Strychnine-induced seizures in mice: the role of noradrenaline.
1. The effects of some noradrenergic agents on seizures induced by strychnine were investigated in mice. 2. Strychnine (0.5-4 mg/kg, i.p.) dose-dependently produced tonic seizures. 3. DOPS (4-8 mg/kg, i.p.) significantly shortened the latency of seizures elicited by strychnine (2 mg/kg, i.p.). Similarly, DOPS (4 mg/kg, i.p.) effectively increased the incidence and significantly shortened the latency of seizures induced by strychnine (1 mg/kg, i.p.). 4. Imipramine (20-40 mg/kg, i.p.) and pargyline (200 mg/kg, i.p.) significantly shortened the latency of strychnine (2 mg/kg, i.p.)-induced seizures. 5. Phentolamine (5-20 mg/kg, i.p.) effectively antagonised the seizures elicited by strychnine (2 mg/kg, i.p.). Furthermore, phentolamine (10 mg/kg, i.p.) attenuated the seizure-potentiating effect of DOPS (4 mg/kg, i.p.). 6. Propranolol (0.5-2 mg/kg, i.p.) and prazosin (1-2 mg/kg, i.p.) reduced the incidence and significantly delayed the latency of seizures induced by strychnine (2 mg/kg, i.p.). 7. Reserpine (5-10 mg/kg, i.p.) significantly prolonged the latency of strychnine (2 mg/kg, i.p.)-induced seizures. 8. Clonidine (0.25-1 mg/kg, i.p.) dose-dependently and significantly antagonised strychnine (2 mg/kg, i.p.)-induced seizures. 9. Idazoxan (1-4 mg/kg, i.p.) in a dose related manner significantly shortened the latency of seizures induced by strychnine (2 mg/kg, i.p.). Similarly, idazoxan (2 mg/kg, i.p.) profoundly potentiated seizures elicited by strychnine (1 mg/kg, i.p.). Idazoxan (4 mg/kg, i.p.) significantly antagonised the protective effect of clonidine (1 mg/kg, i.p.) against strychnine (2 mg/kg, i.p.)-induced seizures. 10. Disulfiram (3 x 25 - 3 x 100 mg/kg, i.p.) significantly attenuated strychnine (2 mg/kg, i.p.)-induced seizures. DOPS (4 mg/kg, i.p.) significantly potentiated strychnine seizures in disulfiram (3 x 100 mg/kg, i.p.)-pretreated animals. 11. These results indicate that enhancement of noradrenergic neurotransmission potentiates strychnine seizures in mice.
Amabeoku
G
G
Department of Clinical Pharmacology, Medical School, University of Zimbabwe, Harare.
Chandomba
R
R
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004221:Disulfiram / Q000494:pharmacology; D015103:Droxidopa / Q000494:pharmacology; D019329:Idazoxan; D007099:Imipramine / Q000494:pharmacology; D008297:Male; D051379:Mice; D010293:Pargyline / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects*; D012110:Reserpine / Q000494:pharmacology; D012640:Seizures / Q000139:chemically induced* / Q000503:physiopathology*; D013331:Strychnine / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D011941:Receptors, Adrenergic; D012110:Reserpine; D010293:Pargyline; D011433:Propranolol; D013331:Strychnine; D015103:Droxidopa; D003000:Clonidine; D007099:Imipramine; D004221:Disulfiram; D011224:Prazosin; D019329:Idazoxan; D010646:Phentolamine