Acute effects of toluene on circadian rhythms of sleep-wakefulness and brain monoamine metabolism in rats.
Acute effects of a single i.p. injection of toluene on circadian rhythms of sleep-wakefulness were investigated in rats which were chronically implanted with EEG and EMG electrodes for polygraphic recordings. The toluene injection produced an initial increase in wakefulness (W) and a subsequent increase in slow-wave sleep (SWS) during the dark period. In an attempt to clarify mechanisms of these biphasic effects of toluene on sleep-wakefulness rhythms, brain monoamines and their metabolites were determined at the times of the initial increase in W and the increased SWS. The initial increase in W was associated with an increase in cortical NA, MHPG and 5-HT together with a decrease in cortical 5-hydroxyindoleacetic acid (5-HIAA), while the increased SWS during the dark period was associated with an increase in 5-HIAA and a concomitant decrease in 3-methoxy-4-hydroxyphenylglycol (MHPG). The toluene-induced changes in sleep-wakefulness seemed to be manifested at lower blood levels of toluene than the behavioral signs of central nervous system (CNS) depression. These biphasic effects of toluene on circadian sleep-wakefulness rhythms are discussed in terms of the reciprocal interactions between central 5-HT and NA neurons.
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002395:Catecholamines / Q000032:analysis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm / Q000187:drug effects*; D006719:Homovanillic Acid / Q000032:analysis; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D007274:Injections, Intraperitoneal; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis; D012890:Sleep / Q000187:drug effects*; D014050:Toluene / Q000494:pharmacology*
D002395:Catecholamines; D012701:Serotonin; D014050:Toluene; D008734:Methoxyhydroxyphenylglycol; D006897:Hydroxyindoleacetic Acid; D006719:Homovanillic Acid