|Zenor, Bianca - PURDUE UNIVERSITY|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: June 7, 1996
Publication Date: N/A
Technical Abstract: Cattle and pigs possess cannabinoid receptors in their central nervous system. However, the physiological relevance of these receptors has not been determined. The objective of this study was to determine the physiological effects of in vivo activation of the cannabinoid receptor in calves. Holstein steers (n=4) were fitted with indwelling jugular cannulae. On selected days during a 3 month period, blood samples were drawn every 10 min for 90 min. Then one of the three cannabinoid compounds (anandamide, 15 mg; methanandamide, 10 and 15 mg; or WIN 55212-2, 5 and 10 mg) or vehicle control was infused intravenously through the cannula. Blood sampling then continued every 10 min for an additional 210 min. Cortisol concentrations were determined in serum by RIA. For each animal, the six samples collected following cannabinoid infusion was compared to the six samples following the control infusion. Respiration rate and body temperature were also monitored throughout the bleeding periods. Followin the control infusion, serum cortisol averaged 2.1 ng/mL - not different than preinfusion values (p>.10). Serum cortisol was elevated (p<.05) following treatment with anandamide (37.2 ng/mL), WIN 55212-2 (19.5 ng/mL), 10 mg methanandamide (18.3 ng/mL), and 15 mg methanandamide (58.3 ng/mL). Immediately following cannabinoid infusion, but not following control, a rapid increase in respiration rate was observed, while no changes in rectal temperatures were observed. These results demonstrate that stimulation of the cannabinoid receptor produces physiological changes including activation of the cortisol-releasing pathway. It appears likely that the endogenous cannabinoid pathway is an integral part of the physiological stress response in calves.