Neurotoxic effects induced by intracerebral and systemic injection of paraquat in rats.
1 The neurotoxic effects elicited by paraquat after systemic and intracerebral injection were studied in rats. 2 Intrahippocampal microinfusion of paraquat (0.1 mumol) produced behavioural stimulation and electrocortical (ECoG) excitation followed, at 24 h, by multifocal brain damage. Similarly, microinfusion of paraquat (0.2-0.4 mumol) into the locus coeruleus, substantia nigra or into the raphe nuclei, where noradrenergic, dopaminergic and serotonergic neurons are present, respectively, elicited potent excitotoxic effects (n = 6 rats per dose and area). A lower dose (0.01 mumol) of the herbicide or injection of the vehicle (1.0 microliter) did not produce any behavioural, ECoG or neurodegenerative effect. 3 After systemic administration, paraquat (20 mg kg-1 s.c.) evoked limbic motor seizures and ECoG epileptogenic discharges; in 10 out of 15 treated rats neuronal cell death was observed in the pyriform cortex, but not in other brain regions. A dose of 5 mg kg-1 was ineffective. 4 Among the regions of the brain studied, high concentrations of paraquat were detected in the pyriform cortex 24 h after systemic administration (5.0 and 20 mg kg-1 s.c.) lower levels being observed in the caudate nucleus. 5 In conclusion, paraquat, given systemically or intracerebrally in rats produces neurodegenerative effects.
Department of Biology, University of Rome Tor Vergata, Italy.
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D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000473:pathology; D007276:Injections, Intraventricular; D007279:Injections, Subcutaneous; D008297:Male; D010269:Paraquat / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000139:chemically induced*
D010269:Paraquat