RESUMEN
Previous reports showed that nucleus accumbens involved in the etiology and pathophysiology of major depression, anxiety and addiction. It is not clear that how these mechanisms occur in the brain. In the present study, the influence of direct nicotine injection in the nucleus accumbens in rats' anxiety-related behavior was investigated. Wistar rats were used in this study. Male Wistar rats bred in an animal house, in a temperature-controlled [22 +/- 2[degree]C] room with a 12 hour light/darkcycle. Rats were anesthetized using intraperitoneal injection of ketamine hydrochloride and xylazine, then placed in an stereotactic instrument for microinjection cannula implantation The stainless steel guide cannula was implanted bilaterally in the right and left dorsal the nucleus accumbens shell according to Paxinos and Watson atlas. After recovery, anxiety behavior and locomotor activity were tested. We used the elevated plus maze to test anxiety. This apparatus has widely been employed to test parameters of anxietyrelated behaviors including the open armtime percentage [%OAT], open arm entries percentage [%OAE], locomotor activity and we record effect of drugs after injection directly in the nucleus accumbens on anxiety-related behavior. Experiments showed that bilateral injections into the nucleus accumbens Nicotine, acetylcholine receptor agonist, dose 0.1 of the dose [0.05 and 0.1, 0.25, 0.5] microgram per rat caused a significant increase in the percentage of time spent in the open arms [%OAT], compared to the control group. We did not record any significant change locomotor activity and open arm entries percentage [%OAE] in rats. Nicotinic receptors in the nucleus accumbens shell involved to anxietylike behavior in male rats.