Endocannabinoid System Regulation in Pyometra-Affected and Healthy Canine Uteri

Area of Science:

• Veterinary Medicine
• Reproductive Biology
• Immunology

Background:

• Pyometra is a severe uterine infection in female dogs, involving significant immune and inflammatory responses.
• The endocannabinoid system (eCS), crucial for immune regulation and inflammation, has an unexamined role in canine uterine health and disease.

Purpose of the Study:

• To investigate the presence and regulation of endocannabinoid system (eCS) components within the canine uterus.
• To compare eCS expression in healthy (diestrus, anestrus) and pyometra-affected (closed-cervix, open-cervix) female dogs.

Main Methods:

• Quantification of serum progesterone, anandamide (AEA), and 2-arachidonylglycerol (2-AG).
• Assessment of uterine cannabinoid receptor 1 (CB1) and 2 (CB2) expression via real-time PCR and immunohistochemistry (IHC).
• Analysis of uterine tissues from 28 female dogs across four groups: closed-cervix pyometra, open-cervix pyometra, diestrus, and anestrus.

Main Results:

• Serum anandamide (AEA) levels were significantly lower in dogs with closed-cervix pyometra compared to anestrus.
• Cannabinoid receptors CB1 and CB2 were expressed in all uterine tissues studied.
• Immunohistochemistry revealed distinct localization patterns for CB1 and CB2 within different uterine compartments.

Conclusions:

• The canine uterus possesses a functional endocannabinoid system (eCS).
• Endocannabinoid system (eCS) modulation is associated with canine reproductive physiology and pyometra-induced inflammation.