BACKGROUND: Cellular adhesion molecule mediates the effects of glial cell line-derived neurotrophic factor in dopaminergic neurons during nervous system development. It is assumed that cellular adhesion molecule plays an important role in dopaminergic neuron development. OBJECTIVE: To investigate N-cadherin expression in the midbrain substantia nigra during rat development. DESIGN, TIME AND SETTING: The developmental biology, controlled study was performed at the Laboratory of Research Center of Neurobiology, Xuzhou Medical College, China from April to October 2007. MATERIALS: Sprague Dawley rats (embryonic days 16, 18, and 20, as well as postnatal days 1, 3, 7, 14, and 21) were selected for this study. N-cadherin antibody was purchased from Santa Cruz, USA. METHODS: N-cadherin expression in the midbrain substantia nigra of perinatal rats was detected using reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry methods. N-cadherin-positive cells were counted. MAIN OUTCOME MEASURES: N-cadherin mRNA, protein, and positive cells in the rat midbrain substantia nigra were quantified. RESULTS: The results of reverse transcription polymerase chain reaction and Western blot demonstrated that altered N-cadherin mRNA levels were similar to protein levels in the midbrain substantia nigra. N-cadherin mRNA and protein expression was low in the midbrain substantia nigra of embryonic day 16 rats, but gradually increased, and reached a peak at postnatal day 1. N-cadherin mRNA and protein levels were still high at postnatal days 3 and 7, but significantly decreased at postnatal day 14. There was no significant difference in N-cadherin mRNA and protein expression between postnatal days 14 and 21 (P > 0.05). The immunohistochemistry results demonstrated that there was no significant difference in the quantity of N-cadherin-positive cells per area in rats from embryonic day 16 to postnatal day 7 (P > 0.05). The quantity of N-cadherin-positive cells per area was significantly decreased in rats at postnatal day 14. There was no significant difference in the number of N-cadherin-positive cells per area between postnatal days 14 and 21 (P > 0.05). CONCLUSION: N-cadherin expression was reduced during embryonic stages, but reached a peak at postnatal days 1-7, and then gradually decreased in the rat midbrain substantia nigra. BACKGROUND: Cellular adhesion molecule mediates the effects of glial cell line-derived neurotrophic factor in dopaminergic neurons during nervous system development. It is assumed that cellular adhesion molecule plays an important role in dopaminergic neuron development. OBJECTIVE: To investigate N-cadherin expression in the DESIGN, TIME AND SETTING: The developmental biology, controlled study was performed at the Laboratory of Research Center of Neurobiology, Xuzhou Medical College, China from April to October 2007. MATERIALS: Sprague Dawley rats (embryonic days 16 , 18, and 20, as well as postnatal days 1, 3, 7, 14, and 21) were selected for this study. N-cadherin antibody was purchased from Santa Cruz, USA. METHODS: N-cadherin expression in the midbrain substantia nigra of perinatal rats was detected using reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry methods. N-cadherin-positive cells were co unted. MAIN OUTCOME MEASURES: N-cadherin mRNA, protein, and positive cells in the rat midbrain substantia nigra were quantified. RESULTS: The results of reverse transcription polymerase chain reaction and Western blot prototype that altered N-cadherin mRNA levels were similar to protein levels in the midbrain substantia nigra. N-cadherin mRNA and protein expression was low in the midbrain substantia nigra of embryonic day 16 rats, but gradually increased, and reached a peak at postnatal day 1. N-cadherin mRNA and protein levels were still high at postnatal days 3 and 7, but significantly decreased at postnatal day 14. There was no significant difference in N-cadherin mRNA and protein expression between postnatal days 14 and 21 (P> 0.05). The immunohistochemistry results said there was no significant difference in the quantity of N-cadherin-positive cells per area in rats from embryonic day 16 to postnatal day 7 (P> 0.05). The quantity of N-cadherin-positive cells perarea was significantly decreased in rats at postnatal day 14. There was no significant difference in the number of N-cadherin-positive cells per area between postnatal days 14 and 21 (P> 0.05). CONCLUSION: N-cadherin expression was reduced during embryonic stages, but reached a peak at postnatal days 1-7, and then gradually decreased in the rat midbrain substantia nigra.