Growth hormone and gro wi
45
this assay,
serial dilutions of serum from intact goldfish show & slope of
inhibition which is parallel to competitive inhibition curves of carp GH
standards, whereas serum from hypophysectomized goldfish does not cross—react
in the RIA.
In addition, the cross—reactivity of serial dilutions of various
mammalian GHS and prolactins, carp gonadotropin, and goldfish prolactin is
negligible or nonexistant (A° Cook gg
1983)° Immunocytochemistry using a
peroxidase—antiperoxidase technique has also demonstrated that the antiserum
to
carp GH used in the RIA reacts only with the secretory granules of cells
in the proximal Eê£Ë distalis of the goldfish pituitary which have been
characterized as
somatotrophs on the basis of several ultrastructural chara—
cteristics
(Ha Cook gg gie, 1983)° These and other results (Cook, 1981; A.:
Cook ʣ
provide firm evidence that the carp GH RIA is specific for
the measurement
of endogenous circulating levels of GH in the goldfish. This
RIA is
the first teleost GH RIA to be fully validated for the measurement of
circulating levels of GH in & teleost
We are
currently using the
carp GH RIA to study the physiology of circulating GH in the goldfish in
order to provide basic information concerning the neural regulation of GH
secretion, and the relationship between blood levels of GH and somatic growth
in & teleost species. We review here recent results of our research in these
areas°
Table
1
Effect of adminstration of rabbit ant:-carp growth hormone serum (HA-cGH) and normal rabbit serum (NHS) on the
’
relative instantaneous growth rate based on changes in body weight in female goldfish.
__________________________________________…___________________________i__
% increase in body weight per week
Pretreatment
Treatment
Treatment
n
Weeks:
1
2
3
4
_________________…_____________________…_______…_______________
NHS
8
1i231t59
15011124*
&DliL61
8611L21
RA-cGH
4
11.17i0.86
12.0411.26
2.5511.94**
All data are meaniS.E.M.
* Significantly different compared to growth rates on week 3 (p<0.01l and on week 4 (p<0.025) of NHS—treated fish.
** Significantly different compared to growth rates on weeks 1 and 2 lp<0.05) of RA-cGH-treatêd fish and of NHS-treated fish on
week 3 (p<0.05).
THE
INFLUENCE OF SEASON ON SERUM GH LEVELS AND GROWTH RATES IN THE GOLDFISH
The rate of body growth has been shown to exhibit a seasonal cycle in
several teleost species, including the common carp (Kawamoto Êt êl., 1957),
the bluegill sunfish, Lepomis macrochirus, (Gerking, 1966), the perch Egrgg
fluviatilis (Le Gren, 1951), northern pike, Eggë lucius, (Diana and Mackay,
1979), brown trout, Salmo t£g££â, (Swift, 1961), various coregonid species
(Hogman, 1968), and several marine teleost species (Shul'man, 1974). All of
these species are found in temperate climatic zones and have a decreased
growth rate in the winter and an increased growth rate in the summer. A
number of variables, including food availability, reproductive activities,
temperature and photoperiod, probably contribute to seasonal changes in
growth rate (Swift, 1961; Gerking, 1966; Shul'man, 1974; Brett, 1979), but
little is known about the role of the endocrine system and, specifically, GH
in the seasonal cycle of body growth. Several morphological studies have pro—
vided evidence that the secretory activity of the somatotrophs may vary on a
seasonal basis
(Scruggs, 1951; Kaul and Vollrath, 1974; Komourdjian 92 al.,
1976). Swift and Pickford (1965) have found that the growth—promoting acti—
Vity of perch
Êl£Eiä£lllä) pituitary glands varies seasonally, and other
45
this assay,
serial dilutions of serum from intact goldfish show & slope of
inhibition which is parallel to competitive inhibition curves of carp GH
standards, whereas serum from hypophysectomized goldfish does not cross—react
in the RIA.
In addition, the cross—reactivity of serial dilutions of various
mammalian GHS and prolactins, carp gonadotropin, and goldfish prolactin is
negligible or nonexistant (A° Cook gg
1983)° Immunocytochemistry using a
peroxidase—antiperoxidase technique has also demonstrated that the antiserum
to
carp GH used in the RIA reacts only with the secretory granules of cells
in the proximal Eê£Ë distalis of the goldfish pituitary which have been
characterized as
somatotrophs on the basis of several ultrastructural chara—
cteristics
(Ha Cook gg gie, 1983)° These and other results (Cook, 1981; A.:
Cook ʣ
provide firm evidence that the carp GH RIA is specific for
the measurement
of endogenous circulating levels of GH in the goldfish. This
RIA is
the first teleost GH RIA to be fully validated for the measurement of
circulating levels of GH in & teleost
We are
currently using the
carp GH RIA to study the physiology of circulating GH in the goldfish in
order to provide basic information concerning the neural regulation of GH
secretion, and the relationship between blood levels of GH and somatic growth
in & teleost species. We review here recent results of our research in these
areas°
Table
1
Effect of adminstration of rabbit ant:-carp growth hormone serum (HA-cGH) and normal rabbit serum (NHS) on the
’
relative instantaneous growth rate based on changes in body weight in female goldfish.
__________________________________________…___________________________i__
% increase in body weight per week
Pretreatment
Treatment
Treatment
n
Weeks:
1
2
3
4
_________________…_____________________…_______…_______________
NHS
8
1i231t59
15011124*
&DliL61
8611L21
RA-cGH
4
11.17i0.86
12.0411.26
2.5511.94**
All data are meaniS.E.M.
* Significantly different compared to growth rates on week 3 (p<0.01l and on week 4 (p<0.025) of NHS—treated fish.
** Significantly different compared to growth rates on weeks 1 and 2 lp<0.05) of RA-cGH-treatêd fish and of NHS-treated fish on
week 3 (p<0.05).
THE
INFLUENCE OF SEASON ON SERUM GH LEVELS AND GROWTH RATES IN THE GOLDFISH
The rate of body growth has been shown to exhibit a seasonal cycle in
several teleost species, including the common carp (Kawamoto Êt êl., 1957),
the bluegill sunfish, Lepomis macrochirus, (Gerking, 1966), the perch Egrgg
fluviatilis (Le Gren, 1951), northern pike, Eggë lucius, (Diana and Mackay,
1979), brown trout, Salmo t£g££â, (Swift, 1961), various coregonid species
(Hogman, 1968), and several marine teleost species (Shul'man, 1974). All of
these species are found in temperate climatic zones and have a decreased
growth rate in the winter and an increased growth rate in the summer. A
number of variables, including food availability, reproductive activities,
temperature and photoperiod, probably contribute to seasonal changes in
growth rate (Swift, 1961; Gerking, 1966; Shul'man, 1974; Brett, 1979), but
little is known about the role of the endocrine system and, specifically, GH
in the seasonal cycle of body growth. Several morphological studies have pro—
vided evidence that the secretory activity of the somatotrophs may vary on a
seasonal basis
(Scruggs, 1951; Kaul and Vollrath, 1974; Komourdjian 92 al.,
1976). Swift and Pickford (1965) have found that the growth—promoting acti—
Vity of perch
Êl£Eiä£lllä) pituitary glands varies seasonally, and other