اثر غيرفعال سازي برگشت پذير هسته لوكوس سروليوس بر يادگيري و حافظه موش سفيد بزرگ آزمايشگاهي با استفاده از روش يادگيري احترازي غيرفعال

Inactivation of Locus Coeruleus Using Passive Avoidance Tasks in Rats

The brain pontine nucleus, the locus coeruleus (LC) is involved in processes like pain, vigilance, learning, and memory (L & M). The role of LC in L & M has been a matter of debate for several years. In the present study the involvement of LC in acquisition, consolidation and memory in male albino rats using passive avoidance learning (PAL) tasks was investigated. Injections of 0.5111 saline or lidocaine (4%) were administrated into the locus coeruleus 5 min before and 5, 90 and 360 mins after acquisition of PAL and 5 min before retention tests. Retention tests were performed 48 hrs after training. Data showed that LC inactivation before acquistion did not affect PAL learning but impaired its retention (P<0.001). On the other hand, LC inactivation after training, time dependently impaired PAL consolidation. Only those rats that received lidocaine 5 mins after training showed memory deficits in comparison with the saline group (P<0.01). Inactivation of LC, 5 min before retention tests, impaired memory retrieval in the lidocaine group in comparison with the saline group (P<0.001). Furthermore, reversible inactivation of LC did not affect the normal locomotor activity of the experimental groups. In conclusion, it seems that locus coeruleus has no significant effect on PAL acquisition but involves in its consolidation and retrieval, which is suggestive of the role of LC noradrenergic neurons in the memory processes.