Effect of adenosine on gonadotropin and prolactin secretion by hemipituitaries in vitro

Incubation of hemipituitaries from male rats (200-220 g) with 10 nM to 1 micronM adenosine induced a dose-dependent decrease of the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) into the medium, and increased prolactin (PRL) secretion. The effects of 10 nM adenosine were blocked by 100 nM ceffeine, wereas 100 nM ceffeine alone had also inhibited 10 nM luteinizing hormone-releasing hormone (LHRH)-induced LH and FSH release by > 90%. These data indicate a regulatory role for adenosine in pituitary LH, FSH and PRL release, and also a possible modulatory effect of adenosine on the LHRH-LH and FSH system

Substance P injected into the medial preoptic area inhibits sodium, potassium and water urinary excretion: putative modulation of the cholinergic system

Substance P (SP, 1.5 nmol) injected into the medial preoptic area (MPOA) of conscious, unrestrained, water-loaded male rats induced a significant decrease in urinary sodium, potassium and water excretion. In contrast, a significant natriuretic effect was observed after injection of 0.3 nmol of a specific competitive SP antagonist ([D-Pr**2, D-Trp**7,**9]-substance P). SP partially blocked the carbachol-induced natriuresis in a time-dependent manner. These data indicate a tonic inhibitory action of SP on sodium excretion and suggest a putative modulatory action of SP on the cholinergic system