The aim of the present study was to clarify the effects of hypothalamic dopamine (DA) on salsolinol (SAL)-induced prolactin (PRL) release in goats. The PRL-releasing response to an intravenous (i.v.) injection of SAL was examined after treatment with augmentation of central DA using carbidopa (carbi) and L-dopa in male goats under 8-h (8h light, 16h dark) or 16-h (16h light, 8h dark) photoperiod conditions. The carbi and L-dopa treatments reduced basal PRL concentrations in the 16-h photoperiod group (P<0.05), while a reduction was not observed in the 8-h photoperiod group. The mean basal plasma PRL concentration in the control group for the 8-h photoperiod was lower than that for the 16-h photoperiod (P<0.05). SAL significantly stimulated the release of PRL promptly after the injection in both the 8- and 16-h photoperiod groups (P<0.05). PRL-releasing responses for the 16-h photoperiod were greater than those for the 8-h photoperiod (P<0.05). The carbi and L-dopa treatments blunted SAL-induced PRL release in both the 8- and 16-h photoperiods (P<0.05). These results indicate that hypothalamic DA blunts the SAL-induced release of PRL in male goats, regardless of the photoperiod, which suggests that both SAL and DA are involved in regulating the secretion of PRL in goats.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)