180
JAMES K. GRANT
observation might possibly be related to changes in metabolism of the
fish in preparation for entering a more saline medium. Cortisol has also
been tentatively identified in the plasma of carp by paper chromatography. It was estimated that plasma of the male fish contained 24 ^g.
"hydrocortisone" per 100 ml. and that the female contained twice as
much (79).
Thus there are a few suggestions that fish may elaborate adrenocortical steroids, but good evidence for this is not available at present.
Similar evidence based largely on the observed effect of hypophysectomy or adrenalectomy is available for amphibians, reptiles, and
birds, but facts on the nature of the adrenocortical secretion are lacking
(74). Grant and Griffiths (unpublished results) have shown that the
adrenals of the domestic fowl possess enzymes that catalyze hydroxylation of progesterone and DOC at the 11-, 17-, and 21-positions.
The hypothesis has been advanced that the prime necessity for the
evolution of vertebrates was ionic regulation at the kidney level, possibly by adrenocortical hormones. Vital processes are frequently found
to be regulated by two opposing factors, for example, the control of
blood sugar by glucagon and insulin. It would therefore not be surprising to find that ionic regulation is achieved by two factors: aldosterone promoting sodium retention, and a hitherto unknown factor
promoting sodium excretion. There is indirect evidence for the functioning of such a factor in human subjects with certain types of adrenal
tumors who have a craving for salt, and strong support for this idea
has recently been obtained with the isolation of 3/?,16«-dihydroxy-5apregnan-20-one from hog adrenals (80).* This substance promotes sodium excretion in the rat. Its structure is unlike the known neutral
steroid hormones, which possess the Δ
4
-3-οχο grouping, and suggests
the possibility that an even more active "sodium excreting" steroid
remains to be discovered. The 16a-hydroxyallopregnanolone has not so
far been found in the adrenal secretion and thus cannot be described
as a hormone.
3. Biosynthesis of Steroid Sex Hormones
a. Introduction. Apart from information on occurrence in tissues
and body fluids of those steroids which influence reproductive organs,
little is known about the comparative aspects of the biogenesis of the
so-called steroid sex hormones.
The biosynthesis of these substances is not confined to the gonads
but may also take place in the adrenal cortex and placenta.
* The authors have been unable to confirm this observation.
JAMES K. GRANT
observation might possibly be related to changes in metabolism of the
fish in preparation for entering a more saline medium. Cortisol has also
been tentatively identified in the plasma of carp by paper chromatography. It was estimated that plasma of the male fish contained 24 ^g.
"hydrocortisone" per 100 ml. and that the female contained twice as
much (79).
Thus there are a few suggestions that fish may elaborate adrenocortical steroids, but good evidence for this is not available at present.
Similar evidence based largely on the observed effect of hypophysectomy or adrenalectomy is available for amphibians, reptiles, and
birds, but facts on the nature of the adrenocortical secretion are lacking
(74). Grant and Griffiths (unpublished results) have shown that the
adrenals of the domestic fowl possess enzymes that catalyze hydroxylation of progesterone and DOC at the 11-, 17-, and 21-positions.
The hypothesis has been advanced that the prime necessity for the
evolution of vertebrates was ionic regulation at the kidney level, possibly by adrenocortical hormones. Vital processes are frequently found
to be regulated by two opposing factors, for example, the control of
blood sugar by glucagon and insulin. It would therefore not be surprising to find that ionic regulation is achieved by two factors: aldosterone promoting sodium retention, and a hitherto unknown factor
promoting sodium excretion. There is indirect evidence for the functioning of such a factor in human subjects with certain types of adrenal
tumors who have a craving for salt, and strong support for this idea
has recently been obtained with the isolation of 3/?,16«-dihydroxy-5apregnan-20-one from hog adrenals (80).* This substance promotes sodium excretion in the rat. Its structure is unlike the known neutral
steroid hormones, which possess the Δ
4
-3-οχο grouping, and suggests
the possibility that an even more active "sodium excreting" steroid
remains to be discovered. The 16a-hydroxyallopregnanolone has not so
far been found in the adrenal secretion and thus cannot be described
as a hormone.
3. Biosynthesis of Steroid Sex Hormones
a. Introduction. Apart from information on occurrence in tissues
and body fluids of those steroids which influence reproductive organs,
little is known about the comparative aspects of the biogenesis of the
so-called steroid sex hormones.
The biosynthesis of these substances is not confined to the gonads
but may also take place in the adrenal cortex and placenta.
* The authors have been unable to confirm this observation.