Abstract: AIM: To investigate the effects of Ca²⁺ CaM-dependent calcineurin (CaN) signaling pathway on cardiomyocytes hypertrophy of rat induced by neuropeptide Y (NPY).METHODS: Cardiomyocytes of neonatal Wistar rats were cultured with NPY of various concentrations (10, 100 nmol·L^-1).Cyclosporine A (CsA) was used to inhibit the activity of CaN.The methods of 3H-Leu incorporation was used to assess protein synthesis rate in cardiomyocytes.Western-blot and histochemistry were used to measure CaN protein expression and CaN activity in cardiomyocytes.RESULTS: 3H-Leu incorporation of cardiomyocytes were increased significantly by 100 nmol·L^-1NPY (P <0.05) and decreased by CsA.CaN activity and CaN-αprotein expression was elevated markedly in cardiomyocytes by 100 nmol·L^-1NPY (P < 0.05).CONCLUSION: Neuropeptide Y activates Ca²⁺ CaM-dependent calcineurin signal pathway, and CsA can inhibit cardiomyocytes hypertrophy induced by NPY. It indicates that Ca²⁺ CaM-dependent calcineurin (CaN) signaling pathway plays an important role in cardiomyocytes hypertrophy of rats induced by NPY.

Key words: neuropeptide Y, calcineurin, cardiomyocytes hypertrophy