Modulating effects of biogenic amines on calcium and ethanol-induced sleeping time.

The present study was carried out in order to clarify the mechanism of calcium prolongation of ethanol-induced sleep. p-Chlorophenylalanine (PCPA, 300 mg/kg), alpha-methyltyrosine (alpha MPT, 100 mg/kg) and diethyldithiocarbamate (DDC, 250 mg/kg) were administered intraperitoneally (IP) to mice to reduce the levels of serotonin (5-HT), dopamine (DA) and norepinephrine (NE) respectively in the brain. Sleeping time was then measured following the administration of ethanol (4.5 g/kg, IP) both with and without CaCl2 (20 mumol/kg, intravenous (IV)). When saline (IP) plus CaCl2 (IV) was administered, the duration of ethanol-induced sleep was prolonged by 100% as compared with saline (IP) plus saline (IV). Duration of ethanol-induced sleep was not changed by PCPA, alpha MPT and DDC. On the other hand, the prolongation of ethanol-induced sleep by CaCl2 was antagonized by PCPA, alpha MPT and DDC. Also, only the DA level in the cerebrum was increased by 25% by administration of CaCl2. We suggest that the increase in ethanol-induced sleeping time due to CaCl2 results from the increase in biogenic amines in the brain.