Receptors for neuropeptides are induced by exogenous poly(A)+ RNA in oocytes from Xenopus laevis.
Receptors for the hormones vasopressin, angiotensin II, and thyrotropin-releasing hormone have been studied electrophysiologically in Xenopus laevis oocytes previously injected with poly(A)+ RNA from the respective receptor-containing tissues. The injected oocytes responded to the hormones by demonstrating oscillations in membrane currents as recorded by the voltage-clamp method. The response was dependent on the hormone concentrations and detectable between 5 and 1000 nM concentrations. Size fractionation of poly(A)+ RNA from the respective tissues showed that the mRNAs encoding the three hormone receptors were larger than 18S rRNA, suggesting a length of at least 2 kilobases. When vasopressin was added to the oocyte bath, an inward membrane current was generated in oocytes injected with rat poly(A)+ RNA from liver but not from kidney. This suggests that the V1-type (liver), not the V2-type (kidney), vasopressin receptor can be expressed and electrophysiologically identified in the oocyte. A V1-specific, but not a V2-specific, antagonist suppressed the vasopressin-dependent effect. Application of angiotensin II to liver poly(A)+ RNA-injected oocytes elicited oscillations in membrane current, indicating that these oocytes also expressed receptors for angiotension II; the antagonist [Sar1, O-methionyl-Tyr4]angiotensin II blocked this effect. Poly(A)+ RNA from tumor-derived GH3B6 cells, known to contain receptors for thyrotropin-releasing hormone, injected into oocytes induced receptors responding to thyrotropin-releasing hormone; the drug chlordiazepoxide suppressed the thyrotropin-releasing hormone response.
D000200:Action Potentials / Q000187:drug effects; D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D005260:Female; D005786:Gene Expression Regulation; D007473:Ion Channels / Q000187:drug effects; D008099:Liver / Q000032:analysis; D005810:Multigene Family; D009865:Oocytes; D011061:Poly A / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*; D051381:Rats; D011945:Receptors, Angiotensin / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D017483:Receptors, Vasopressin; D013973:Thyrotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D014667:Vasopressins / Q000037:antagonists & inhibitors / Q000494:pharmacology; D014982:Xenopus laevis
D057911:Angiotensin Receptor Antagonists; D007473:Ion Channels; D012333:RNA, Messenger; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D014667:Vasopressins; D000804:Angiotensin II; D011061:Poly A; D013973:Thyrotropin-Releasing Hormone