TY - JOUR
T1 - Relaxin counteracts the altered gastric motility of dystrophic (mdx) mice
T2 - Functional and immunohistochemical evidence for the involvement of nitric oxide
AU - Vannucchi, M. G.
AU - Garella, R.
AU - Cipriani, G.
AU - Baccari, M. C.
PY - 2011/2
Y1 - 2011/2
N2 - Impaired gastric motility ascribable to a defective nitric oxide (NO) production has been reported in dystrophic (mdx) mice. Since relaxin upregulates NO biosynthesis, its effects on the motor responses and NO synthase (NOS) expression in the gastric fundus of mdx mice were investigated. Mechanical responses of gastric strips were recorded via force displacement transducers. Evaluation of the three NOS isoforms was performed by immunohistochemistry and Western blot. Wild-type (WT) and mdx mice were distributed into three groups: untreated, relaxin pretreated, and vehicle pretreated. In strips from both untreated and vehicle-pretreated animals, electrical field stimulation (EFS) elicited contractile responses that were greater in mdx than in WT mice. In carbachol-precontracted strips, EFS induced fast relaxant responses that had a lower amplitude in mdx than in WT mice. Only in the mdx mice did relaxin depress the amplitude of the neurally induced excitatory responses and increase that of the inhibitory ones. In the presence of L-NNA, relaxin was ineffective. In relaxin-pretreated mdx mice, the amplitude of the EFS-induced contractile responses was decreased and that of the fast relaxant ones was increased compared with untreated mdx animals. Responses to methacholine or papaverine did not differ among preparations and were not influenced by relaxin. Immunohistochemistry and Western blotting showed a significant decrease in neuronal NOS expression and content in mdx compared with WT mice, which was recovered in the relaxin-pretreated mdx mice. The results suggest that relaxin is able to counteract the altered contractile and relaxant responses in the gastric fundus of mdx mice by upregulating nNOS expression.
AB - Impaired gastric motility ascribable to a defective nitric oxide (NO) production has been reported in dystrophic (mdx) mice. Since relaxin upregulates NO biosynthesis, its effects on the motor responses and NO synthase (NOS) expression in the gastric fundus of mdx mice were investigated. Mechanical responses of gastric strips were recorded via force displacement transducers. Evaluation of the three NOS isoforms was performed by immunohistochemistry and Western blot. Wild-type (WT) and mdx mice were distributed into three groups: untreated, relaxin pretreated, and vehicle pretreated. In strips from both untreated and vehicle-pretreated animals, electrical field stimulation (EFS) elicited contractile responses that were greater in mdx than in WT mice. In carbachol-precontracted strips, EFS induced fast relaxant responses that had a lower amplitude in mdx than in WT mice. Only in the mdx mice did relaxin depress the amplitude of the neurally induced excitatory responses and increase that of the inhibitory ones. In the presence of L-NNA, relaxin was ineffective. In relaxin-pretreated mdx mice, the amplitude of the EFS-induced contractile responses was decreased and that of the fast relaxant ones was increased compared with untreated mdx animals. Responses to methacholine or papaverine did not differ among preparations and were not influenced by relaxin. Immunohistochemistry and Western blotting showed a significant decrease in neuronal NOS expression and content in mdx compared with WT mice, which was recovered in the relaxin-pretreated mdx mice. The results suggest that relaxin is able to counteract the altered contractile and relaxant responses in the gastric fundus of mdx mice by upregulating nNOS expression.
KW - Mechanical responses
KW - Muscular dystrophy
KW - Nitric oxide synthase
KW - Stomach
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U2 - 10.1152/ajpendo.00375.2010
DO - 10.1152/ajpendo.00375.2010
M3 - Article
C2 - 21081707
AN - SCOPUS:79251542341
SN - 0193-1849
VL - 300
SP - E380-E391
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 2
ER -