Exp Neurobiol 2004; 13(1): 47-56

Published online July 1, 2004

© The Korean Society for Brain and Neural Sciences

Modeling Ultradian Rhythmicity of the Hypothalamic GnRH Neurosecretory Cells

Kihyuk Han1*, Sukwon Lee1, Junehee Park1, Gi Hoon Son1, Inkoo Khang, Kun Ho Lee1, Chung Choo Lee2and Kyungjin Kim1

1School of Biological Sciences, Seoul National University,Seoul 151-742, Korea, 2Division of Biological Sciences,Gachon Medical School, Ganghwa 417-980, Korea

Correspondence to: *To whom correspondence should be addressed.
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Pulsatile secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus is crucial for the neuroendocrine regulation of pituitary function in the hypothalamic- pituitary-gonadal axis. The origin and molecular nature of GnRH pulsatility are, however, still unknown. In the present study, we simulated the ultradian rhythmicity by in silico modeling approach. Based on the recent study in which pulsatile secretion of GnRH is originated from transcriptional oscillation, a negative feedback-based self-oscillation model at the levels of GnRH mRNA and GnRH secretion was formulated. Furthermore, this model was expanded to examine the network effect with 100 synaptically interconnected neurons. This model exhibits ultradian rhythmicity and synchronization effect as com-pared to the randomly firing network model. This in silico approach appears to be valuable in elucidating the molecular nature and origin of biorhythmicity in the complex GnRH neuronal apparatus.

Keywords: Hypothalamus, GnRH, pulsatility, neural network model, negative feedback, gene expression-secretion coupling, oscillation