Modulation of ethanol intake by serotonin uptake inhibitors.

The most commonly prescribed agents for decreasing ethanol intake are alcohol-sensitizing drugs; however, their efficacy is unproven, they are associated with toxicity, and there are several contraindications for use. A program to identify and test new drugs to decrease ethanol intake has focused on drugs that enhance central serotonergic neurotransmission and consistently attenuate ethanol consumption. Animal studies have shown consistent findings with direct and indirect serotonin (5-HT) agonists. Ethanol intake decreased after the administration of 5-HT precursors, 5-HT uptake inhibitors, intracerebral 5-HT, and postsynaptic 5-HT agonists; in contrast, destruction of serotonin-containing neurons with 5,6- or 5,7-dihydroxytryptamine increased ethanol intake. Administration of zimelidine (200 mg/day p.o.) to 16 healthy alcohol abusers was associated with a significant increase in number of abstinent days and a decrease in number of drinks consumed. Approximately 50% of the subjects were responders, 35% were partial responders, and 10%-15% were nonresponders. In a recent double-blind crossover study, citalopram, an even more selective serotonin uptake inhibitor, produced similar results. Because serotonin uptake inhibitors acted rapidly and subjects were not clinically depressed, this action is distinct from antidepressant effects. These drugs most likely interfere with the neurobiologic mechanisms regulating ethanol intake and provide an innovative approach for modulating the use of alcohol in problem drinkers.

Norepinephrine release in arteries of spontaneously hypertensive rats.

The role of the sympathetic nervous system in arterial hypertension cannot be properly evaluated until we know about its activity in the vessels themselves. In this study we investigated the effect of transmural stimulation on the tail artery - labelled in vitro with 3H-norepinephrine - of 7-9 week old spontaneously hypertensive rats (SHR) and Wistar Kyoto controls (WKR). Electrical stimulation using two frequencies (2 and 10 Hz) resulted in significantly more 3H overflow in vessels from SHR than from WKR. With 10 Hz stimulation the fractional release was also greater. Column chromatographic analysis of 3H overflow revealed that transmural stimulation in arteries of SHR enhanced mainly the release of norepinephrine and not of its metabolites. Significantly, an increased release of 3H-norepinephrine on stimulation was observed in SHR before the full development of hypertension suggesting that it might be a cause rather than a consequence of high blood pressure.