Neuronal activity in the female rat preoptic area associated with sexual motivation and consummation

Preoptic area (POA) neuronal activity promotes sleep, but the localization of critical sleep-active neurons is not completely known. Thermal stimulation of the POA also facilitates sleep. This study used the c-Fos protein immunostaining method to localize POA sleep-active neurons at control (22°C) and mildly elevated (31.5°C) ambient temperatures. At 22°C, after sleep, but not after waking, we found increased numbers of c-Fos immunoreactive neurons (IRNs) in both rostral and caudal parts of the median preoptic nucleus (MnPN) and in the ventrolateral preoptic area (VLPO). In animals sleeping at 31.5°C, significantly more Fos IRNs were found in the rostral MnPN compared with animals sleeping at 22°C. In VLPO, Fos IRN counts were no longer increased over waking levels after sleep at the elevated ambient temperature. Sleep-associated Fos IRNs were also found diffusely in the POA, but counts were lower than those made after waking. This study supports a hypothesis that the MnPN, as well as the VLPO, is part of the POA sleep-facilitating system and that the rostral MnPN may facilitate sleep, particularly at elevated ambient temperatures.

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2309 Changes in the neural activity of female rat preoptic area during sexual behavior

Neuroscience Research ◽

10.1016/s0168-0102(97)90738-0 ◽

1997 ◽

Vol 28 ◽

pp. S268

Author(s):

Akira Kato ◽

Yasuo Sakuma

Keyword(s):

Sexual Behavior ◽

Neural Activity ◽

Preoptic Area ◽

Female Rat

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Lipopolysaccharide effects on neuronal activity in rat basal forebrain and hypothalamus during sleep and waking

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.278.3.r620 ◽

2000 ◽

Vol 278 (3) ◽

pp. R620-R627

Author(s):

Xinzheng Xi ◽

Linda A. Toth

Keyword(s):

Neuronal Activity ◽

Basal Forebrain ◽

Preoptic Area ◽

Intraperitoneal Administration ◽

Brain Regions ◽

Neuronal Firing ◽

Firing Patterns ◽

Firing Rates ◽

Neuronal Mechanisms ◽

The Brain

Peripheral administration of lipopolysaccharide (LPS) is associated with alterations in sleep and the electroencephalogram. To evaluate potential neuronal mechanisms for the somnogenic effects of LPS administration, we used unanesthetized rats to survey the firing patterns of neurons in various regions of rat basal forebrain (BF) and hypothalamus during spontaneous sleep and waking and during the epochs of sleep and waking that occurred after the intraperitoneal administration of LPS. In the brain regions studied, LPS administration was associated with altered firing rates in 39% of the neurons examined. A larger proportion of LPS-responsive units showed vigilance-related alterations in firing rates compared with nonresponsive units. Approximately equal proportions of LPS-responsive neurons showed increased and decreased firing rates after LPS administration, with some units in the lateral preoptic area of the hypothalamus showing particularly robust increases. These findings are consistent with other studies showing vigilance-related changes in neuronal activity in various regions of BF and hypothalamus and further demonstrate that peripheral LPS administration alters neuronal firing rates in these structures during both sleep and waking.

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