85: Behavioural Characterisation of a Novel Rodent Model of Supraorbital Head Pain

Topic: Basic Science
Subtopic: Pain category (ICD-11), Chronic primary headache, , , Behavioral studies, , , , , ,

Background and Aims: Chronic head pain, including chronic migraine and cluster headaches, are debilitating and relentless for sufferers. The precise mechanisms underlying these conditions are still poorly understood, hindering the development of specific and effective treatments. Preclinical animal models are crucial in defining the circuitry of sensory sensitivity and emotional disturbances characteristic of these conditions. Pain with a supraorbital distribution is frequent in human clinical presentations, thus, we developed a rodent model of chronic head pain by manipulating the supraorbital nerve (SoN), a branch of the ophthalmic division of the trigeminal nerve that plays a critical role in transmitting head pain signals.

Methods: Female, Sprague Dawley rats (n=120) were arbitrarily assigned into supraorbital nerve chronic constriction injury (SoN-CCI); chronic localised inflammation (CLI); sham injury; or anaesthesia groups. They were further divided into endpoints of 2, 7, 14, 28, and 90-days post-surgery. Rats in the SoN-CCI group received a single ligature around the nerve, whereas surgery for the CLI group involved placing one piece of the ligature underneath the SoN. Behavioural testing was conducted both pre- and post-surgery. Behavioural responses to mechanical stimuli with a von Frey filament were evaluated, and spontaneous ‘pain’ behaviours were identified following exposure to bright light or sound.

Results: Our data demonstrated distinct and different behavioural repertoires in rats in the chronic localised inflammation (CLI) group when compared to the rats with supraorbital nerve constriction injury (SoN-CCI). Nine individual behaviours were identified following mechanical stimulation. Of these behaviours, clear differences were observed in head withdrawal, bite, and attack behaviours in the CLI group compared to the SoN-CCI group, across a 90-day post-surgery time-course. Further, these two groups displayed differences in rearing when exposed to bright light and SoN-CCI rats displayed a characteristic stress behaviour termed the ‘egg’ posture.

Conclusions: Our findings reveal that inflammatory and neuropathic injuries of the SoN generate distinct behavioural phenotypes across a 90-day time course. These differences were evident following mechanical stimulation and exposure to light, revealing sensory sensitivities that mirror those in chronic head pain conditions. By establishing this rodent model of chronic head pain, a detailed exploration of both peripheral and central, neural and non-neural changes underlying these behavioural differences can be initiated.

References: Nil

Presenting Author: Olivia I Davanzo
Submitting Author: Olivia Davanzo

Senior Author: Kevin A Keay

IASP 2026 Global Year theme of Neuropathic Pain: Yes

• Olivia I Davanzo: BSc (Hons) - Neuroscience, School of Medical Sciences, Faculty of Medicine and Health, University of Sydney; Brain and Mind Centre, University of Sydney
• Luke A Henderson: PhD - Neuroscience, School of Medical Sciences, Faculty of Medicine and Health, University of Sydney; Brain and Mind Centre, University of Sydney
• Kevin A Keay: PhD - Neuroscience, School of Medical Sciences, Faculty of Medicine and Health, University of Sydney; Brain and Mind Centre, University of Sydney