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Home / Equine Research Bank / Int J Mol Sci / Cannabinoid Receptors in the Horse Lateral Nucleus of the Am...
International journal of molecular sciences2025; 26(15); 7613; doi: 10.3390/ijms26157613

Cannabinoid Receptors in the Horse Lateral Nucleus of the Amygdala: A Potential Target for Ameliorating Pain Perception, Stress and Anxiety in Horses.

Abstract: The amygdala is composed of several nuclei, including the lateral nucleus which is the main receiving area for the input from cortical and subcortical brain regions. It mediates fear, anxiety, stress, and pain across species. Evidence suggests that the endocannabinoid system may be a promising target for modulating these processes. Cannabinoid and cannabinoid-related receptors have been identified in the amygdala of rodents, carnivores, and humans, but not in horses. This study aimed to investigate the gene expression of cannabinoid receptors 1 (CB1R) and 2 (CB2R), transient receptor potential vanilloid 1 (TRPV1), and peroxisome proliferator-activated receptor gamma (PPARγ) within the lateral nucleus of six equine amygdalae collected post mortem from an abattoir using quantitative real-time PCR, cellular distribution, and immunofluorescence. mRNA expression of CB1R and CB2R, but not TRPV1 or PPARγ, was detected. The percentage of immunoreactivity (IR) was calculated using ImageJ software. Cannabinoid receptor 1 immunoreactivity was absent in the somata but was strongly detected in the surrounding neuropil and varicosities and CB2R-IR was observed in the varicosities; TRPV1-IR showed moderate expression in the cytoplasm of somata and processes, while PPARγ-IR was weak-to-moderate in the neuronal nuclei. These findings demonstrate endocannabinoid system components in the equine amygdala and may support future studies on spp. molecules acting on these receptors.
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Publication Date: 2025-08-06 PubMed ID: 40806746PubMed Central: PMC12347058DOI: 10.3390/ijms26157613Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates the presence of cannabinoid receptors in the lateral nucleus of horse amygdalae and their potential role in influencing pain, stress, and anxiety responses in horses.

Introduction and Objective of the Research

  • The study seeks to further expand the knowledge about animal neuroanatomy and neurophysiology, particularly in equines.
  • The focus is on the lateral nucleus of the amygdala, one of the key nuclei associated with processing and regulating fear, anxiety, stress, and pain in several species.
  • The endocannabinoid system and its related receptors have been significantly linked with the modulation of these processes in several species such as rats, carnivores, and humans. Still, its existence in horses remains unexplored.
  • The primary aim of this research is to identify the expression of cannabinoid receptors 1 (CB1R) and 2 (CB2R) and other related receptors within the horse amygdala.

Methodology

  • Six horse amygdalae were procured post-mortem from an abattoir for the study.
  • The researchers employed quantitative real-time PCR, cellular distribution, and immunofluorescence techniques.
  • They looked into the gene expression of cannabinoid receptors CB1R and CB2R, transient receptor potential vanilloid 1 (TRPV1), and peroxisome proliferator-activated receptor gamma (PPARγ).
  • The extent of immunoreactivity (IR), a measure of how reactive an antigen is to an antibody, was calculated using ImageJ software.

Results

  • The results showed the presence of mRNA expression of cannabinoid receptors CB1R and CB2R in the studied samples, corroborating the existence of these receptors in horses.
  • However, the TRPV1 and PPARγ receptors did not exhibit any mRNA expression.
  • Immunoreactivity varied across the different receptors, with differing observed reactions to antigens across the tested receptors.
  • CB1R revealed strong detection in the surrounding neuropil and varicosities but was absent in the somata or cell body.
  • CB2R immunoreactivity was observed in varicosities, while TRPV1 showed moderate expression in both the somata and processes. PPARγ immunoreactivity was weak-to-moderate in the neuronal nuclei.

Conclusions

  • The results demonstrate the presence of endocannabinoid system components in the horse amygdala, marking an important discovery in equine anatomy and opening pathways to evaluate the potential impact on the modulation of fear, anxiety, stress, and pain in horses.
  • The findings may facilitate future studies focusing on how particular molecules interact with these receptors in horses.

Cite This Article

APA
Bombardi C, Salamanca G, Tagliavia C, Grandis A, Zamith Cunha R, Gramenzi A, De Silva M, Zannoni A, Chiocchetti R. (2025). Cannabinoid Receptors in the Horse Lateral Nucleus of the Amygdala: A Potential Target for Ameliorating Pain Perception, Stress and Anxiety in Horses. Int J Mol Sci, 26(15), 7613. https://doi.org/10.3390/ijms26157613

Publication

International journal of molecular sciences
ISSN: 1422-0067
NlmUniqueID: 101092791
Country: Switzerland
Language: English
Volume: 26
Issue: 15
PII: 7613

Researcher Affiliations

Bombardi, Cristiano
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.
Salamanca, Giulia
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.
  • Department of Translational Medicine and for Romagna, University of Ferrara, 40121 Ferrara, Italy.
Tagliavia, Claudio
  • Department of Veterinary Medicine, University of Teramo, 64100 Teramo, Italy.
Grandis, Annamaria
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.
Zamith Cunha, Rodrigo
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.
Gramenzi, Alessandro
  • Department of Veterinary Medicine, University of Teramo, 64100 Teramo, Italy.
De Silva, Margherita
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.
Zannoni, Augusta
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.
Chiocchetti, Roberto
  • Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, 40126 Bologna, Italy.

MeSH Terms

  • Animals
  • Horses
  • PPAR gamma / metabolism
  • PPAR gamma / genetics
  • Anxiety / metabolism
  • TRPV Cation Channels / metabolism
  • TRPV Cation Channels / genetics
  • Receptors, Cannabinoid / metabolism
  • Receptors, Cannabinoid / genetics
  • Pain Perception
  • Receptor, Cannabinoid, CB1 / metabolism
  • Receptor, Cannabinoid, CB1 / genetics
  • Amygdala / metabolism
  • Receptor, Cannabinoid, CB2 / metabolism
  • Receptor, Cannabinoid, CB2 / genetics
  • Male
  • Basolateral Nuclear Complex / metabolism

Grant Funding

  • No number / NBF Lanes, Milan, Italy

Conflict of Interest Statement

The authors declare no conflicts of interest.

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