Aims: 

Tridecapeptide Neurotensin (NT) in the central nervous system acts as a neurotransmitter and neuromodulator. It has been shown that there is a relationship between malfunction of the NT system and several neurologic and psychiatric diseases, i.e: schizophrenia, Parkinson's disease, mood disorders and drug addiction. NT has been proven to have positive reinforcing effects in the ventral tegmental area and it can modify the place learning process in the nucleus accumbens. The central nucleus of amygdala (CeA), part of the limbic system, plays an important role in learning, memory, anxiety and reinforcing mechanisms. The aimm of our study was to examine in the CeA the possible effects of NT on reinforcement in conditioned place preference test and on anxiety in elevated plus maze test.

Methods: 

Male Wistar rats were microinjected bilaterally with 100 ng NT or 250 ng NT (Sigma: N 3010, injected in volume of 0.4 ml). Other animals have received 35 ng NT-1 receptor (NTS1) antagonist SR 48692 (Sanofi) alone, or NTS1 antagonist 15 min before 100 ng NT treatment or vehicle solution into the CeA.

Results: 

In the conditioned place preference test 100 ng NT and/or 250 ng NT significantly increased the time rats spent in the treatment quadrant. Prior treatment with NTS1 antagonist blocked the effects of NT. Antagonist in itself did not influence the place preference. In the elevated plus maze we did not find differences among the groups as far as the anxiety index (time spent on the open arms) was concerned.

Conclusion: 

Our results show that in the rat CeA, NT has positive reinforcing effect via NTS1, because selective NTS1 antagonist can block this action. It was also indicated that NT does not influence anxiety behaviour.

Support: 

NKTH-OTKA K68431 and by the HAS