involvement of the nucleus accumbensshell presynaptic nmda receptors on anxiolytic-like behaviors induced by nmda in adult male wistar rat

glutamatergic system stimulationthe nucleus accumbens shell, may affect anxiety-related behaviors, aversive learning and memory. glutamate receptors are differentially distributed in pre- and postsynaptic sites contributing to neuronal communications.the present study aimed to examine the possible involvement of the nac shell presynaptic nmda receptors on nmda induced responses, using the elevated-plus maze (epm) task in malewistar rats. bilateral guide cannulae were implanted to allow microinjection of glutamatergic agonist (nmda) or ca +2 channel blocker (skf96365 hydrochloride) agents. pretest intra-nac shell infusion of nmda induced anxiolytic-like behaviors and impaired the epm-associated memory upon test and retest, respectively. in addition our findings showed that, the intra-nac shell infusion of ca +2 channel blocker at applied doses, does not alter the anxiety-like response and aversive memory upon test and retest, respectively. furthermore, infusing the subthreshold dose skf prior to the injection of effective doses of nmda, reduced the anxiolytic-like response and improved the aversive memory impairment which had already been induced by intra-nac shell nmda injection. our study showed that,inhibition of the neurotransmitter exocytosis from pre-synaptic neuron via ca +2 channel blockade byskf96365 decreases affected induced by nmda in the nac shell region, indicating the involvement of the pre-synaptic nmda receptors in nmda induced responses.therefore, nmda's ability to increase anxiolytic-like behaviors and the aversive memory impairment may be the result of an action on pre-synaptic glutamatergic receptors which in turn decrease the glutamate effect at synaptic terminal level.