strychnine and 3-nitropropionic-acid

3-Nitropropionic acid (3-NPA) is a naturally occurring fungal toxin that leads to ATP-depletion by inhibiting mitochondrial succinate dehydrogenase and produces chemical anoxia. The present study was conducted to identify the involvement of inhibitory system in 3-NPA-induced depression of spinal reflexes.. The monosynaptic (MSR) and polysynaptic reflex (PSR) potentials were recorded at ventral root by stimulating the corresponding dorsal root in hemisected (sagitally) spinal cord from 4-8 day old rats. Effect of 3-NPA in the absence and presence of antagonists was evaluated on the reflexes.. Superfusion of 3-NPA (3.4 mM) depressed the reflexes in a time-dependent manner abolishing them by 35 min. The T-50 values were around 18 and 16 min for MSR and PSR, respectively. An NMDA receptor antagonist, DL-2-amino-5-phosphonovaleric acid (10 microM) failed to block the 3-NPA (3.4 mM)-induced depression of reflexes. Superfusion of bicuculline (GABAA receptor antagonist; 1 microM), or strychnine (glycineA receptor antagonist; 1 microM) antagonized the 3-NPA-induced depression of reflexes significantly. The T-50 values were 26 and 30 min in bicuculline and strychnine pretreated groups, respectively and were significantly greater than 3-NPA only group.. The results indicate that 3-NPA-induced depression of spinal reflexes is partially mediated by GABAergic and glycinergic inhibitory transmission.

Topics: 2-Amino-5-phosphonovalerate; Animals; Animals, Newborn; Bicuculline; Evoked Potentials; Excitatory Amino Acid Antagonists; GABA Antagonists; gamma-Aminobutyric Acid; Glycine; Glycine Agents; Neurotoxins; Nitro Compounds; Propionates; Rats; Reflex; Spinal Cord; Strychnine; Synaptic Transmission