Preliminary Study On Stereotactic Nuclear Lesion In Cocaine Addictive Rats

Objective: To observe the morphological changes in brain region in cocaine addictive and stereotaxic nuclear lesion rats and to determine the level of monoamine neurotransmitter to explore the effects of stereotaxic nuclear lesion methods in abstaining cocainism in cocaine addictive rats.Methods: The study adopted 48 SD rats as the observed animals divided randomly into six groups. Group A: the control group (n=8), group B: addiction group (sham lesion group, n=8), group C: lesion nucleus accumbens group (n=8), group D: lesion hippocampus group (n=8), group E: lesion cingulated cortex group (n=8), group F: lesion nucleus accumbens, hippocampus and cingulated cortex group (n=8). The rats in control group were given 0.2ml saline subcutaneously daily for 90 days. The others were given 0.2ml cocaine hydrochloride (15mg/kg) subcutaneously daily for 90 days. Except 8 rats in group B as addiction group with sham lesion, the other 32 rats in group C,D,E,F were operated in different nuclear or brain region with stereotaxic direct current electrolytic lesion surgery. 3days later after lesion, the lesion rats all killed to be determined the level of monoamine neurotransmitter including DA, 5-HT and their metabolite DOPAC, HVA in nucleus accumbens with HPLC-ECD. We also observed and compared the morphological changes in brain regions of normal, addiction, lesion rat under light and electron microscopy. Result: The level of dopamine in nucleus accumbens of addiction rat increased significantly comparing with that of the control rat (P<0.01). The level of monoamine neurotransmitter in nucleus accumbens of lesion rat was no significant different comparing with that of the addictive rats with sham lesion. We found light and electron microscopic changes in hippocampus, nucleus accumbens and cingulated cortex, including nuclear pyknosis, interstitial edema, broken fiber and necrosis.Conclusion: Long term cocaine exposure can lead to injure in different brain regions and cause significant rising of dopamine level in nucleus accumbens. The level of monoamine neurotransmitter is not an effective marker to show the role of stereotaxic nuclear lesion methods in abstaining cocainism in cocaine addictive rats.