Choosing the Optimal Rat Stock as a Model for Research into Pharmacological Correction of Male Sexual Dysfunction.

The aim of the study is to identify the mechanisms mediating differences in sexual behavior between Sprague Dawley and Wistar rats, in order to choose the optimal stock for research into pharmacological correction of male sexual dysfunction. Materials and Methods: The experiments were carried out on sexually mature male rats of two stocks (Sprague Dawley and Wistar) weighing 350-450 g and aged 3 to 6 months. The comparative study of animal behavior was performed using standard tests for social interaction, locomotor activity, and anxiety level, as well as male mating behavior patterns. In order to determine the role of hypothalamic glycine receptors in the male sexual behavior, pharmacological manipulations of glycine receptor activity during mating with receptive females were conducted via bilateral intracerebral microcannulas implanted in the medial preoptic area (mPOA) of the male rat anterior hypothalamus. Results: The obtained results revealed statistically significant inter-stock differences in sexual behavior at the final consummatory stage of both intact animals and those after pharmacological activation of glycine receptors in the mPOA. The number of anxiety-related grooming patterns in the Open Field test significantly differed between the stocks for both intact animals and those after pharmacological activation of glycine receptors; the observed differences disappeared after the mPOA glycine receptors were blocked. In the Crowley test of social interaction, no significant difference was found between the stocks.Thus, the revealed difference in sexual behavior between Sprague Dawley and Wistar male rats is likely due to the difference in the level of anxiety, which, in turn, may be associated with difference in the mechanisms of glycinergic neurotransmission in the hypothalamic mPOAs of these rats. Conclusion: To study the relationship between the level of anxiety and sexual behavior, the choice of the Wistar rat stock is optimal since the male sexual behavior in this stock is more sensitive to stress than that in Sprague Dawley rats. However, to model male sexual dysfunction not associated with anxiety, the use of Sprague Dawley male rats should be preferred as these animals show more stable sexual behavior, which is less dependent on the level of anxiety.

Effects of Glycine Receptors of the Medial Preoptic Nucleus on Sexual Behavior of Male Wistar Rats.

We studied the effect of bilateral microinjections of selective pharmacological agents modulating glycine receptor activity into the medial preoptic nucleus on sexual behavior of male Wistar rats. Application of the glycine receptor blocker strychnine (20 µM, 2 µl) led to a significant inhibition of both appetitive and consummatory components of sexual behavior, whereas stimulation with glycine (1 mM and 50 µM, 2 µl) had no significant effect.