Pain and Sociality Neural Networks: NOP Agonist Attenuates Hyperactivation in Migraine

In Neuropsychopharmacology they showed that in the classic mouse model of migraine (nitroglycerin injection), not only pain sensitivity suffers, but also social behavior. A selective NOP receptor agonist (Ro 64-6198) eliminated both mechanical allodynia and social impairments; the effect was partially eliminated by the NOP antagonist SB-612111, which confirms the point of application. Mapping of activated neurons (TRAP2/Ai9) revealed a surge in activity in the cingulate cortex, amygdala, hippocampus, hypothalamus, periaqueductal gray matter (in females), and in the caudal nucleus of the trigeminal nerve (in both sexes) - and all this was normalized by Ro 64-6198.

Background

• Migraine is a major contributor to lost health. GBD estimates that cases have increased significantly between 1990 and 2021; migraine remains the leading cause of years lived with disability (especially in women under 50).
• The nitroglycerin (NTG) model is a validated method for inducing "migraine-like" symptoms in animals and humans. In mice, NTG reproduces hypereralgesia/allodynia and a range of behavioral features; the effect is partially reversed by known anti-migraine drugs. The model is widely used for primary screening of therapeutic targets.
• The NOP/nociceptin system is a promising target in pain. The NOP receptor (nociceptin/orphanin FQ) modulates pain transmission and stress responses; agonists have demonstrated analgesic effects in models of neuropathic and inflammatory pain, potentially with lower “opioid” risks. Preclinically, Ro 64-6198 has already been shown to reduce NTG-induced allodynia and photosensitivity in mice, and the effect is blocked by the antagonist SB-612111. This supported the idea of testing NOP agonists specifically in the context of migraine.
• Migraine is not only about pain: social functions are affected. A number of behavioral studies on NTG models have described disturbances in social interaction/affective shifts; therefore, it is important to test targets that can affect both pain and social behavior.
• Mapping activated neurons: TRAP2/Ai9. Activity-dependent tagging (TRAP2) technology allows us to “tag” neurons activated during an event (such as a seizure) and then visualize their distribution across brain structures—a handy tool for seeing how a drug dampens hyperactivated networks.
• What was missing before this work. Despite the signals that NOP agonism reduces the pain manifestations of NTG migraine, there was no systematic analysis of social behavior and its comparison with the map of brain hyperactivation in both sexes. The new article in Neuropsychopharmacology closes precisely this gap.

What did they do?

• Migraine-like symptoms were induced in male and female mice by a single administration of nitroglycerin (NTG).
• Mechanical allodynia (periorbital and paw) and social tests (three-chamber paradigm, partner novelty) were assessed.
• Mice were given the selective NOP receptor agonist Ro 64-6198; some animals received the concomitant antagonist SB-612111 to test specificity.
• Using the TRAP2/Ai9 reporter system, neurons activated after NTG were labeled and the activation “map” was compared with and without Ro 64-6198.

What did they find?

• NTG produced both pain and social deficits in both sexes. Ro 64-6198 reversed these effects; NOP blockade partially restored the deficits.
• Analgesia was gender dependent: Ro 64-6198 clearly blocked allodynia in males; in females the analgesic effect was weaker, but the drug eliminated social disturbances in both sexes.
• At the brain level, NTG included pain- and social-related networks (ACC, amygdala, hippocampus, hypothalamus, PAG in females, trigeminal nucleus in both sexes). This hyperactivation was reduced by Ro 64-6198.
• The authors have uploaded the raw data to RepOD (Icm UW) for re-analysis.

Why is this important?

• Migraine is not just about pain. Social "disability" - from avoiding contacts to dropping out of work - is one of the most painful aspects for patients. The work provides a biological link between migraine-like pain, social symptoms and NOP signaling, showing that these links can be hit with a single target.
• The NOP (nociceptin/orphanin FQ) system is a “fourth” opioid lineage capable of modulating pain, stress, and sociality. Animal data support it as a candidate target for migraine therapy outside the serotonin axis (triptans/gapants).

How it can work

Ro 64-6198 activates NOP receptors, attenuating pain transmission in the trigeminovascular circuit and calming limbic-cortical circuits involved in anxiety/social avoidance. Reduction of NTG-induced hyperactivation in the ACC, amygdala, hippocampus, and PAG is a direct neural correlate of the observed behavioral improvement.

Restrictions

• This is a mouse model of acute migraine. It is valid, but does not describe the whole clinical picture (aura, chronic migraine, comorbid anxiety/depression).
• Ro 64-6198 is an investigational drug; its safety/efficacy in humans has not been demonstrated.
• The pronounced gender dependence of analgesia suggests that the clinic will have to take into account gender and hormonal status.

What's next?

• To test NOP agonists in chronic migraine models and in combination with current standards (triptans, CGRP antagonists).
• Look for biomarkers of response (e.g. ACC/amygdala activation profiles in fMRI in humans).
• To test whether NOP modulation reduces social maladjustment in migraine patients - not just pain intensity.

Source: Mudgal, A., Wronikowska-Denysiuk, O., Martinez, M. et al. Ro 64-6198, a selective NOP receptor agonist attenuates social impairments associated with NTG-induced migraine pain. Neuropsychopharmacol. (2025). https://doi.org/10.1038/s41386-025-02187-z