Experientia 38 (1982), Birkh~iuser Verlag, CH-4010 Basel/Switzerland excluded, extrapolating from experiments on animals, that an alteration of the dopaminergic and enkephalinergic systems may be involved in this disorder, though the complexity of the numerous psychological factors involved should always be borne in mind. The precise way in which Nx enhances the sexual stimulant effect of NPA is as yet undetermined. We interpreted our findings as indicating that some Nx-actions are related to the dopaminergic mechanism, which would confirm the existence of a relationship between the action of opiates and dopaminecontaining synapses in the brain 12'14-16. One possible explanation of the influence of Nx on the NPA-effect would involve a Nx blockade of the opiate receptors that have an inhibitory effect upon the dopaminergic system involved in the control of sexual behavior. On the other hand, the failure of Nx-pretreatment to potentiate the effect of a relatively high dose of NPA (8 gg 9 kg -1) on mating behavior in sexually active rats may be because this NPA dose was already maximally active in these experiments. The findings in the present study on impotent rats would appear to contradict the observation by Gessa 2 that Nx induced a complete copulatory pattern in sexually inactive male rats. This discrepancy may well result from the different experimental conditions, however. In impotent rats, NPA (8 gg. kg -1) was able to induce copulatory behavior in about 50% of the animals, confirming our previous results ~~ Nx-pretreatment did not alter the percentage of rats displaying the copulatory pattern, nor did it influence IF and EL, which were very low after NPAtreatment compared with the values for saline-treated sexually active rats. In conclusion, the ability of Nx to potentiate the NPA-effect on copulatory behavior can be ob-953 served only in a normally functioning physiological system, that is, in sexually active rats. In a situation of complete sexual inadequancy, that is in impotent males, while a strong dopaminergic agonist is still capable of activating sexual behavior in about 50% of rats, no stimulant effect of Nx can be shown.
76, 3006 (1979).
Mineralocorticoid treatment and the adrenalectomy-induced increase in monoamine oxidase activity !
J.W. Dailey, H.D. Battarbee and L. McNatt
Department of Pharmacology and Therapeutics, and Department of Physiology and Biophysics, LSU Medical Center, P.O. Box 33932, Shreveport (Louisiana 71130, USA), 28 July 1981Summary. Bilateral adrenalectomy in the rat results in an increase in heart monoamine oxidase activity in animals drinking water and in animals drinking 0.9% saline. Daily administration of deoxycorticosterone acetate prevented the increased monoamine oxidase activity in the animals drinking saline but not in those drinking water.As early as 1936, Richter 2 reported that normal rats drank similar amounts of sodium chloride solution and water when given a choice. In contrast, adrenalectomized animals were found to drink more of the saline solution. In ano...
