Quantification of the effects of resperine on gonadotroph expression in the pituitary of goldfish (Carassius auratus).
In many teleosts, the control of gonadotropin II (or luteinizing hormone) secretion is under the dual control of stimulatory and inhibitory neuroendocrine factors. The principal stimulating factor is gonadotropin-releasing hormone and the main inhibitor is dopamine. Inhibiting the activities of dopamine by antidopaminergic drugs potentiates the actions of exogenous gonadotropin-releasing hormone analogs, resulting in a surge release of luteinizing hormone and ovulation and spawning in a number of different species. As the effects of blocking the inhibitory actions of dopamine on gonadotroph cytology have not been studied, goldfish were treated with 2, 4, 6 or 8 injections of reserpine (0.1 mg/kg body weight), at 48 h intervals, and the numbers of gonadotrophic cells studied at 48 h following last injection. After two injections, the number of gonadotrophic cells increased by 189% over controls; after four injections the increase was 234%; after six injections the increase was 259% and after eight injections, 288%. The results suggest that dopamine has an inhibitory influence on the numbers of gonadotrophs.
Osornio
Gabriela A
GA
Unidad de Morfología y Función, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, AP 314, Tlalnepantla, Edo. de México, México 54090, México.
Chavez
Monica
M
Peter
Richard E
RE
Cardenas
Rodolfo
R
D018759:Adrenergic Uptake Inhibitors / Q000008:administration & dosage*; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006054:Goldfish / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D006066:Gonads / Q000502:physiology* / Q000648:ultrastructure; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D012110:Reserpine / Q000008:administration & dosage*
D018759:Adrenergic Uptake Inhibitors; D007987:Gonadotropin-Releasing Hormone; D012110:Reserpine; D007986:Luteinizing Hormone; D004298:Dopamine