title: Effects of suckling on serum prolactin levels and catecholamine concentrations and turnover in discrete brain regions.
abstract: The effects of suckling on serum prolactin levels and catecholamine concentrations and turnover were examined in several discrete brain regions. Turnover rates were assessed by using the synthesis inhibitor alpha-methyltyrosine (alpha-MT) in combination with microdissection techniques for the removal of individual brain regions and sensitive radioenzymatic assays for norepinephrine (NE) and dopaime (DA). Prolactin secretion was induced by mothers experiencing 6 h of pup removal with subsequent pup replacement. Suckling or the administration of alpha-MT to mothers resulted in a marked increase in circulating titers of prolactin. A decrease in steady-state NE concentrations in the anterior hypothalamus and a decrease in steady-state DA concentrations in the ventromedial nucleus were noted in suckled mothers. The comparison of relative rates of NE depletion after alpha-MT treatment revealed a suckling-induced increase in turnover in the ventromedial nucleus and a suckling-induced decrease in turnover in the anterior hypothalamus. Neither suckling nor alpha-MT treatment produced any changes in NE or DA turnover rates in the arcuate nucleus or median eminence. These findings demonstrate that suckling-induced activation of prolactin results in changes in noradrenergic processes in the ventromedial and anterior hypothalamic nuclei. This suggests an involvement of noradrenergic systems in suckling-induced prolactin release.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D005260:Female; D007774:Lactation; D008781:Methyltyrosines / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D011247:Pregnancy; D011388:Prolactin / Q000097:blood*; D051381:Rats; D014018:Tissue Distribution
chemical_list: D002395:Catecholamines; D008781:Methyltyrosines; D011388:Prolactin; D004298:Dopamine; D009638:Norepinephrine