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Vol. 36 No. 2, 1997
Review Article
Neuroendocrine Regulation of Growth Hormone Secretion and
Growth in Fish
Chun
Peng1 and Richard E. Peter2,*
1Department
of Biology, York University, North York, Ontario M3J 1P3, Canada
2Department of Biological Sciences,
University of Alberta, Edmonton, Alberta T6G 2E9, Canada
Chun Peng and Richard E. Peter (1997)
Neuroendocrine regulation of growth hormone secretion and growth in
fish. Zoological Studies 36(2): 79-89. Growth in fish is regulated in
large part by the brain neuroendocrine - growth hormone (GH) -
insulin-like growth factor axis. GH secretion is in turn regulated by
multiple factors from the .brain, with both stimulatory and inhibitory
neurohormones acting on the somatotrophs seasonally.
Somatostatin is the primary inhibitor of basal and stimulated GH
secretion . Norepinephrine and serotonin also have inhibitory actions
on GH release. On the other hand, GH secretion is stimulated by a
number of neuroendocrine factors, including growth hormone-releasing
factor (GRF), dopamine (DA), gonadotropin-releasing hormone (GnRH),
neuropeptide Y (NPY), thyrotropin-releasing hormone (TRH),
cholecystokinin (CCK), bombesin (BBS), and activin . While GRF and DA
are more potent in stimulating GH secretion in sexually regressed fish,
GnRH, NPY, and TRH have greater stimulatory effects on GH secretion in
sexually mature (l.a., prespawning) fish. Sex steroids, in particular
estradiol, influence the responsiveness of the somatotrophs to
neuroendocrine factors. The integrated action of sex steroids and
neuroendocrine factors provides a basis for the seasonal regulation of
growth hormone secretion.
The brain peptide systems regulating food intake are linked to the
brain neuroendocrine regulation of GH secretion. Following a meal,
goldfish characteristically show a short-term increase in serum GH
concentrations, and then a decrease in serum GH concentrations to below
premeal levels. BBS and CCK are involved in satiation and the changes
in GH secretion following a meal in goldfish . Both the neuroendocrine
regulation of GH secretion and the brain regulation of feeding are
multifactor ial. Understanding the integration of these systems
presents a major challenge .
Key words: Fish,
Growth hormone, Food intake, Neuropeptide , Monoamine.
*Correspondence: Tel: (403) 492-4757, Fax: (403) 492-7033,
E-mail: REPeter@sci.ualberta.ca
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