Effects of nociceptin on the spread and seizure activity in the rat amygdala kindling model: their correlations with 3H-leucyl-nociceptin binding.
The effects with pretreatment with nociceptin (0.03-30nmol, i.c.v.) were evaluated on the threshold for eliciting afterdischarge (ADT), generation and spread of seizure activity and postictal depression in rats with kindling stimulation. Nociceptin produced a decrease in ADT (32-45%) in rats with partial seizures (PS, stage II-III), and an increase (61-92%) in rats with generalized seizures (GS, kindled state). Nociceptin did not modify the behavioral changes, spike frequency and duration of afterdischarge elicited at ADT in both experimental groups. In rats with GS, nociceptin enhanced postictal depression (34-44%) evaluated with a recycling paradigm. Autoradiography experiments revealed enhanced nociceptin opioid receptor (NOP) binding in medial amygdala (22-26%), frontal (21-23%) and entorhinal (27-32%) cortices, and reduced binding in the substantia nigra pars compacta (28%) and medial central gray (29%) of rats with PS. The GS group displayed significant decreased NOP binding (40-70%) in most of the brain areas evaluated. These results suggest that nociceptin facilitates ictal activity in rats with PS, whereas in animals with GS, it induces inhibitory effects on ADT and enhances the postictal period. These effects correlate with significant changes in NOP binding.
Carmona-Aparicio
Liliana
L
Department of Pharmacobiology, Center of Research and Advanced Studies, Mexico City, Mexico.
Peña
Fernando
F
Borsodi
Anna
A
Rocha
Luisa
L
D000679:Amygdala / Q000187:drug effects* / Q000503:physiopathology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004828:Epilepsies, Partial / Q000503:physiopathology; D004829:Epilepsy, Generalized / Q000503:physiopathology; D007276:Injections, Intraventricular; D007696:Kindling, Neurologic / Q000187:drug effects*; D008297:Male; D018847:Opioid Peptides / Q000378:metabolism* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000503:physiopathology*; D000097629:Nociceptin
D018847:Opioid Peptides; D000097629:Nociceptin