EVIDENCE FOR INVOLVEMENT OF THE SUBCOERULEUS NUCLEUS AND NUCLEUS RAPHE MAGNUS IN URINE STORAGE AND PENILE ERECTION IN DECEREBRATE RATS

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Abstract
Micturition and male sexual activity require the lower urinary tract to function. During the sexual act, micturition must be inhibited and urine stored in the bladder. We studied the role of the brainstem in relation to both micturition/urine storage and penile erection in rats. Wire electrodes were placed on the dorsal nerve of the penis and microelectrodes for stimulation were introduced into the brainstem in decerebrate male rats. Electrical stimulation was used to locate optimally responding sites by monitoring the isovolumetric intravesical pressure and intracavernous pressure. Electrical stimulation of the dorsal nerve of the penis, the subcoeruleus nucleus in the rostral pons, and the nucleus raphe magnus in the caudal pons increased intracavernous pressure, but inhibited rhythmic bladder contractions. Electrical stimulation of Barrington's nucleus (the pontine micturition center in the rat) in the rostral pons induced bladder contraction. Stimulation of the pontine reticular formation did not increase intracavernous pressure. Acute transection of the thoracic spinal cord eliminated rhythmic bladder contractions, but gave rise to sporadic increments of intracavernous pressure. This electrophysiological study demonstrated that the subcoeruleus nucleus and nucleus raphe magnus are involved in both urine storage and penile erection, and that their physiological functions are reciprocally controlled; so that erection leads to inhibition of micturition.