Effect of suckling on NADPH-diaphorase (Nitric oxide synthase, NOS) reactivity and NOS gene expression in the paraventricular and supraoptic nuclei of lactating rats |
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Authors: | Otukonyong E E Okere C O Johnstone L E Murata T Kaba H Higuchi T |
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Institution: | Department of Physiology, Kochi Medical School, Nankoku, Kochi, Japan. otukonyo@kochi-ms.ac.jp |
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Abstract: | This study examined the effect of suckling on nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d, a histochemical marker for nitric oxide synthase, NOS) reactivity and neuronal NOS mRNA expression in the paraventricular (PVN) and supraoptic (SON) nuclei of lactating rats. Freely nursing (non-separated) dams and those separated from pups for 12 h and then reunited for 0, 15, 30, 60, 90, 120 and 180 min were used for the study. Dams separated from pups and sacrificed at time zero (without reunion) showed a significant decrease in NADPH-d staining and NADPH-d positive cells as well as in the NOS mRNA expression in the PVN and SON compared to that observed in non-separated dams. Reunion with pups and restoration of suckling significantly increased NADPH-d reactivity after 15, 30, 60 min, but not after 90, 120 and 180 min compared to non-reunited pups-deprived dams. A pattern of NADPH-d reactivity and neuronal NOS mRNA expression indistinguishable from that observed during free lactation was reinstated shortly (15 min) after the restoration of suckling stimulus, suggesting that the NADPH-d reactivity in lactation depends on the presence of the suckling stimulus. These results show that suckling stimulus may play a modulatory role in the regulation of NOS reactivity in the magnocellular neurones of the hypothalamic PVN and SON during lactation. |
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Keywords: | gene expression lactation nitric oxide synthase paraventricular nucleus supraoptic nucleus suckling |
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