Diurnal rhythm in the plasma level of total and free tryptophan and cortisol in rabbits. Effect of haloperidol and chlorpromazine.
Plasma tryptophan level varied diurnally with highest concentrations at 12 noon (P less than 0.001); at that time free tryptophan level was lowest. The mean 8 h and 16 h cortisol levels were 70% higher compared to levels obtained at 24 h. Chronic administration of haloperidol and chlorpromazine led to significant increase in the plasma tryptophan (P less than 0.001 and P less than 0.1, respectively) compared to saline-treated rabbits. This change was associated with corresponding constant or reduced free tryptophan levels, and a diminution in plasma cortisol level (10 microgram/l) compared with controls (34 microgram/l). The results suggest that tryptophan in plasma is poorly transported in the brains of rabbits treated with chlorpromazine, and that treatment with haloperidol or chlorpromazine may lead to a reduced tryptophan flux into the kynurenine pathway.
D000818:Animals; D002746:Chlorpromazine / Q000494:pharmacology*; D002940:Circadian Rhythm; D005260:Female; D006220:Haloperidol / Q000494:pharmacology*; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D011817:Rabbits; D014364:Tryptophan / Q000097:blood*
D014364:Tryptophan; D006220:Haloperidol; D002746:Chlorpromazine; D006854:Hydrocortisone