Pentylenetetrazol: effect on carbaryl-induced changes of serotonin metabolism in pons-medulla of rat brain.
Oral administration of carbaryl to adult male albino rats produced a dose dependent increase in the steady state level of 5-hydroxytryptamine (5-HT) at 1.00 h in pons-medulla (PM). 5-Hydroxyindole acetic acid (5-HIAA) concentration was significantly elevated only in response to a higher dose of this pesticide under similar conditions. A time course study with carbaryl and pentylenetetrazol (PTZ) showed a characteristic elevation of the steady state level of 5-HT in PM, but the 5-HIAA level was significantly elevated at 0.5 h only after carbaryl treatment. No significant change of the 5-HIAA level was evident after administration of PTZ alone or in combination with carbaryl. Tryptophan concentration was significantly elevated in PM at 0.5 h after carbaryl treatment and at 1.0 h after carbaryl + PTZ treatment. No significant change of tryptophan concentration was evident after the administration of PTZ alone under similar conditions. Measurement of (1) pargyline induced (a) accumulation of 5-HT and (b) depletion of 5-HIAA levels, and (2) probenecid-induced accumulation of 5-HIAA level in presence and absence of carbaryl and revealed that carbaryl accelerated the synthesis as well as the breakdown of 5-HT, whereas PTZ alone or in combination with carbaryl accelerated the synthesis of 5-HT without affecting its catabolism. The potency of this pesticide in elevating the pargyline-induced accumulation of 5-HT is in the order of carbaryl + PTZ greater than PTZ congruent to carbaryl. These results suggest that the carbaryl-induced increase in the synthesis of 5-HT is potentiated, and the turnover is reduced, in PM when PTZ is administered to the carbaryl-intoxicated rats.
D000818:Animals; D012721:Carbaryl / Q000494:pharmacology*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008526:Medulla Oblongata / Q000187:drug effects* / Q000378:metabolism; D010293:Pargyline / Q000494:pharmacology; D010433:Pentylenetetrazole / Q000494:pharmacology*; D011149:Pons / Q000187:drug effects* / Q000378:metabolism; D011339:Probenecid / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D010293:Pargyline; D011339:Probenecid; D012721:Carbaryl; D010433:Pentylenetetrazole