Automated detection of squint as a sensitive assay of sex-dependent calcitonin gene–related peptide and amylin-induced pain in mice

Rea, Brandon J.; Davison, Abigail; Ketcha, Martin-Junior; Smith, Kylie J.; Fairbanks, Aaron M.; Wattiez, Anne‐Sophie; Poolman, Pieter; Kardon, Randy H.; Russo, Andrew F.; Sowers, Levi P.

doi:10.1097/j.pain.0000000000002537

Cited by 18 publications

(26 citation statements)

References 31 publications

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“…The grimace scale was developed to evaluate spontaneous pain expression in mice ( 50 ). Our laboratory found that orbital tightening, or squint, is the principal component of mouse grimace score ( 51 ) and has developed an automated video-based squint assay to measure spontaneous pain ( 48 ). Taking advantage of this sensitive automated squint platform, we asked whether mice squint after CGRP injection in the MN.…”

Section: Resultsmentioning

confidence: 99%

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CGRP Administration Into the Cerebellum Evokes Light Aversion, Tactile Hypersensitivity, and Nociceptive Squint in Mice

et al. 2022

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The neuropeptide calcitonin gene-related peptide (CGRP) is a major player in migraine pathophysiology. Previous preclinical studies demonstrated that intracerebroventricular administration of CGRP caused migraine-like behaviors in mice, but the sites of action in the brain remain unidentified. The cerebellum has the most CGRP binding sites in the central nervous system and is increasingly recognized as both a sensory and motor integration center. The objective of this study was to test whether the cerebellum, particularly the medial cerebellar nuclei (MN), might be a site of CGRP action. In this study, CGRP was directly injected into the right MN of C57BL/6J mice via a cannula. A battery of tests was done to assess preclinical behaviors that are surrogates of migraine-like symptoms. CGRP caused light aversion measured as decreased time in the light zone even with dim light. The mice also spent more time resting in the dark zone, but not the light, along with decreased rearing and transitions between zones. These behaviors were similar for both sexes. Moreover, significant responses to CGRP were seen in the open field assay, von Frey test, and automated squint assay, indicating anxiety, tactile hypersensitivity, and spontaneous pain, respectively. Interestingly, CGRP injection caused significant anxiety and spontaneous pain responses only in female mice, and a more robust tactile hypersensitivity in female mice. No detectable effect of CGRP on gait was observed in either sex. These results suggest that CGRP injection in the MN causes light aversion accompanied by increased anxiety, tactile hypersensitivity, and spontaneous pain. A caveat is that we cannot exclude contributions from other cerebellar regions in addition to the MN due to diffusion of the injected peptide. These results reveal the cerebellum as a new site of CGRP actions that may contribute to migraine-like hypersensitivity.

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Section: Resultsmentioning

confidence: 99%

“…This assay is to evaluate spontaneous pain by measuring the right-eye pixel areas recorded by a camera. Mice were acclimated to a customized collar restraint to reduce stress induced by restraint as well as struggle or head movement as described previously ( 48 ). C57BL/6J mice underwent acclimation for 20 min per session for three sessions.…”

Section: Methodsmentioning

confidence: 99%

CGRP Administration Into the Cerebellum Evokes Light Aversion, Tactile Hypersensitivity, and Nociceptive Squint in Mice

et al. 2022

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show abstract

“…This assay is to evaluate spontaneous pain by measuring the right-eye pixel areas recorded by a camera. Mice were acclimated to a customized collar restraint to reduce stress induced by restraint as well as struggle or head movement as described previously (81). C57BL/6J mice underwent acclimation for 20 min per session for three sessions.…”

Section: Automated Squint Assaymentioning

confidence: 99%

“…The grimace scale was developed to evaluate spontaneous pain expression in mice (84). Our laboratory found that orbital tightening, or squint, is the principal component of mouse grimace score (85) and has developed an automated video-based squint assay to measure spontaneous pain (81). Taking advantage of this sensitive automated squint platform, we asked whether mice squint after CGRP injection in the MN.…”

Section: Injection Of Cgrp Into the Mn Induced Squinting Behavior Primarily In Female Micementioning

confidence: 99%

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CGRP Administration into the Cerebellum Evokes Migraine-like Behaviors Predominately in Female Mice

Duong

Rea

Waite

et al. 2022

Preprint

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The neuropeptide calcitonin gene-related peptide (CGRP) is a major player in migraine pathophysiology. Previous preclinical studies demonstrated that intracerebroventricular administration of CGRP caused migraine-like behaviors in mice, but the sites of action in the brain remain unidentified. The cerebellum has the most CGRP binding sites in the central nervous system and is increasingly recognized as both a sensory and motor integration center. The objective of this study was to test whether the cerebellum, particularly the medial cerebellar nuclei (MN), might be a site of CGRP action. In this study, CGRP was directly injected into the right MN of C57BL/6J mice via a cannula. A battery of behavioral tests was done to assess migraine-like behaviors. CGRP caused light aversion measured as decreased time in the light zone even with dim light. The mice also spent more time resting in the dark zone, but not the light, along with decreased rearing and transitions between zones. These behaviors were similar for both sexes. In contrast, significant responses to CGRP were seen only with female mice in the open field assay, von Frey test, and automated squint assay, indicating anxiety, tactile hypersensitivity, and spontaneous pain, respectively. In male mice, the responses had the same trend as females but did not reach statistical significance. No detectable effect of CGRP on gait was observed in either sex. These results suggest that CGRP in the MN causes light aversion in males, while in females, light aversion is accompanied by increased anxiety, tactile hypersensitivity, and spontaneous pain. A caveat is that we cannot exclude contributions from other cerebellar regions in addition to the MN due to diffusion of the injected peptide. These results reveal the cerebellum as a new site of CGRP actions that may contribute to migraine pathophysiology and possibly its prevalence in females.

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The photic blink reflex as an index of photophobia

Hackley,

Johnson

2023

Biological Psychology

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Automated detection of squint as a sensitive assay of sex-dependent calcitonin gene–related peptide and amylin-induced pain in mice

Abstract: An automated facial detection and eye tracking program can measure pain caused by formalin hind paw injection or migraine-inducing compounds in mice. Calcitonin gene–related peptide and amylin induce significant squint behavior responses that are more predominant in female mice.

Cited by 18 publications

References 31 publications

CGRP Administration Into the Cerebellum Evokes Light Aversion, Tactile Hypersensitivity, and Nociceptive Squint in Mice

CGRP Administration Into the Cerebellum Evokes Light Aversion, Tactile Hypersensitivity, and Nociceptive Squint in Mice

CGRP Administration into the Cerebellum Evokes Migraine-like Behaviors Predominately in Female Mice

The photic blink reflex as an index of photophobia

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