Abstract: Objective To observe the protein expression of growth associated protein-43 （GAP-43） in midbrain ventral tegmental area in morphine withdrawal rats at different time, and to evaluate the effect of GAP-43 on morphine withdrawal memory. Methods Rat models of morphine dependent 1 week, 2 weeks and 4 weeks were established by morphine hydrochloride intraperitoneal injection with increasing doses to establish natural withdrawal. The protein expression of GAP-43 in midbrain ventral tegmental area was observed by immunohistochemical staining and the results were analyzed by Image-Pro Plus 5.1 image analysis system. Results With prolongation of dependent time, the expression of GAP-43 was decreased then increased in midbrain ventral tegmental area. Conclusion GAP-43 could play a role in morphine withdrawal memory in midbrain ventral tegmental area.

Key words: forensic pathology, morphine dependence, growth associated protein-43, rats