Anandamide decreases the salivary secretion from the submandibular gland acting through cannabinoid receptors type 2

ELVERDIN JC.; FERNANDEZ SOLARI J; PRESTIFILIPPO JP; IRIBARNE M; SUBURO AM; RETTORI V; MCCANN SM

San Diego, California

Congreso; Experimental Biology 2005 with the XXXV International Congress of Physiological Science; 2005

International Union of Physiological Sciences

The secretion of saliva in the SMG is controlled by both divisions of the autonomic nervous system. Mammalian tissues contain at least two types of cannabinoid receptors, the CB1-r, located mainly in the nervous system, and the CB2-r, located mainly in peripheral tissues.  Both receptors are coupled to Gi and respond by inhibiting the activity of adenylyl cyclase. There are two main endocannabinioids, arachidonoyl ethanolamide (Anandamide, AEA) and 2-arachidonoyl glycerol (2-AG) that bind with high affinity to CB-r. It is known that marihuana use decreases saliva secretion, therefore the aim of this work was to study the effect of AEA on saliva secretion in a novel model of intraglandular injection. The localization of CB2-r in the acini of SMG were determined for first time by immunohistochemical studies. Salivary responses were determined in anaesthetized female Wistar rats by cannulating the ducts of the SMG, and injecting norepinephrine (NE) or metacholine (Mch) sequentially via the femoral vein. The SMGs were injected intraglandulary with 50 ìl of different drugs: 1) saline, 2) AEA (6x10-5M), 3) AEA + AM630 (6x10-4M, a specific antagonist of CB2-r, 4) AM630 alone. AEA decreased significantly the secretion of saliva stimulated by either NE or Mch. The AM630 blocked significantly the inhibitory effect of AEA in all treatments. We conclude that AEA decreases the secretion of saliva from SMG acting through CB2-r.