Effects of 6-hydroxydopamine on testosterone production by mouse leydig cells in vitro.
Increasing doses (15 to 1000 micrograms/ml) of 6-hydroxydopamine (6-OHDA) stimulated, then suppressed testosterone production by mouse leydig cells incubated for 3 h in vitro. The stimulating doses ranged between 50 and 100 micrograms/ml, with maximal effects occurring at 30 to 60 minutes after the start of the treatments. At doses of 500 micrograms/ml, 6-OHDA exhibited inhibitory effects. When added to leydig cell incubations together with stimulating doses of luteinising hormone (LH), 1-(3',4'-dihydroxyphenil)2-isopropylaminoethanol (L-isoproterenol) or 8-bromoadenosine 3':5'-cyclic monophosphate (8-Br-cAMP), 6-OHDA abolished the effects of the latter compounds. Prolactin and prostaglandin E2 (PGE2) inhibited the stimulating effects of 8-Br-cAMP but not LH. It is proposed that the actions of 8-OHDA affect intracellular sites yet to be identified, thereby inhibiting testosterone production by mouse Leydig cells. Some of the actions of 6-OHDA seem to be medicated via beta-adrenergic receptors as the latter abolishes the stimulatory effects of L-isoproterenol, a potent beta-adrenergic agonist. However, the inability of stimulatory doses of LH and 8-Br-cAMP to reverse the inhibitory effects of 6-OHDA point to the possibility that other actions of 6-OHDA may be relayed via a second messenger system separate from that involving cAMP.
Wango
E O
EO
Department of Animal Physiology, University of Nairobi, Kenya.
Odongo
H O
HO
Oduma
J
J
Oduor-Okelo
D
D
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D015232:Dinoprostone / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology; D008297:Male; D051379:Mice; D016627:Oxidopamine / Q000494:pharmacology*; D011388:Prolactin / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000096:biosynthesis*
D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D015124:8-Bromo Cyclic Adenosine Monophosphate; D013739:Testosterone; D016627:Oxidopamine; D011388:Prolactin; D007986:Luteinizing Hormone; D015232:Dinoprostone; D007545:Isoproterenol