Effects of arginine vasopressin and oxytocin on glucagon release from clonal α-cell line In-R1-G9: Involvement of V 1b receptors

• Published in: Life sciences (1973) Vol. 63; no. 21; pp. 1871 - 1878
• Main Authors: Yibchok-anun, Sirintorn, Hsu, Walter H.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 16.10.1998
• Subjects: arginine vasopressin; glucagon; oxytocin; pancreatic α-cells; V 1b receptor; V 1b receptor; glucagon; arginine vasopressin; oxytocin; pancreatic α-cells
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/S0024-3205(98)00463-9

Receptor antagonists were used to determine which receptor mediates the effect of arginine vasopressin (AVP) and oxytocin (OT) on glucagon release from hamster glucagonoma In-R1-G9 cells. Both AVP (10 −9–10 −6 M) and OT (10 −8–10 −5 M) increased glucagon release from In-R1-G9 cells in a concentration-dependent manner and AVP was ~30-fold more potent than OT in this aspect. The antagonists with potent V 1b receptor blocking activity, CL-4-84 (10 −9–10 −6 M), dP[Tyr(Me) 2]AVP and AO-2-44 (10 −8–10 −6 M), antagonized the effect of both AVP and OT in a concentration-dependent manner. Other receptor antagonists at 10 −6 M failed to block the effect of AVP and OT; these included a highly selective OT-receptor antagonist, L-366,948 and a V 1a V 2 receptor antagonist WK-3–6. However, these antagonists at higher concentrations (10 −5 and 10 −4 M) caused inhibition of AVP- and OT-induced glucagon release. The order of antagonistic potency was estimated as CL-4-84 ≈ dP[Tyr(Me) 2]AVP ≈ AO-2-44 > WK 3–6 > L366,948. d[D-3-Pal]VP (10 −8–10 −5 M), a V 1b receptor agonist, also increased glucagon release in a concentration-dependent manner, which was antagonized by dP[Tyr(Me) 2]AVP (10 −8-10 −6 M) and CL-4-84 (10 −9–10 −6 M), but not by WK-3–6 (10 −6 M) or L-366,948 (10 −6 M). Therefore, the stimulatory effects of both OT and AVP on glucagon release may be mediated by V 1b receptors, but not by V 1a, V 2 or OT receptors.