Antisense mRNA for NPY-Y-1 receptor in the medial preoptic area increases prolactin secretion

We investigated the participation of neuropeptide Y-Y-1 receptors within th e medial preoptic area in luteinizing hormone, follicle-stimulating hormone and prolactin release. Four bilateral microinjections of sense (control) o r antisense 18-base oligonucleotides of messenger ribonucleic acid (mRNA) ( 250 ng) corresponding to the NH2-terminus of the neuropeptide Y-1 receptor were performed at 12-h intervals for two days into the medial preoptic area of ovariectomized Wistar rats (N = 16), weighing 180 to 200 g, treated wit h estrogen (50 mu g) and progesterone (25 mg) two days before the experimen ts between 8.00 and 10:00 a.m. Blockade of Y-1 receptor synthesis in the me dial preoptic area by the antisense mRNA did not change plasma luteinizing hormone or follicle-stimulating hormone but did increase prolactin from 19. 6 +/- 5.9 ng/ml in the sense group to 52.9 +/- 9.6 ng/ml in the antisense g roup. The plasma hormones were measured by radioimmunoassay and the values are reported as mean +/- SEM. These data suggest that endogenous neuropepti de Y in the medial preoptic area has an inhibitory action on prolactin secr etion through Y-1 receptors.