The influence of agonists and antagonists of dopaminergic system on the formation of audiogenic seizures in rats during the ethanol abstinence period.

There have been numerous studies on the influence of ethanol on neurotransmitters, with conflicting results for the individual transmitters. It also refers to dopamine Hunt and Majchrowicz have found that dopamine circulation lowers after a prolonged administration of ethanol. The results of other experiments point out that such a long-lasting activity of ethanol has no influence on dopamine circulation. Tabakoff and Hoffman indicated that dopamine synthesis is lowered during the symptoms of ethanol abstinence. Griffiths et al. as well as Wajda et al. have proved that the level of dopamine in the striatum occurring at ethanol abstinence increases and comes back again to its initial value after 18 or 48 hrs. Fadda et al., while examining the prolonged influence of ethanol upon dopamine metabolism, has shown that after 24 hrs since the stop in ethanol administration, there has been an increase of dopamine level in the rat's frontal lobe of cortex cerebri. In other structures of the brain the dopamine level has not been changed. Darden and Hunt obtained the results showing a considerable decrease of dopamine liberation in the striatum during abstinence periods. In view of the biochemical research it is difficult to estimate explicitly the role of dopaminergic system in the appearance of dependence and symptoms of ethanol abstinence in the experimental animals. Some behavioral observations carried out on animals during the ethanol abstinence suggest that the prolonged administering of ethanol brings about hypofunction of central dopaminergic neurons.

The influence of bromocriptine on sexual activity in ethanol-exposed male rats.

Long-lasting intake of ethanol and its influence on certain changes in the activity of male sexual hormones is the subject of numerous experiments. It is suggested that the decreased libido, hypotrophy of testicles and impotence in individuals subjected to ethanol, are connected with the lowered level of testosterone. Various mechanisms may be responsible for such an activity of ethanol. There has been pointed out that long-lasting intake of ethanol quickens the metabolism of testosterone in the liver. The results of other experiments indicate that ethanol and/or its metabolite, acetaldehyde decrease the biosynthesis of testosterone in the Leydig cells. It has been proved, too, that ethanol reduces the number of testicular gonadotropin receptors what, additionally, decreases the synthesis of testosterone. Another reason for the disordered function of gonads in alcoholics may be the influence of ethanol on the central nervous system structures. Particularly, it refers to the neurones of hypothalamus because they can regulate excretion of the hormones of anterior pituitary gland. In this way, hypothalamus may affect not only the level of the hormones produced by gonades but also to release pituitary prolactin. The present state of research indicates that ethanol results in clear changes in the function of the dopaminergic system of the brain. The influence of ethanol upon the neurones of this system depends on its dose and the period of activity. Most researches point out that prolonged administration of ethanol leads to hypofunction of dopaminergic neurones of the brain.