Biochemical and Biophysical Research Communications
Effects of neuromedin U on the pulsatile LH secretion in ovariectomized rats in association with feeding conditions
Section snippets
Materials and methods
Animals. Female rats of Wistar strain (Charles River, Yokohama, Japan) were obtained at 7 weeks of age and maintained under controlled lighting conditions (lights on 05:00–19:00 h) with food and water available ad libitum. They were ovariectomized (OVX) and, for the intracerebroventricular (icv) injection, stereotaxically implanted with a guide cannula into the third ventricle according to the atlas of Albe-Fessard et al. [24] (stereotaxic coordinates: A=6.0, V=2.0, and L=0.0) under sodium
Experiment 1
Fig. 1 shows representative individual LH profiles and the mean LH concentration before and after icv injection of aCSF or NMU in OVX rats under the normal feeding condition. The pulsatile fluctuation of serum LH was evident during the blood sampling in aCSF-injected OVX rats, suggesting that icv injection of aCSF had no significant effect on the pulsatile LH secretion. NMU injection, on the other hand, seemed to inhibit the pulsatile LH secretion, since the serum LH concentration at the
Discussion
The present study shows for the first time that the central administration of NMU inhibits the pulsatile LH secretion and this effect is significantly enhanced under the 48-h fasted condition, which by itself does not markedly affect the pulsatile LH secretion. Since satiety factors such as leptin and glucagon-like peptide-1 stimulate the LH secretion [21], [23], while orexinergic factors such as ghrelin, orexin, and melanin-concentrating hormone inhibit it [15], [16], [28], the inhibitory
Acknowledgements
We are grateful to Dr. K. Wakabayashi of Gunma University School of Medicine and the NIDDK for providing radioimmunoassay materials.
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Estradiol suppresses NMU mRNA expression during sexual maturation in the female rat pituitary
2008, International Journal of Developmental NeuroscienceCitation Excerpt :While one experiment reported that intracerebroventricular NMU administration did not affect luteinizing hormone (LH) plasma levels in male rats (Gartlon et al., 2004), others showed that NMU had some effects on the pituitary gland and the reproductive system. For example, administration of NMU into the third ventricle inhibited pulsatile LH secretion in adult ovariectomized rats (Quan et al., 2003). NMU has also been shown to suppress LH secretion from cultured rat anterior pituitary cells.
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