Effects of heroin dependence on the expression of L‐ENK and SS in the VTA and NAc regions of rat brain

Abstract

To investigate the effect of the heroin addicts on ratˈs L‐ENK‐ ¡¢SS‐immunoreactive cells in the ventral tegmental area(VTA) and nucleus accumbens(NAc) regions, and exploring the effect of heroin dependence on learning and memory mechanisms. Adulthood 55 male SD rats were randomly divided into normal control group(NCG), saline control group(SCG) and the heroin‐dependent group(HDG). Heroin‐dependent rat models were set up by the way of subcutaneous injection of heroin and brain tissues are excised on the 10th, 17th, 24th, 31th, and 38th days after models are set up. Immunohistochemical staining was performed to test the expression of L‐ENK and SS in the VTA and NAc regions. The expression of L‐ENK and SS was observed as brown yellow particle in the cytoplasm of neurons in the VTA and NAc regions. L‐ENK‐immunoreactive cells and SS‐immunoreactive cells expressed less L‐ENK and SS in the VTA and NAc regions from HDG rats than that from SCG and NCG rats at different time points. Immunohistochemical analysis showed higher grey value was found in HDG rats than that in controls (p<0.05). The results suggest that the secretion of L‐ENK and SS is inhibited during heroin dependence, and heroin dependence may cause damage to learning and memory function.