Role of the Lateral Preoptic Area in Sleep-Related Erectile Mechanisms and Sleep Generation in the Rat

Abstract

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 ϭ 5) had no significant effects on either erectile activity or sleep-wake architecture. In contrast, bilateral lesions of the lateral preoptic region, with (n ϭ 4) or without (n ϭ 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 sleepParadoxical sleep (PS), also known as rapid eye movement sleep, is characterized by several tonic and phasic phenomena, including cortical desynchronization, rapid eye movements, general muscle atonia, and penile erections. Whereas the neural control of PSrelated erections remains unknown, the executive mechanisms generating PS and its other tonic and phasic events are relatively well elucidated and localized within the mesopontine tegmentum and rostral medulla (Sakai 1985;Jones 1991).Using a new technique of chronic penile erection recording in the rat (Schmidt et al., 1995), we recently demonstrated that mesencephalic transections disrupt PS erectile activity even though PS remains otherwise qualitatively intact (Schmidt et al., 1999). These data suggest that forebrain structures rostral to the transection are necessary for the production of PS-related erections. The source of this forebrain control currently is a matter of speculation.Numerous forebrain structures have been implicated in rep...

Impaired GABA and Glycine Transmission Triggers Cardinal Features of Rapid Eye Movement Sleep Behavior Disorder in Mice

“…Lesion-induced loss of brainstem and hypothalamic GABA neurons destabilizes sleep and disrupts normal NREM-REM architecture (Lu et al, 2000;Schmidt et al, 2000). Our current findings indicate that glycine and GABA transmission are also important for normal sleep regulation.…”

Nocturnal penile tumescence and rigidity (NPTR) findings in spinal cord injured men with erectile dysfunction

“…31 Our SCI patients with incomplete cord lesions, that is, partially intact connections to forebrain centres, were the only ones with nearly normal erection duration during REM sleep, corroborating Schmidt's suggestions of a proerectile role of the lateral preoptic area. 32 However, waking-state erections remained unchanged after neurotoxic lesions of this forebrain area. 32 These data show that higher erectile mechanisms appear to be context-specific, as we concluded from our clinical observation, that quality of nocturnal erections does not always reflect waking erectile function.…”

“…32 However, waking-state erections remained unchanged after neurotoxic lesions of this forebrain area. 32 These data show that higher erectile mechanisms appear to be context-specific, as we concluded from our clinical observation, that quality of nocturnal erections does not always reflect waking erectile function. Whereas abnormal NPTRs imply-almost without exception-waking ED (except sleep disturbances), a normal NPTR result in patients with neurological disorders only suggests intact erectile mechanism during sleep, not warranting waking erections, which could be used for sexual intercourse.…”

“…It seems that nocturnal erections and waking PE/RE are generated by different neuronal mechanisms. To our knowledge, there is only one experimental approach in a rat model dealing with the neurophysiology of REM sleep-related erections by Schmidt et al [30][31][32] The authors elucidated by neural transections the effects of paraplegia on REM sleep-related erections and determined the brain level at which the mechanisms underlying erectile activity are generated. It has to be mentioned that Schmidt's group investigated primarily the influence of high spinal cord and forebrain transections to erection function in rats, 30 whereas we targeted the effects of different spinal lesion levels and completeness to human erectile function.…”

The false organic–psychogenic distinction and related problems in the classification of erectile dysfunction

“…Specifically, lesions in the lateral preoptic area of Organic-psychogenic ED distinction BD Sachs the hypothalamus of rats drastically curtail erection during REM sleep without affecting REM sleep per se, and without affecting erection in any other context. 35 This example is just one of many showing that the neural and endocrine mediation of erection differs from one sexual context to another, depending on whether the sexual stimulation is genital touch, copulation, a response to remote stimulation such as smell or sight, or sleep related. 11 Therefore, disorders in the organic basis of erection in one context may or may not be predictive of ED in another context.…”