6. ADRENAL STEROIDS AND ACTH
329
precursors such as acetate, cholesterol, pregnenolone, or progesterone.
After a period of time the incubation medium is analyzed for steroids
formed from the precursors, and the conversion pattern of the known
steroid precursors to adrenocorticosteroids may be constructed (see
Hechter and Pincus, 1954; Dorfman, 1962).
Of the 23,OOO species of fishes, only a few have been used in such
steroid biogenetic studies. In elasmobranch fish, the adrenal gland is
homogeneous and well defined, but in all other species it has not yet been
possible to isolate the gland free from other tissue contaminants (head
kidney, connective tissue, and renal tissue). Nevertheless, in vitro incubation studies have yielded valuable information, which often correlates
with the steroid pattern present in plasma. Fish tissue usually contains
sufficient quantities of adrenocortical tissue to convert pregnenolone or
progesterone to adrenocorticosteroids in vitro. The biosynthetic pathways
and the final products obtained may differ from species to species and
from class to class.
Cardinal veins, containing the adrenocortical tissue of the eel, Anguillu
angzcilk, readily converted labeled progesterone and pregnenolone to
cortisol and cortisone (Butler, 1965; Sandor et d., 1966; Leloup-Hatey,
1966). In homogenates of the same tissues cholesterol has also been used
as a precursor for the adrenocorticosteroids of the eel (Sandor et al.,
1967). ll-Deoxycortisol was also isolated from this latter preparation.
Whether corticosterone is present as an intermediate in adrenmrticosteroid biosynthesis in the eel is in doubt. In this species, 17-hydroxylation
is very efficient. Added pregnenolone, progesterone, or ll-deoxycorticosterone (DOC) are readily converted to the corresponding 17-hydroxylated compounds: 17a-hydroxyprogesterone, and ll-deoxycortisol, respectively (Sandor et al., 1966, 1967). Despite exhaustive searches for
aldosterone this compound appears to be absent in this species.
Pregnenolone or progesterone have been shown to be transformed to
cortisol and/or cortisone in head kidney incubates of Fundulus heteroclitus (Phillips and Mulrow, 1959a), Mugil cephulus, Tilapia mossambica,
Amploma fibria (Nandi and Bern, 1960, 1965), and Conger conger
(Butler, 1965). It has been claimed that aldosterone is also produced in
Fundulus heteroclitus (Phillips and Mulrow, 1959a). Recently, 18hydroxylation has been suggested in the rainbow trout ( Arai and Tamaoki,
1967) and both 18-hydroxycorticosterone and aldosterone identified in
head kidney incubates of the herring, Clupea hurengus hurengus (Truscott and Idler, 1968a ) .
In elasmobranch fish, earlier claims that cortisol is present in plasma
(Phillips, 1959; Chester Jones and Phillips, 1960) and that cortisol and
aldosterone are produced in vitro by the ratfish, Hydrolagus colliei, the
329
precursors such as acetate, cholesterol, pregnenolone, or progesterone.
After a period of time the incubation medium is analyzed for steroids
formed from the precursors, and the conversion pattern of the known
steroid precursors to adrenocorticosteroids may be constructed (see
Hechter and Pincus, 1954; Dorfman, 1962).
Of the 23,OOO species of fishes, only a few have been used in such
steroid biogenetic studies. In elasmobranch fish, the adrenal gland is
homogeneous and well defined, but in all other species it has not yet been
possible to isolate the gland free from other tissue contaminants (head
kidney, connective tissue, and renal tissue). Nevertheless, in vitro incubation studies have yielded valuable information, which often correlates
with the steroid pattern present in plasma. Fish tissue usually contains
sufficient quantities of adrenocortical tissue to convert pregnenolone or
progesterone to adrenocorticosteroids in vitro. The biosynthetic pathways
and the final products obtained may differ from species to species and
from class to class.
Cardinal veins, containing the adrenocortical tissue of the eel, Anguillu
angzcilk, readily converted labeled progesterone and pregnenolone to
cortisol and cortisone (Butler, 1965; Sandor et d., 1966; Leloup-Hatey,
1966). In homogenates of the same tissues cholesterol has also been used
as a precursor for the adrenocorticosteroids of the eel (Sandor et al.,
1967). ll-Deoxycortisol was also isolated from this latter preparation.
Whether corticosterone is present as an intermediate in adrenmrticosteroid biosynthesis in the eel is in doubt. In this species, 17-hydroxylation
is very efficient. Added pregnenolone, progesterone, or ll-deoxycorticosterone (DOC) are readily converted to the corresponding 17-hydroxylated compounds: 17a-hydroxyprogesterone, and ll-deoxycortisol, respectively (Sandor et al., 1966, 1967). Despite exhaustive searches for
aldosterone this compound appears to be absent in this species.
Pregnenolone or progesterone have been shown to be transformed to
cortisol and/or cortisone in head kidney incubates of Fundulus heteroclitus (Phillips and Mulrow, 1959a), Mugil cephulus, Tilapia mossambica,
Amploma fibria (Nandi and Bern, 1960, 1965), and Conger conger
(Butler, 1965). It has been claimed that aldosterone is also produced in
Fundulus heteroclitus (Phillips and Mulrow, 1959a). Recently, 18hydroxylation has been suggested in the rainbow trout ( Arai and Tamaoki,
1967) and both 18-hydroxycorticosterone and aldosterone identified in
head kidney incubates of the herring, Clupea hurengus hurengus (Truscott and Idler, 1968a ) .
In elasmobranch fish, earlier claims that cortisol is present in plasma
(Phillips, 1959; Chester Jones and Phillips, 1960) and that cortisol and
aldosterone are produced in vitro by the ratfish, Hydrolagus colliei, the