Dopaminergic actions of parathyroid hormone in the rat medial basal hypothalamus in vitro.
Parathyroid hormone (PTH) modulates dopamine (DA) metabolism in the rat medial basal hypothalamus (MBH) in vivo. Direct effects of PTH on MBH DA metabolism were therefore investigated in vitro. Incubation of rat MBHs for 60 min with 10(-7)-10(-5) M human PTH1-34 consistently reduced the tissue DA content and increased the DOPAC (dihydroxyphenylacetic acid) to DA ratio. This ratio was further increased in tissues incubated in 10(-5) M PTH1-34, as a result of an increase in DOPAC content. The tissue content of DOPAC and DA was unaffected by 10(-9) M PTH. The serotonin (5HT) content of the MBH was reduced by 10(-5) M PTH1-34, but concentrations of 5HT, 5-hydroxyindolacetic acid, and norepinephrine were otherwise unaffected by 10(-9)-10(-5) M PTH1-34. Concentrations of DA in the incubation media were reduced after exposure to 10(-6) or 10(-5) M PTH1-34. The uptake of 3H-labelled DA by incubated tissues was also reduced by 10(-6) M PTH1-34, as was the metabolism of 3H-labelled DA into tissue and media DOPAC. Monoamine oxidase (MAO) activities A and B were significantly increased after the incubation of the MBH with 10(-6) or 10(-5) M PTH1-34. These results further demonstrate neuromodulatory actions of PTH on dopaminergic neurons within the rat MBH in vitro, and suggest neural and/or neuroendocrine roles of PTH of central or peripheral origin.
Harvey
S
S
Department of Physiology, University of Alberta, Edmonton, Canada.
Hayer
S
S
Sloley
B D
BD
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D007033:Hypothalamus, Middle / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008995:Monoamine Oxidase / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism
D010281:Parathyroid Hormone; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D008995:Monoamine Oxidase; D004298:Dopamine