title: Corticotropin-releasing hormone stimulates adenylyl cyclase activity in the retinas of different animal species.
abstract: In the present study we investigated the presence of corticotropin-releasing hormone (CRH)-stimulated adenylyl cyclase activity in the retinas of different animal species. CRH significantly stimulated adenylyl cyclase activity in homogenates of calf, pig, rabbit and guinea pig retinas. The stimulatory effects were concentration-dependent with half-maximal responses occurring at 20-30 nM CRH. The enzyme activities increased by 37-80% at the maximal concentration of CRH (1 microM). On the other hand, adenylyl cyclase activities of chicken and pigeon retinas were poorly stimulated by CRH. In calf, pig and rabbit retinas, the CRH effect was completely antagonized by the CRH receptor antagonist alpha-helical CRH 9-41 and required the presence of GTP. The stimulatory response elicited by CRH was also found to be not additive with that produced by either vasoactive intestinal peptide or dopamine. These results provide evidence for the presence in retinas of different animal species of functional CRH receptors, an important criterion for the classification of CRH as a retinal neurotransmitter.
authors.affiliation: Department of Neuroscience University of Cagliari, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Olianas
authors.forename: V
authors.initials: V
authors.lastname: Loi
authors.forename: M
authors.initials: M
authors.lastname: Lai
authors.forename: E
authors.initials: E
authors.lastname: Mosca
authors.forename: P
authors.initials: P
authors.lastname: Onali
mesh_terms: D000262:Adenylyl Cyclases / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002645:Chickens; D010856:Columbidae; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006168:Guinea Pigs; D011817:Rabbits; D012160:Retina / Q000187:drug effects / Q000201:enzymology*; D013045:Species Specificity; D013268:Stimulation, Chemical; D013552:Swine; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D014660:Vasoactive Intestinal Peptide; D006160:Guanosine Triphosphate; D003346:Corticotropin-Releasing Hormone; D000262:Adenylyl Cyclases; D004298:Dopamine