title: Nitric oxide signaling pathway in the anti-convulsant effect of adenosine against pentylenetetrazol-induced seizure threshold in mice.
abstract: The present study was performed to examine the involvement of nitric oxide (NO) signaling pathway in the anti-convulsant effect of adenosine against pentylenetetrazol seizure threshold in mice. Minimal dose of pentylenetetrazol (i.v., mg/kg) needed to induce different phases (myoclonic jerks, generalized clonus and tonic extension) of convulsions was recorded as an index of seizure threshold. Adenosine (100 or 200 mg/kg i.p.) produced a significant increase in the seizure threshold for convulsions induced by pentylenetetrazol i.v. infusion. The anti-convulsant effect of adenosine (100 mg/kg i.p.) was prevented by either L-arginine (50 mg/kg i.p.) [substrate for nitric oxide synthase (NOS)] or sodium nitroprusside (3 mg/kg i.p.) [a NO donor]. On the other hand, N(G)-nitro-L-arginine methyl ester (L-NAME, 2.5 mg/kg i.p.) [a non-selective NOS inhibitor] or 7-nitroindazole (7-NI) (25 mg/kg i.p.) [a specific neuronal nitric oxide synthase (nNOS) inhibitor] potentiated the anti-convulsant action of sub-effective dose of adenosine (50 mg/kg i.p.). Aminoguanidine (100 mg/kg i.p.) [a specific inducible NOS (iNOS) inhibitor] pre-treatment was not effective in inducing anti-convulsant effect with sub-effective dose of adenosine (50 mg/kg i.p.). Furthermore, the increase in seizure threshold elicited by adenosine (100 mg/kg i.p.) was also inhibited by concomitant administration with sildenafil (5 mg/kg i.p.) [phosphodiesterase 5 inhibitor]. In contrast, treatment of mice with methylene blue (1 mg/kg i.p.) [a direct inhibitor of both nitric oxide synthase (NOS) and soluble guanylate cyclase (sGC)] failed to induce anti-convulsant action with adenosine (50 mg/kg i.p.) against pentylenetetrazol i.v. infusion. The results demonstrated that the anti-convulsant action of adenosine in the pentylenetetrazol i.v. seizure threshold paradigm may possibly involve an interaction with the L-arginine-NO-cGMP pathway which may be secondary to the activation of adenosine receptors.
authors.affiliation: Pharmacology Division, University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh-160014, India.
authors.forename: Kiran Kumar
authors.initials: KK
authors.lastname: Akula
authors.forename: Ashish
authors.initials: A
authors.lastname: Dhir
authors.forename: S K
authors.initials: SK
authors.lastname: Kulkarni
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D001120:Arginine / Q000494:pharmacology; D003292:Convulsants; D000242:Cyclic AMP / Q000502:physiology; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D010433:Pentylenetetrazole; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D012640:Seizures / Q000139:chemically induced / Q000517:prevention & control*; D015398:Signal Transduction / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology
chemical_list: D000927:Anticonvulsants; D003292:Convulsants; D004791:Enzyme Inhibitors; D006146:Guanidines; D007191:Indazoles; D020030:Nitric Oxide Donors; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D000068677:Sildenafil Citrate; D000242:Cyclic AMP; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D000241:Adenosine; C004479:pimagedine; D008751:Methylene Blue; C080122:7-nitroindazole; D019331:NG-Nitroarginine Methyl Ester; D010433:Pentylenetetrazole