Ramalingam V, Fuller PM, Lu J, Saper CB (2008) Changes in energy metabolism after ventrolateral preoptic lesions in rats. Neuroscience 2008 Abstracts 586.14/SS47. Society for Neuroscience, Washington, DC.
Summary: The ventrolateral preoptic area (VLPO) is critically involved in the regulation of sleep. For example, lesions of the VLPO have been reported to cause profound insomnia and sleep fragmentation in rats. We evaluated possible changes in energy metabolism and motor behaviors secondary to chronic sleep restriction in VLPO lesioned rats. Under anesthesia (chloralhydrate, 350 mg/kg, i.p.), adult male Sprague Dawley rats (n = 17) received stereotaxic injections of orexin-saporin into the VLPO and were also implanted with EEG/EMG electrodes to assess sleep-wakefulness. Food, water, and body mass measurements were collected for 60 post-lesion days. Sleep-wakefulness was recorded on post-lesion Days 20 and 50. On post-lesion Day 60, the animals were deeply anesthetized and transcardially perfused with 10% formaldehyde. The brains were removed and processed for histological verification of the lesion site. VLPO lesions produced a decrease (34%) in non rapid eye movement sleep (NREM) and a decrease in NREM sleep bout duration (115 ± 5 sec in the VLPO lesioned rats Vs 133 ± 2 in control rats, P < 0.01). The VLPO lesioned animals also exhibited increased food intake when compared to the age-matched controls (0.45 ± 0.004 grams per gram of lean body mass Vs 0.39 ± 0.01 grams per gram of lean body mass, P = 0.05). Food intake (r = 0.90, P<0.001), but not water intake was positively correlated with the amount of sleep loss. Although the weight gain in the VLPO lesioned rats was not statistically different from the controls, it was negatively correlated with the amount of sleep loss in those animals (r = 0.51, P = 0.05). Although the VLPO lesioned animals balanced on the rotatrod for 25% less time than the controls, this did not reach statistical significance, perhaps because the variance was so high in both groups (87 ± 23 seconds Vs 116 ± 25 sec in control rats, P>0.05). The close correlation of sleep loss with changes in food intake and body weight after the VLPO lesions suggests that the increased feeding but lower body weight may be due to the sleep loss, rather than a consequence of damaging neurons adjacent to the VLPO, which would not correlate with sleep loss.
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