1.Calcium/calmodulin-dependent nitric oxide synthase activity in the CNS of Aplysia californica: biochemical characterization and link to cGMP pathways.
Bodnárová M1, Martásek P, Moroz LL. J Inorg Biochem. 2005 Apr;99(4):922-8.
We characterized enzymatic activity of nitric oxide synthase (NOS) in the central nervous system of Aplysia californica, a popular experimental model in cellular and system neuroscience, and provided biochemical evidence for NO-cGMP signaling in molluscs. Aplysia NOS (ApNOS) activity, determined as citrulline formation, revealed its calcium-/calmodulin-(Ca/CaM) and NADPH dependence and it was inhibited by 50% with 5mM of W7 hydrochloride (a potent Ca/CaM-dependent phosphodiesterase inhibitor). A representative set of inhibitors for mammalian NOS isoforms also suppressed NOS activity in Aplysia. Specifically, the ApNOS was inhibited by 65-92% with 500 microM of L-NAME (a competitive NOS inhibitor) whereas d-NAME at the same concentration had no effect. S-Ethylisothiourea hydrobromide (5mM), a selective inhibitor of all NOS isoforms, suppressed ApNOS by 85%, l-N6-(1-iminoethyl)lysine dihydrochloride (L-NIL, 5mM), an iNOS inhibitor, by 78% and L-thiocitrulline (5mM) (an inhibitor of nNOS and iNOS) by greater than 95%.
2.A study of the mechanisms involved in the neurotoxic action of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') on dopamine neurones in mouse brain.
Colado MI1, Camarero J, Mechan AO, Sanchez V, Esteban B, Elliott JM, Green AR. Br J Pharmacol. 2001 Dec;134(8):1711-23.
1. Administration of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') to mice produces acute hyperthermia and long-term degeneration of striatal dopamine nerve terminals. Attenuation of the hyperthermia decreases the neurodegeneration. We have investigated the mechanisms involved in producing the neurotoxic loss of striatal dopamine. 2. MDMA produced a dose-dependent loss in striatal dopamine concentration 7 days later with 3 doses of 25 mg kg(-1) (3 h apart) producing a 70% loss. 3. Pretreatment 30 min before each MDMA dose with either of the N-methyl-D-aspartate antagonists AR-R15896AR (20, 5, 5 mg kg(-1)) or MK-801 (0.5 mg kg(-1)x3) failed to provide neuroprotection. 4. Pretreatment with clomethiazole (50 mg kg(-1)x3) was similarly ineffective in protecting against MDMA-induced dopamine loss. 5. The free radical trapping compound PBN (150 mg kg(-1)x3) was neuroprotective, but it proved impossible to separate neuroprotection from a hypothermic effect on body temperature.
3.The neuronal NOS inhibitor L-MIN, but not 7-NINA, reduces neurotoxic effects of chronic intrastriatal administration of quinolinic acid.
Bazzett T1, Geiger A, Coppola B, Albin R. Brain Res. 1997 Nov 14;775(1-2):229-32.
Rat striata were exposed to 15 mM quinolinic acid (QUIN), or QUIN plus the nitric oxide synthase inhibitors S-methyl-L-thiocitrulline dihydrochloride (L-MIN) or 7-nitroindazole monosodium salt (7-NINA) for 21 days. Co-administration of 100 microM or 1 mM L-MIN with QUIN significantly reduced lesion volume compared to QUIN alone. Co-administration of 1 microM or 10 microM L-MIN with QUIN had no significant effect. There was no significant effect of 7-NINA co-administered with QUIN compared to QUIN alone. L-MIN reduction of lesion volume supports the contention that neuronal nitric oxide synthase is a mediator of excitotoxic injury.