Testosterone treatment induces behavioral disinhibition in adult male rats

The importance of testosterone for impulsive-like behavior is unclear. Here we studied the effect of testosterone administration during 6 and 14 days (separate experiments) with one, three and five testosterone-filled silastic capsules implanted subcutaneously on shock-induced behavioral inhibition and on flunitrazepam-induced disinhibition in a modified Vogel's drinking conflict model in rats. Alleviation of shock-induced behavioral inhibition has been suggested to reflect impulsive-like behavior and/or anxiolysis. Treatment with the highest testosterone dose used for 6 (Experiment 1) and 14 (Experiment 3) days increased the number of shocks accepted. Testosterone treatment affected serum levels of testosterone and accessory sex organ weights. Flunitrazepam induced behavioral disinhibition in both testosterone-treated (for 14 days) and sham-treated rats. Moreover, testosterone treatment for 14 days resulted in enhanced GABA-induced 36Cl- uptake into synaptoneurosomes as compared to controls. In conclusion, testosterone produces behavioral disinhibition and may enhance brain GABAA receptor function.