The Journal of Neuroscience, September 1, 2000, 20(17):6640-6647
Role of the Lateral Preoptic Area in Sleep-Related Erectile
Mechanisms and Sleep Generation in the Rat
Markus H.
Schmidt1,
Jean-Louis
Valatx2,
Kazuya
Sakai2,
Patrice
Fort2, and
Michel
Jouvet2
1 Cleveland Clinic Foundation, Department of Neurology,
Cleveland, Ohio 44195, and 2 University of Claude Bernard,
Institut National de la Santé et de la Recherche Médicale
U480, Lyon, France
Penile erections are a characteristic phenomenon of paradoxical
sleep (PS), or rapid eye movement sleep. Although the neural mechanisms
of PS-related erections are unknown, the forebrain likely plays a
critical role (Schmidt et al., 1999). The preoptic area is implicated
in both sleep generation and copulatory mechanisms, suggesting it may
be a primary candidate in PS erectile control. Continuous recordings of
penile erections, body temperature, and sleep-wake states were
performed before and up to 3 weeks after ibotenic acid lesions of the
preoptic forebrain in three groups of rats. Neurotoxic lesions
involving the medial preoptic area (MPOA) and anterior hypothalamus
(n = 5) had no significant effects on either
erectile activity or sleep-wake architecture. In contrast, bilateral
lesions of the lateral preoptic region, with (n = 4) or without (n = 5) MPOA involvement, resulted in
a significant decrease in the number of erections per hour of PS,
number of PS-related erections, and PS phases exhibiting an erection.
Lesion analysis revealed that the candidate structures for PS erectile control include both the lateral preoptic area (LPOA) and ventral division of the bed nucleus of the stria terminalis; however, lesions
of the LPOA were the most effective in disrupting PS erectile activity.
LPOA lesioning also resulted in a long-lasting insomnia, characterized
by the significant increase in wakefulness and decrease in slow wave
sleep (SWS). PS architecture and waking-state erections remained
unchanged after lesion in all groups. These data identify an essential
role of the LPOA in both PS-related erectile mechanisms and SWS
generation. Moreover, higher erectile mechanisms appear to be
context-specific because LPOA lesioning selectively disrupted PS-related erections while leaving waking-state erections intact.
Key words:
sleep-related erections; nocturnal penile tumescence; medial preoptic area; lateral preoptic area; bed nucleus of the stria
terminalis; basal forebrain; insomnia; slow wave sleep; paradoxical
sleep; REM sleep
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