Sensory and motor aspects of the coital reflex in the spinal male rat.

In the present study the sensory and motor aspects of the coital reflex model in male rats were evaluated. Electromyographic reflex activity after mechanical stimulation of the urethra, penis and scrotal skin was recorded in all genital muscles. The possibility that a facilitatory mechanism of these muscular responses was located in the rat spinal cord was evaluated by removing the genital afferents. Results showed that urethral, penile and scrotal stimulation evoked the coital reflex in all genital muscles. Similarly, coital responses were obtained spontaneously in deafferentated animals. The parameters among the motor patterns evoked with the different mechanical stimuli were very similar. Parameters of spontaneous motor patterns were not importantly different from those obtained reflexively. A conspicuous difference between these responses was the presence of an after-discharge activity in genitally-stimulated animals. Additionally, it was found that this motor pattern can be exhausted with repeated stimulation. Spontaneous responses did not show the exhaustion phenomenon. Results are discussed in the context of the sensory-motor aspects of male sexual behaviour.