Age-related effects of chlorpyrifos and parathion on acetylcholine synthesis in rat striatum.
We compared the in vivo effects of two organophosphorus (OP) insecticides, chlorpyrifos (CPF) and parathion (PS) on acetylcholine (ACh) synthesis in neonatal, juvenile and adult rats. Basal levels of ACh synthesis were highest in adult rats, intermediate in juveniles and lowest in neonates. Following high (maximum tolerated dosage) subcutaneous exposure to either insecticide, relatively similar degrees of cholinesterase inhibition were noted, but the time to peak reduction varied among the age groups. CPF had no effect on ACh synthesis in neonates, increased synthesis in juveniles and decreased synthesis in adults, but only in the low dose group. PS had more consistent effects on ACh synthesis, decreasing transmitter synthesis in neonates (24 h after dosing) but increasing synthesis in juveniles and adults at both 4 and 24 h after exposure. Selective changes in neurotransmitter synthesis may contribute to differential age-related toxicity of these agents.
Karanth
Subramanya
S
Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 264 McElroy Hall, Stillwater, OK 74078, USA. karanth@okstate.edu
Pope
Carey
C
D000109:Acetylcholine / Q000378:metabolism*; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D004390:Chlorpyrifos / Q000633:toxicity*; D002802:Cholinesterases / Q000378:metabolism; D003342:Corpus Striatum / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D005260:Female; D007306:Insecticides / Q000633:toxicity; D007928:Lethal Dose 50; D008297:Male; D010278:Parathion / Q000633:toxicity*; D011874:Radiometry / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D007306:Insecticides; D010278:Parathion; D002802:Cholinesterases; D004390:Chlorpyrifos; D000109:Acetylcholine