6. ADRENAL STEROIDS AND ACTH
351
cause histological changes in the adrenal cortex similar to that observed
after metopirone treatment ( Olivereau, 1963a).
Experimental induction of increased circulating adrenal steroids, by
exogenous administration, readily evoked regressive changes in the
adrenal cortex. Such changes included reduction in adrenal cell size and
nuclear diameter (Krauter, 1958; Basu et al., 1965; Hanke and Chester
Jones, 1966; Hanke et al., 1967; Olivereau, 1966) and were reminiscent of
the changes following hypophysectomy. In hypophysectomized eels, cortisol had no further effect upon the regressed adrenal cortex (D. K. 0.
Chan et aZ., 1969).
Cortisol added to the culture medium inhibited the release of ACTH
from cultured goldfish pituitaries (Purrot and Sage, 1967). Similarly in
vivo dexamethasone, a potent blocker of ACTH release in mammals has
been found to reduce circulating cortisol in the rainbow trout. This action
was not the result of a direct action of the drug at the adrenal level since
exogenous ACTH could still stimulate the secretion of cortisol (Donaldson and McBride, 1967; Fagerlund et al., 1968).
D. ACTH in Elasmobranch and Cyclostome Fishes
The pituitary gland of elasmobranch species certainly contains ACTH
activity. Dogfish, Squalus acanthias, skate, Raja rhina, and ratfish, Hydrohgus collieri, neurointermediate lobe and proadenohypophysial extracts
stimulated steroidogenesis by the chicken adrenal cortex incubated in
vitro. The neurointermediate lobe activity was considered to result from
MSH content ( de Roos and de Roos, 1964,1967).
Mammalian ACTH added to the incubation medium of adrenal tissue
of Raja erinacea stimulated the production of blue tetrazolium reducing,
UV absorbing materials, which were probably A4-3-ketosteroids ( Macchi
and Rizzo, 1962). Under similar conditions, the adrenal cortices of three
other species of elasmobranchs (Squalus acanthias, Raja rhinu, and
Hydrohgus collieri) failed to respond to mammalian ACTH (Bern
et al., 1962). Dittus (1941) observed an adrenocortical atrophy after removal of the pituitary in Torpedo sp.
The cyclostomes have been but little examined in respect to ACTH.
Strahan (1959) described an adrenal cortical hypertrophy in mice injected with lamprey pituitary extracts. Erythrosinophils in the lamprey
have been reported to respond to metopirone treatment (Olsson et al.,
1965). Until the adrenal cortex itself is more fully delineated in cyclostomes it is diflicult to determine the existence and interaction of an
adrenocortical-hypophysial axis.
351
cause histological changes in the adrenal cortex similar to that observed
after metopirone treatment ( Olivereau, 1963a).
Experimental induction of increased circulating adrenal steroids, by
exogenous administration, readily evoked regressive changes in the
adrenal cortex. Such changes included reduction in adrenal cell size and
nuclear diameter (Krauter, 1958; Basu et al., 1965; Hanke and Chester
Jones, 1966; Hanke et al., 1967; Olivereau, 1966) and were reminiscent of
the changes following hypophysectomy. In hypophysectomized eels, cortisol had no further effect upon the regressed adrenal cortex (D. K. 0.
Chan et aZ., 1969).
Cortisol added to the culture medium inhibited the release of ACTH
from cultured goldfish pituitaries (Purrot and Sage, 1967). Similarly in
vivo dexamethasone, a potent blocker of ACTH release in mammals has
been found to reduce circulating cortisol in the rainbow trout. This action
was not the result of a direct action of the drug at the adrenal level since
exogenous ACTH could still stimulate the secretion of cortisol (Donaldson and McBride, 1967; Fagerlund et al., 1968).
D. ACTH in Elasmobranch and Cyclostome Fishes
The pituitary gland of elasmobranch species certainly contains ACTH
activity. Dogfish, Squalus acanthias, skate, Raja rhina, and ratfish, Hydrohgus collieri, neurointermediate lobe and proadenohypophysial extracts
stimulated steroidogenesis by the chicken adrenal cortex incubated in
vitro. The neurointermediate lobe activity was considered to result from
MSH content ( de Roos and de Roos, 1964,1967).
Mammalian ACTH added to the incubation medium of adrenal tissue
of Raja erinacea stimulated the production of blue tetrazolium reducing,
UV absorbing materials, which were probably A4-3-ketosteroids ( Macchi
and Rizzo, 1962). Under similar conditions, the adrenal cortices of three
other species of elasmobranchs (Squalus acanthias, Raja rhinu, and
Hydrohgus collieri) failed to respond to mammalian ACTH (Bern
et al., 1962). Dittus (1941) observed an adrenocortical atrophy after removal of the pituitary in Torpedo sp.
The cyclostomes have been but little examined in respect to ACTH.
Strahan (1959) described an adrenal cortical hypertrophy in mice injected with lamprey pituitary extracts. Erythrosinophils in the lamprey
have been reported to respond to metopirone treatment (Olsson et al.,
1965). Until the adrenal cortex itself is more fully delineated in cyclostomes it is diflicult to determine the existence and interaction of an
adrenocortical-hypophysial axis.