Abstract |
It is well established that growth hormone (GH) is secreted in a pulsatile manner. Although the GH pulse-generating mechanism is not fully understood, we have previously reported that neuropeptide Y (NPY) profiles in the cerebrospinal fluid were negatively correlated with serum GH pulses. In addition, it is known that photic stimulation suppresses GH pulses for a certain period of time. In the present study, to investigate the involvement of NPY in regulating GH pulse generation, NPY gene expression in the arcuate nucleus ( ARC) of the hypothalamus in rats was analyzed at around the lights on. First, we confirmed that GH pulses did not occur for around 1.5 hr after the start of the light phase. Then, we analyzed the activity of neurons and expression of NPY mRNA 1 hr before and 0.5 and 2 hr after lights on. Both the activity of neurons, which was evaluated by immunohistochemical detection for phosphorylated- cAMP response element binding protein (pCREB), and NPY mRNA levels in the caudal ARC were higher at 0.5 hr after lights on than the other two time points, while pCREB-positive cell numbers in the rostral ARC remained unchanged throughout the experimental period. In addition, NPY immunoreactivity in the periventricular nucleus (PeVN) was also higher at 0.5 hr after lights on than the other time points. These results suggest that NPY neurons in the caudal ARC projecting to the PeVN play a role in inhibiting GH pulses at the commencement of the light phase.
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Authors | Ayano Fujisawa, Takashi Matsuwaki, Keitaro Yamanouchi, Masugi Nishihara |
Journal | The Journal of veterinary medical science
(J Vet Med Sci)
Vol. 75
Issue 3
Pg. 275-81
( 2013)
ISSN: 1347-7439 [Electronic] Japan |
PMID | 23090692
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Cyclic AMP Response Element-Binding Protein
- Neuropeptide Y
- RNA, Messenger
- Growth Hormone
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Topics |
- Animals
- Arcuate Nucleus of Hypothalamus
(metabolism)
- Cyclic AMP Response Element-Binding Protein
(genetics, metabolism)
- Gene Expression Regulation
(physiology)
- Growth Hormone
(metabolism)
- Light
- Male
- Midline Thalamic Nuclei
- Neurons
- Neuropeptide Y
(metabolism)
- RNA, Messenger
(genetics, metabolism)
- Rats
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