion

Maladaptive changes in the local nociceptive system in the dura are considered a key contributor to the headache phase of migraine attacks despite a lack of tissue injury^25,26. Here the study presents a method whereby minimally invasive stimulation of the dura can induce facial tactile hypersensitivity. Elucidating the mechanisms and events involved in dural nociceptor activation without causing damage to the cranium and tissues may more accurately reflect migrai.......

Materials

Name	Company	Catalog Number	Comments
4 oz Hot Paper Cups	Choice Paper Company	5004W	https://www.webstaurantstore.com/choice-4-oz-white-poly-paper-hot-cup-case/5004W.html
Absorbent Underpads	Fisherbrand	14-206-65	https://www.fishersci.com/shop/products/fisherbrand-absorbent-underpads-8/p-306048
C313I/SPC Internal 28 G cannula	P1 Technologies (formerly Plastics One)	8IC313ISPCXC	I.D. 18 mm, O.D. 35 mm
Gastight Model 1701 SN Syringes	Hamilton	80008	https://www.hamiltoncompany.com/laboratory-products/syringes/80008
Ismatec Pump Tubing, 0.19 mm	Cole-Palmer	EW-96460-10	https://www.coleparmer.com/i/ismatec-pump-tubing-2-stop-tygon-s3-e-lab-0-19-mm-id-12-pk/9646010
Stand with chicken wire	Custom		The galvanized steel chicken wire dimensions are 0.25 in. x 19-gauge
Testing Rack with individual  Chambers	Custom		Each chamber should have a division between each mouse and lids to contain the mouse. The chambers should also be large enough to hold a 4 oz. paper cup.
von Frey Filaments	Touch test/Stoelting	58011	https://www.stoeltingco.com/touch-test.html