We studied the effect of baclofen (GABA(B) receptor agonist) on the behavior of male mice with different levels of anxiety in tests for social and sexual contact and on blood testosterone levels. The drug reduced testosterone level and behavioral reaction to an unknown male in intact animals and did not modulate the hormone level and social contacts in anxious mice. In the test with receptive female, baclofen reduced testosterone level and sexual motivation in intact males and did not modulate the hormone level and initial sexual interest in anxious mice. Parallelism in the development of behavioral and endocrine components of the reaction to social and sexual stimuli confirms possible involvement of testosterone in psychotropic effects of baclofen.

The psychotropic effects of the GABA(B) receptor agonist baclofen (1, 2.5, and 5 mg/kg, i.p.) on anxiety, sexual motivation, and olfactory perception were studied in male mice in different psychoemotional states. Baclofen decreased the rate of perception (analysis) of olfactory stimuli. The effects of baclofen on behavior depended on the psychoemotional state of the animals. In intact males, baclofen administration had an anxiolytic effect in the elevated plus-maze (EPM) and social contacts tests and increased responses to males. In aggressive males, baclofen administration had anxiolytic effects in the EPM and restored levels of sexual motivation to the control level. In submissive males, baclofen administration had weak influences on anxiety levels in both tests, but prevented waning of sexual interest. The presence and absence of parallels in the development of anxiety and sexual reactions in animals in different social states are discussed.

The relevance of the social contact test "Wall" for evaluation of sexual motivation of male mice was tested and confirmed. Motivation of C57BL/6J male mice with alternative social experience (winners and victims in 10 and 20 daily male-male confrontations) was evaluated. Elevated primary sexual interest was detected in aggressive animals after 10 confrontations, while in submissive animals this interest was decreased; however after 20 confrontations sexual motivation in both groups was characterized by rapid exhaustion and low basal level of testosterone. Hence, the sexual function of male mice is inhibited under conditions of long social conflicts irrespective of previous experience of victories or defeats in male-male confrontations.

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We studied the effects of drugs modulating GABA content in the brain on communicative activity and sexual motivation of male mice. The effects of the drug depended on animal genotype and initial psychoemotional status. Aminooxyacetic acid elevating GABA content did not modulate communicative activity of intact males, reduced it in aggressive animals, restored in anxious animals, and promoted exhaustion of sexual motivation in anxious animals. Thiosemicarbazide reducing GABA level produced an anxiogenic effect and destabilized sexual motivation in intact males.