Effects of arginine vasopressin deficiency on innate immunity in the rat

Immune and vascular endothelial cells possess arginine vasopressin (AVP) receptors. AVP is an important stimulating/regulatory hormone in acquired immunity, whereas its role on innate immunity (INIM) is not well known. Neurointermediate pituitary lobectomy (NIL) in the rat causes permanent low AVP serum levels. Here, we investigate the AVP and INIM relationship in NIL rats (3 weeks after surgeries) subject to INIM tests: Phagocytic index (PI) (peritoneal macrophages (Mθ) erytrophagocytosis), and Skin Evans blue extravasation-histamine doses-response test. In the Study 1, NIL group was compared against Intact control (IC), sham operated (SHAM) and anterior pituitary lobectomysed (AL) groups. In the study 2, NIL group was compared against IC, NIL+desmopressin (a synthetic analog of AVP) and IC+conivaptan (antagonist of V1a-V2 AVP receptors) groups. Results: Study 1 showed that as compared with the IC and AL groups, PI was significant decreased in NIL animals. In the Evans blue extravasation-histamine test s...