title: Salsolinol-a potential inhibitor of the gonadotropic axis in sheep during lactation.
abstract: This study tested the hypothesis that salsolinol, a derivative of dopamine, affects GnRH and LH secretion in lactating sheep. In the in vivo experiment, the structural analogue of salsolinol, 1-methyl-3,4-dihydroisoquinoline (1-MeDIQ), was infused into the infundibular nucleus-median eminence of sheep at the fifth wk of lactation to antagonize salsolinol's action. Simultaneously, cerebrospinal fluid from the third brain ventricle, to determine GnRH concentration, and plasma samples, to measure LH concentration, were collected. In the in vitro experiment, the anterior pituitary (AP) explants from weaned sheep were incubated in culture medium containing 2 doses of salsolinol, 20 and 100 μg/mL (S20 and S100, respectively). The concentration of LH in the collected media and relative expression of LHβ subunit messenger RNA in the AP explants were determined. No significant difference was found in mean GnRH concentration in response to 1-MeDIQ infusion, but both mean plasma LH concentration and LH pulse frequency increased significantly (P < 0.001 and P < 0.05, respectively) compared with those in controls. Significantly higher LH concentrations occurred during the first (P < 0.001), second (P < 0.001), and fourth (P < 0.05) h of 1-MeDIQ infusion. In the in vitro study, both the S20 and S100 doses of salsolinol caused a significant decrease in the mean medium LH concentration compared with that in the control (P < 0.01 and P < 0.001, respectively). Salsolinol had no effect on the relative LHβ subunit messenger RNA expression in the incubated tissue. In conclusion, salsolinol is a potential inhibitor of the secretory activity of the gonadotropic axis in lactating sheep, at least at the AP level. Although no significant changes in GnRH release were directly confirmed, an increase in the frequency of LH pulses does not allow to exclude the central action of salsolinol.
authors: Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jablonna, Poland.
authors: E
authors: E
authors: Marciniak
authors: Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jablonna, Poland.
authors: M
authors: M
authors: Hasiec
authors: Institute of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Szeged, Szeged, Hungary.
authors: F
authors: F
authors: Fülöp
authors: Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jablonna, Poland. Electronic address: t.misztal@ifzz.pl.
authors: T
authors: T
authors: Misztal
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects; D017077:Culture Media, Conditioned / Q000032:analysis; D005260:Female; D015870:Gene Expression; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000134:cerebrospinal fluid / Q000378:metabolism; D007546:Isoquinolines / Q000008:administration & dosage* / Q000037:antagonists & inhibitors; D007774:Lactation / Q000502:physiology*; D007986:Luteinizing Hormone / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000097:blood; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics; D008473:Median Eminence / Q000187:drug effects; D010900:Pituitary Diseases / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012756:Sheep / Q000502:physiology*; D046509:Tissue Culture Techniques
chemical_list: C486859:1-methyl-3,4-dihydroisoquinoline; D017077:Culture Media, Conditioned; D007546:Isoquinolines; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; C036617:salsolinol
keywords: Anterior pituitary; Cerebrospinal fluid; GnRH; LH; Lactation; Salsolinol