title: Effects of melatonin treatment on Leydig cell activity in the testis of the frog Rana esculenta.
abstract: This study was conducted to verify the effect(s) of melatonin treatment on frog Leydig cells. Morphological observation after melatonin treatment indicates that many frog Leydig cells show degenerative changes (i.e. heterochromatic nuclei, loss of cellular adhesion) while in adjacent germinal tubules several Sertoli cells show heterochromatic nuclei, confirming the presence of a paracrine effect between interstitial and germinal compartments. The effect of melatonin on frog Leydig cell steroidogenesis was investigated in in vitro experiments; after 6 h of incubation melatonin severely inhibits both control and GnRH-induced testosterone secretion. In addition, in order to verify the effect of indolamine on frog Leydig cell activity, we investigated, by in situ hybridization, the presence of frog relaxin (fRLX, a transcript specifically expressed by these cells) in the testes of melatonin-injected animals after 48 h. fRLX signal completely disappeared from the testis of melatonin- injected frogs. The results of the present study indicate that melatonin treatment provokes Leydig cell morphological changes, blocks GnRH-antagonist-induced testosterone secretion and decreases fRLX expression. Taken together these results strongly indicate that melatonin acts on Leydig cells in the testis of the frog Rana esculenta.
authors.affiliation: Dipartimento di Medicina Sperimentale, Seconda Università degli Studi di Napoli, Naples, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: d'Istria
authors.forename: Ismene
authors.initials: I
authors.lastname: Serino
authors.forename: Gaia
authors.initials: G
authors.lastname: Izzo
authors.forename: Diana
authors.initials: D
authors.lastname: Ferrara
authors.forename: Gianluca
authors.initials: G
authors.lastname: De Rienzo
authors.forename: Sergio
authors.initials: S
authors.lastname: Minucci
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017403:In Situ Hybridization; D007211:Indoles / Q000494:pharmacology; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D011893:Rana esculenta / Q000033:anatomy & histology / Q000378:metabolism*; D012065:Relaxin / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000187:drug effects; D013256:Steroids / Q000096:biosynthesis; D013739:Testosterone / Q000378:metabolism
chemical_list: D007211:Indoles; D013256:Steroids; D013739:Testosterone; C067042:indolamine; D012065:Relaxin; D008550:Melatonin