Increase of rat serum prolactin by adenosine analogs and their blockade by the methylxanthine aminophylline.
The administration of the stable adenosine analogs N6-[(R)-methyl-2-phenylethyl]adenosine (R-PIA; 0.01-1.0 mg/kg i.p.) and 1-(6-amino-9H-purin-9-yl)-1-deoxy-N-ethyl-beta-D-ribofuronamide (NECA; 0.01-1.0 mg/kg i.p.) caused a dose-related (NECA) or biphasic (R-PIA) increases in rat serum prolactin. The S-isomer of PIA was inactive up to 4 mg/kg i.p. The methylxanthine aminophylline (10 and 30 mg/kg i.p.) antagonized the R-PIA- and NECA-induced elevation of prolactin suggesting an adenosine receptor-mediated effect. The dopaminergic agents L-dopa and bromocriptine antagonized the R-PIA and NECA-induced increase in serum prolactin. Haloperidol (a dopamine antagonist) and alpha-methyl-p-tyrosine (a catecholamine synthesis inhibitor) potentiated the R-PIA-induced effects. R-PIA and NECA did not displace 3H-haloperidol from rat striatal membranes nor effect in vitro prolactin release from rat anterior pituitary cells grown in culture. Based upon these findings it is postulated that R-PIA and NECA may be increasing prolactin secretion in part by inhibiting central dopamine release, although other mechanisms may also be operating.
D000241:Adenosine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide); D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D003342:Corpus Striatum / Q000378:metabolism; D006220:Haloperidol / Q000378:metabolism; D066298:In Vitro Techniques; D007980:Levodopa / Q000097:blood; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D010660:Phenylisopropyladenosine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism; D011983:Receptors, Purinergic; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D000628:Aminophylline; D010660:Phenylisopropyladenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D001971:Bromocriptine; D007980:Levodopa; D019805:alpha-Methyltyrosine; D011388:Prolactin; D006220:Haloperidol; D000241:Adenosine