Methadone's effects on pentylenetetrazole-induced seizure threshold in mice: NMDA/opioid receptors and nitric oxide signaling.
Methadone is a synthetic opioid used to treat opiate withdrawal and addiction. Studies have demonstrated the impact of methadone on seizure susceptibility. This study investigated the modulatory impacts of acute and subchronic (three times daily for 5 days) intraperitoneal methadone treatment on pentylenetetrazole-induced clonic seizure threshold (CST) in mice, as well as the involvement of the nitric oxide, N-methyl-d-aspartate (NMDA), and µ-opioid pathways. Acute administration of different doses of methadone (0.1, 0.3, 1, and 3 mg/kg) 45 min before CST significantly decreased the seizure threshold. Additionally, pretreatment with noneffective doses of an opioid receptor antagonist (naltrexone) and NMDA receptor antagonists (ketamine and MK-801) inhibited methadone's proconvulsive activity in the acute phase, while l-NAME (a nonspecific nitric oxide synthase (NOS) inhibitor) did not affect that activity. In the subchronic phase, methadone (3 mg/kg) demonstrated an anticonvulsive effect. Although subchronic pretreatment with noneffective doses of l-NAME and 7-nitroindazole (a specific neuronal NOS inhibitor) reversed methadone's anticonvulsive activity, aminoguanidine (a specific inducible NOS inhibitor), naltrexone, MK-801, and ketamine did not change methadone's anticonvulsive characteristic. Our results suggest that NMDA and µ-opioid receptors may be involved in methadone's proconvulsive activity in the acute phase, while methadone's anticonvulsive activity may be modulated by neuronal NOS in the subchronic phase.
['Kazemi Roodsari|Soheil|S|', 'Bahramnejad|Erfan|E|', 'Rahimi|Nastaran|N|', 'Aghaei|Iraj|I|', 'Dehpour|Ahmad Reza|AR|']
D000818:Animals D000927:Anticonvulsants D016291:Dizocilpine Maleate D006146:Guanidines D007191:Indazoles D007649:Ketamine D008297:Male D008691:Methadone D051379:Mice D019331:NG-Nitroarginine Methyl Ester D009271:Naltrexone D009292:Narcotic Antagonists D009569:Nitric Oxide D019001:Nitric Oxide Synthase D010433:Pentylenetetrazole D016194:Receptors, N-Methyl-D-Aspartate D011957:Receptors, Opioid D012640:Seizures
methadone seizures mice nitric oxide N-methyl-d-aspartate