52
TA. Merchant et al.
PERSPECTIVES
Research on the physiology of GH in teleosts is in a preliminary stage.
In the goldfish, we have only just started to examine some of the aspects
pertaining to the relationship between GH and body growth. Further studies in
every area related
to
GH, including the influence of environment on GH and
growth, the neural regulation of GH secretion, the mechanism of action of GH,
and interaction with other hormones
such as
thyroid hormones, steroids and
pancreatic hormones, are required in goldfish and other teleosts before a
clear picture concerning the physiology of GH emerges. Of primary interest to
aquaculturists will be studies in which the rate of body growth can be
influenced by alterations in circulating levels of GH. The results outlined
above indicate that increased blood levels of GH do have a stimulatory
influence on body growth. However, our results also indicate that increased
growth rates do not necessarily require high circulating levels of GH. Nevertheless, it is probable that use of environmental manipulations as well as
manipulation of hypothalamic neuroendocrine mechanisms regulating GH secre—
tion wi11 prove
to
be fruitful methods of stimulating increased blood levels
of GH and, consequently, increased body growth rates in teleosts.
LITERATURE CITED
Adelman, I.R. 1977° Effects of bovine growth hormone on growŒh of carp
(Cyprinus carpio) and the influences of temperature and photoperiod.
J.
Fish.
Res.
Board Can.
â3:509—515.
Andrews, P.C. and J.E. Dixon. 1981. Isolation and characterization of &
peptide hormone predicted from a mRNA sequence. A second somatostatin
from the catfish pancreas. J.
Biol.
Chem.
ggg: 8267—8270.
Arimura, A. and M.D. Culler. 1985° Regulation of growth hormone secretion.
In:
H.
Imura
(Ed), The Pituitary Gland, Raven Press, New York, 221—259.
Ball, J.N. 1981. Hypothalamic control of the pars distalis in fishes, amphibians and reptiles. Gen. Comp. Endocrinol. &&: 135—170.
Ball, J.N. and E.F. Hawkins. 1976. Adrenocortical (interrenal) responses to
hypophysectomy and adenohypophyseal hormones in the teleost Poecilia
latipinna. Gen. Comp. Endocrinol. gg: 59—70.
Brett, J.R. 1979. Environmental factors and growth. In: W.S. Hear, D.J.
Randall and J.R.
Brett, Fish Physiology, Vol. VIII, Bioenergetics and
Growth, Academic Press, New York, 599—675.
Carillo, M.A., S. Zanuy, J. Kuo, and W. Watanabe. 1980. Daily rhythms of
liver CAMP, total liver lipids, prolactin—like hormone, and gr0Wth horm—
one
cell activities in Sarotherodon mossambicus acclimated to different
photoperiod regimes. Gen. Comp. Endocrinol.
325—333.
Chang, J.P., T.A. Marchant, A.F. Cook, C.S. Nahorniak and R.E. Peter. 1985Influences of catecholamiues on growth hormone release in female
goldfish, Carassius auratus. Neuroendocrinology 40: 463—470.
Clarke, W.C., S.W. Farmer and K.M. Hartwell. 1977. Effect of teleost pituitary growth hormone on growth of Tilapia mossambicus and on growth and
sea
water
adaptation of sockeye salmon (Oncorhynchus nerka). Gen. CompEndocrinol.
à}: 174—178.
Cook, A.F. 1981. Validation of a growth hormone radioimmunoassay and its
application to neuroendocrine studies in the goldfish Carassius auratus—
Ph.D.
Thesis, Department of Zoology, University of Alberta:_Edmonton,
Canada, 1—191.
Cook, A.F. and R-E. Peter. 1983. Effects of hypothalamic lesions on serum
growth hormone levels and growth rates in the goldfish, Carassius
auratus.
Gen.
Comp. Endocrinol. â1: 175—182.
TA. Merchant et al.
PERSPECTIVES
Research on the physiology of GH in teleosts is in a preliminary stage.
In the goldfish, we have only just started to examine some of the aspects
pertaining to the relationship between GH and body growth. Further studies in
every area related
to
GH, including the influence of environment on GH and
growth, the neural regulation of GH secretion, the mechanism of action of GH,
and interaction with other hormones
such as
thyroid hormones, steroids and
pancreatic hormones, are required in goldfish and other teleosts before a
clear picture concerning the physiology of GH emerges. Of primary interest to
aquaculturists will be studies in which the rate of body growth can be
influenced by alterations in circulating levels of GH. The results outlined
above indicate that increased blood levels of GH do have a stimulatory
influence on body growth. However, our results also indicate that increased
growth rates do not necessarily require high circulating levels of GH. Nevertheless, it is probable that use of environmental manipulations as well as
manipulation of hypothalamic neuroendocrine mechanisms regulating GH secre—
tion wi11 prove
to
be fruitful methods of stimulating increased blood levels
of GH and, consequently, increased body growth rates in teleosts.
LITERATURE CITED
Adelman, I.R. 1977° Effects of bovine growth hormone on growŒh of carp
(Cyprinus carpio) and the influences of temperature and photoperiod.
J.
Fish.
Res.
Board Can.
â3:509—515.
Andrews, P.C. and J.E. Dixon. 1981. Isolation and characterization of &
peptide hormone predicted from a mRNA sequence. A second somatostatin
from the catfish pancreas. J.
Biol.
Chem.
ggg: 8267—8270.
Arimura, A. and M.D. Culler. 1985° Regulation of growth hormone secretion.
In:
H.
Imura
(Ed), The Pituitary Gland, Raven Press, New York, 221—259.
Ball, J.N. 1981. Hypothalamic control of the pars distalis in fishes, amphibians and reptiles. Gen. Comp. Endocrinol. &&: 135—170.
Ball, J.N. and E.F. Hawkins. 1976. Adrenocortical (interrenal) responses to
hypophysectomy and adenohypophyseal hormones in the teleost Poecilia
latipinna. Gen. Comp. Endocrinol. gg: 59—70.
Brett, J.R. 1979. Environmental factors and growth. In: W.S. Hear, D.J.
Randall and J.R.
Brett, Fish Physiology, Vol. VIII, Bioenergetics and
Growth, Academic Press, New York, 599—675.
Carillo, M.A., S. Zanuy, J. Kuo, and W. Watanabe. 1980. Daily rhythms of
liver CAMP, total liver lipids, prolactin—like hormone, and gr0Wth horm—
one
cell activities in Sarotherodon mossambicus acclimated to different
photoperiod regimes. Gen. Comp. Endocrinol.
325—333.
Chang, J.P., T.A. Marchant, A.F. Cook, C.S. Nahorniak and R.E. Peter. 1985Influences of catecholamiues on growth hormone release in female
goldfish, Carassius auratus. Neuroendocrinology 40: 463—470.
Clarke, W.C., S.W. Farmer and K.M. Hartwell. 1977. Effect of teleost pituitary growth hormone on growth of Tilapia mossambicus and on growth and
sea
water
adaptation of sockeye salmon (Oncorhynchus nerka). Gen. CompEndocrinol.
à}: 174—178.
Cook, A.F. 1981. Validation of a growth hormone radioimmunoassay and its
application to neuroendocrine studies in the goldfish Carassius auratus—
Ph.D.
Thesis, Department of Zoology, University of Alberta:_Edmonton,
Canada, 1—191.
Cook, A.F. and R-E. Peter. 1983. Effects of hypothalamic lesions on serum
growth hormone levels and growth rates in the goldfish, Carassius
auratus.
Gen.
Comp. Endocrinol. â1: 175—182.