TY - JOUR TI - Effects of acute microinjections of thyroid hormone to the median preoptic nucleus of adult male rats on total sleep, loco-motor activity, and core body temperature DO - https://doi.org/doi:10.7282/T34Q7SMT PY - 2013 AB - One clinical effect of dysthyroidism is often the disruption of normal sleep. The hypothalamus, more specifically the Median Preoptic Nucleus (MePO) contains highly restricted neuroanatomical clusters of sleep-active neurons. These neurons express GABAA receptors, which have previously been implicated in the onset and maintenance of sleep. T3 has been shown to inhibit the actions of benzodiazepines in electrophysiological experiments. The current experiment served to investigate possible non-genomic action of T3 microinjections to the MePO on sleep behavior over a series of 48-hour intervals, comprised of one 24-hour control and one 24-hour experimental interval. Injections to the MePO, of varying doses of T3 caused significantly different response effects on REM, non-REM, core-body temperature, and locomotor activity. The date indicated that T3 at 1 µg and 3 µg T3 injections caused a significant decrease in Total Sleep (TS) (P<0.0001 and P< 0.0001 respectively). T3 yielded a significant decrease in non-REM sleep (NREMS) for the doses of 1 µg, and 3 µg injections of T3 (P <0.0001 and P<0.0001 respectively along with an increase in REM sleep (REMS) in doses of 1 µg, and 3 µg T3 injections (P<0.03 and P<0.0001 respectively) within 24 hours of injection. These effects may be due to possible neurotransmitter or neurosteroid-like properties of T3 in the brain, or they may be from inhibitory protein phosphorylation effects found in previous experiments. Since the effects of T3 were demonstrated after acute injections, the data is consistent with possible non-genomic actions of thyroid hormones in the adult brain. KW - Biology KW - Thyroid gland--Diseases KW - Sleep disorders KW - Thyroid hormones LA - eng ER -