Alteration of Glucose Homeostasis in V1a Vasopressin Receptor-Deficient Mice

Abstract

Arginine-vasopressin (AVP) is known to be involved in maintaining glucose homeostasis, and AVP-resistance is observed in poorly controlled non-insulin-dependent diabetes mellitus subjects, resulting in a lowered plasma volume. Recently we reported that V1a vasopressin receptor-deficient (V1aR ؊/؊ ) mice exhibited a decreased circulating blood volume and hypermetabolism of fat accompanied with impaired insulin-signaling. Here we further investigated the roles of the AVP/V1a receptor in regulating glucose homeostasis and plasma volume using V1aR؊/؊ mice. The plasma glucose levels at the baseline or during a glucose tolerance test were higher in V1aR ؊/؊ than wild-type (WT) mice. Moreover, a hyperinsulinemic-euglycemic clamp revealed that the glucose infusion rate was significantly lower in V1aR ؊/؊ mice than in WT mice and that hepatic glucose production was higher in V1aR ؊/؊ mice than WT mice. In contrast to the increased hepatic glucose production, the liver glycogen content was decreased in the mutant mice. These results indicated that the mutant mice had impaired glucose tolerance. Furthermore, feeding V1aR ؊/؊ mice a high-fat diet accompanied by increased calorie intake resulted in significantly overt obesity in comparison with WT mice. In addition, we found that the circulating plasma volume and aldosterone level were decreased in V1aR ؊/؊ mice, although the plasma AVP level was increased. These results suggested that the effect of AVP on water recruitment was disturbed in V1aR ؊/؊ mice. Thus, we demonstrated that one of the AVP-resistance conditions resulting from deficiency of the V1a receptor leads to decreased plasma volume as well as impaired glucose homeostasis, which can progress to obesity under conditions of increased calorie intake. (Endocrinology 148: 2075-2084, 2007)A RGININE-VASOPRESSIN (AVP) is a neuropeptide hormone that is involved in diverse functions, including the regulation of osmotic homeostasis, vasoconstriction, and ACTH release. These physiological effects are mediated by three types of AVP receptors, designated as V1a, V1b, and V2 (1-3). The V1a receptor is widely expressed, whereas the V1b and V2 receptors are predominantly expressed in the anterior pituitary and the kidney, respectively (1-4). The functional role of the V1a receptor is considered to mediate vascular contraction (5), cellular proliferation (6), platelet aggregation (7), and glycogenolysis (1, 8). The V1b receptor stimulates ACTH and insulin release (9, 10). Both V1a and V1b receptors bind to the Gq protein and act through phosphatidylinositol hydrolysis to mobilize intercellular Ca 2ϩ (11,12). The V2 receptor is coupled with the Gs protein and stimulates adenylate cyclase to increase cellular cAMP, which results in the induction of an antidiuretic effect in the kidney (13).There have been several reports indicating the involvement of AVP in regulating the plasma glucose homeostasis. The plasma AVP level was increased in patients with insulindependent diabetes mellitus (IDDM) or non-IDDM (NIDDM) (14, 15), and treati...

Sex differences in the association between plasma copeptin and incident type 2 diabetes: the Prevention of Renal and Vascular Endstage Disease (PREVEND) study

“…The arginine vasopressin (AVP) stress-adaptation system has been shown to play a role in glucose homeostasis in both experimental and human studies [1,2]. Epidemiological studies investigating the prospective association between plasma AVP levels and risk of type 2 diabetes are scarce.…”

Aldosterone Requires Vasopressin V1a Receptors on Intercalated Cells to Mediate Acid-Base Homeostasis

“…Previously, we showed that the stimulation of V1aR in the macula densa is the first step of renin production and the deficient of V1aR in macula densa causes hyporeninemic hypoaldosteronism. 19,20 This study shows that the defect in urinary acid excretion in V1aR Ϫ/Ϫ mice is associated with functional defects in the vasopressin V1aR and subsequent changes in Rhcg, H-K-ATPase, and H-ATPase in the intercalated cells of the collecting ducts. Therefore, V1aR is essential not only for aldosterone production but also for tubular effects of aldosterone.…”

“…18 We have found that the deficient of V1aR causes hyporeninemic hypoaldosteronism. 19,20 Therefore, we investigated acid-base balance in mice lacking V1aR (V1aR Ϫ/Ϫ ). Furthermore, because the target site of aldosterone for acid-base regulation is the intercalated cells of the collecting duct, we established a new cell line of the intercalated cells.…”

First and third trimester serum concentrations of adropin and copeptin in gestational diabetes mellitus and normal pregnancy

“…In the population-based study conducted in Sweden, copeptin was an independent predicting factor for diabetes mellitus [21]. In an animal study, elevated AVP level as a result of AVP resistance at the level of V1aR was related to insulin resistance and diabetes mellitus [22,23]. However, a recent study of Yeung and coauthors (2014) investigates serum copeptin levels during pregnancy in relation to multiple pregnancy complications risk.…”