Possible Involvement of Neuropeptide Y in Photo-Induced Suppression of Growth Hormone Pulses

Access this Article

Author(s)

    • FUJISAWA Ayano
    • Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo 113–8757, Japan
    • MATSUWAKI Takashi
    • Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo 113–8757, Japan
    • YAMANOUCHI Keitaro
    • Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo 113–8757, Japan
    • NISHIHARA Masugi
    • Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo 113–8757, Japan

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.

Journal

  • Journal of Veterinary Medical Science

    Journal of Veterinary Medical Science 75(3), 275-281, 2013

    JAPANESE SOCIETY OF VETERINARY SCIENCE

Codes

  • NII Article ID (NAID)
    130001879650
  • Text Lang
    ENG
  • ISSN
    0916-7250
  • Data Source
    J-STAGE 
Page Top