Alteration Level of Hippocampus BDNF Expression and Long Term Potentiation Following Microinjection 5-HT1F Receptor Agonist in the Reinstatement of Methamphetamine Behavior

Methamphetamine’s (METH) reinstatement affects the function of the serotonergic system that it is important for brain-derived neurotrophicfactor (BDNF) level and synaptic plasticity. At the moment, the physiological function of 5-HT1F receptor is unknown although the distribution of this receptor in the memory and reward regions is known. Herein, agonist effects of this receptor (LY 344864) on behavior, longtermpotentiation (LTP) and BDNF level in reinstated METH-rats were assessed. Materials and Methods: Conditioned place preference induced by the injection of METH (5mg/kg; i.p) or saline on the conditioning days. On the last day of extinction, rats obtained METH [Simultaneously with LY (2μg/5μl; i.c.v) or vehicle]. In control or sham groups, rats received Saline or Saline +vehicle instead methamphetamine, respectively. On the reinstatement day, preference scores were calculated. Then, electrophysiology and western blotting methods were performed for measurements LTP components, and expression of BDNF, respectively. Results: The results showed the conditioning scores of primingMETH treatment significantly increased more than other groups and pre-treatment with LY significantly reduced the reinstatement of priming METH seeking. Furthermore, PS amplitude and EPSP slope in vehicle +priming METH rats were more than others. Also, PS amplitude in LY + METH group was lower than priming METH group. Likewise, BDNF expression considerably increased in METH group although treatment with LY was no different to sham group. Conclusion: These results suggest serotoninergic system plays regulatory roles in synaptic plasticity and there is the vital effect of synergism among these systems in METH-reinstatement behaviors.