Modelling the Hypothalamic Control of Growth Hormone Secretion

Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, George Square, Edinburgh, UK.
Journal of Neuroendocrinology (Impact Factor: 3.51). 01/2006; 17(12):788-803. DOI: 10.1111/j.1365-2826.2005.01370.x
Source: PubMed

ABSTRACT Here, we construct a mathematical model of the hypothalamic systems that control the secretion of growth hormone (GH). The work extends a recent model of the pituitary GH system, adding representations of the hypothalamic GH-releasing hormone (GHRH) and somatostatin neurones, each modelled as a single synchronised unit. An unpatterned stochastic input drives the GHRH neurones generating pulses of GHRH release that trigger GH pulses. Delayed feedback from GH results in increased somatostatin release, which inhibits both GH secretion and GHRH release, producing an overall pattern of 3-h pulses of GH secretion that is very similar to the secretory profile observed in male rats. Rather than directly stimulating somatostatin release, GH feedback triggers a priming effect, increasing releasable stores of somatostatin. Varying this priming effect to reduce the effect of GH can reproduce the less pulsatile form of GH release observed in the female rat. The model behaviour is tested by comparison with experimental observations with a range of different experimental protocols involving GHRH injections and somatostatin and GH infusion.

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    • "Besides the oxytocin model reviewed above, there are mathematical models of the pulsatile secretion of LHRH (Gordan et al., 1998; Scullion et al., 2004; Khadra and Li, 2006), the hypothalamic control of growth hormone secretion (MacGregor and Leng, 2005), and the bursting properties of vasopressin (Roper et al., 2004), etc. The recent model for LHRH revealed that LHRH plays the roles of feedback regulator and a diffusive synchronization effects in pulsatile secretion of LHRH from hypothalamic neurons. "
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