title: Effects of leptin and leptin fragments on corticosterone secretion and growth of cultured rat adrenocortical cells.
abstract: Compelling evidence indicates that leptin, acting via specific receptors (Ob-Ra and Ob-Rb) modulates adrenocortical-cell secretion. However, the results are controversial, inasmuch as either secretagogue or antisecretagogue effects have been reported. Hence, we decided to study the effects of a 96-h incubation with leptin and leptin fragments 116-130, 150-167, 138-167, 93-105, 22-56 and 26-39 (10(-8) and 10(-6) M) on the secretion and growth of cultured rat adrenocortical cells. Reverse transcription-polymerase chain reaction showed that control cultures expressed both Ob-Ra and Ob-Rb isoforms. As expected, ACTH (10(-8) M) raised corticosterone secretion and lowered proliferation rate of cultured cells. Native leptin elicited ACTH-like effects, while fragment 116-130 was ineffective. Leptin fragments 150-167 and 26-39 stimulated corticosterone production, and fragments 138-167 and 22-56 inhibited it. Fragment 93-105 exerted a dose-dependent biphasic effect on corticosterone secretion (i.e. stimulation and inhibition at the concentration of 10(-8) and 10(-6) M, respectively). Leptin fragment 26-39 enhanced proliferation of cultured cells, while fragments 138-167 and 22-56 were ineffective. Fragments 150-167 and 93-105 displayed proliferogenic and antiproliferogenic effects at the concentration of 10(-8) and 10(-6) M, respectively. Taken together, these findings allows us to conclude that native leptin and its fragments interact differently with Ob-Rs or interact with different Ob-R isoforms, thereby variously modulating secretion and growth of cultured rat adrenocortical cells.
authors.affiliation: Department of Histology and Embryology, School of Medicine, PL-60781 Poznan, Poland.
authors.forename: Ludwik K
authors.initials: LK
authors.lastname: Malendowicz
authors.forename: Raffaella
authors.initials: R
authors.lastname: Spinazzi
authors.forename: Cinzia
authors.initials: C
authors.lastname: Tortorella
authors.forename: Gastone G
authors.initials: GG
authors.lastname: Nussdorfer
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Ziolkowska
authors.forename: Marcin
authors.initials: M
authors.lastname: Rucinski
mesh_terms: D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003345:Corticosterone / Q000378:metabolism*; D006801:Humans; D020738:Leptin / Q000494:pharmacology*; D051379:Mice; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D015383:Zona Fasciculata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015384:Zona Glomerulosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015385:Zona Reticularis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D020738:Leptin; D010446:Peptide Fragments; D011994:Recombinant Proteins; D003345:Corticosterone