Abstract
The cholinergic neurons in the brainstem (laterodorsal tegmental nucleus: LDT) have a role in the regulation of REM sleep. M. Schmidt have suggested that the cholinergic input to the preoptic area is crucial for induction of penile erection during REM sleep. In the present study, we examined the possible involvement of the cholinergic LDT neurons in the regulation of penile erection during REM sleep. Unanesthetized, head-restrained rats were used. Single neuronal activity was recorded through a glass pipette electrode. Penile erection is composed of two components; slow increase of the corpus spongiosum penis (CSP) pressure and sharp peaks riding on the slow increase. Several types of the LDT neurons showed firing patterns in close relation with penile erection including 1) the cholinergic neurons which showed tonic firing increase 20-30 sec before the erection. The firing increase of this type of neurons was well correlated with the slow increase of CSP pressure. 2) the cholinergic neurons which showed phasic firing in synchronous with the sharp CSP peaks. 3) the non-cholinergic neurons which decreased or stopped firing during erection. These results suggest that the cholinergic neurons in the LDT are involved in induction and excursion of penile erection during REM sleep, while the non-cholinergic neurons have inhibitory influences on penile erection. [J Physiol Sci. 2006;56 Suppl:S95]
