Adrenalectomy or interrenalectomy in non-mammalian vertebrates is often a
difficult procedure, and the changes observed in different species are inconsistent
(CHESTER JONES, 1957). Birds, reptiles and amphibians die after removal of the
adrenals, but some species , like the frog Rana temporaria, may survive for several
months if the operation is performed in winter, or die in two or three days if it
is done in summer. Sharks and rays (Chondrichthyes) survive about one to three
weeks after interrenalectomy (see HARTMAN et al., 1944). CHAN et al. (1967a) have
performed this formidable operation in eels (Osteichthyes), and their animals survived for at least three or four weeks. The metabolic condition and environmental
situation of animals, especially poikilotherrns, appears to influence their survival
following adrenalectomy.
In non-mammalian vertebrates, the metabolic changes associated with adrenalectomy or interrenalectomy may be simil ar to those in mammals, or sometimes
vary from this pattern. HARTMAN et al. (1944) found that interrenalectomy in the
skate, resulted in a decreased blood glucose and liver glycogen, but no detectable
changes in sodium and potassium metabolism. Adrenalectomy in the desert lizard,
Tracbysaurus rugosus, produces an elevated plasma potassium level but no change
in sodium (BENTLEY, 1959b). Removal of the adrenocortical tissue of the eel does
not affect plasma potassium levels, but results in a decreased plasma sodium in fish
kept in fresh water, and elevated sodium if the animals are in sea-water (CHAN et
al., 1967a). It thus appears that the effects of adrenalectomy on electrolyte metabolism are at least partly related to the osmotic situation and relative availability
of sodium and potassium and the physiological need for conservation or excretion
of these ions .
The three principal adrenocortical steroids (corticosteroids) produced by vertebrates are cortisol, corticosterone and aldosterone. In addition, small amounts
of androgens and oestrogens may be secreted by this tissue. The distribution of
the three major steroids varies in different vertebrates. Cortisol and corticosterone
are present in species throughout the vertebrate series, but their presence and relative abundance varies greatly. Thus the ratios in the plasma levels of cortisol/corticosterone varies from 0.05 in rats , to 4 in the cat and 20 in a monkey,
Macaca mulatta (BUSH 1953). Aldosterone is widespread among the tetrapods, but
rare or absent in the fishes.
The natural and synthetic adrenocortical steroids are, for convenience, often
classified into two main groups. 1. Mineralocorticoids, which have prominent effects on sodium and potassium metabolism . Aldosterone and deoxycorticosterone
are the main natural examples of this, while fluorocortisol is a potent synthetic analogue. 2. Glucocorticoids, which have more pronounced actions with respect to the
interconversions among carbohydrates, fats and proteins. These include cortisol
and corticosterone and synthetic analogues like prednisone and betamethasone.
It should be remembered that the dividing line between these groups is not a clear
one, and that there may be considerable crossover in their respective activities. Cortisol and corticosterone also exhibit effects on electrolyte metabolism, while on
a purely molecular basis, aldosterone exhibits considerable glucocorticoid activity.
The ratios of the two major activities vary, the mineralo/gluco-corticoid activity
(measured in mammals) is: aldosterone, 100; corticosterone, 0.015; and for cortisol,
0.01; a 10 thousand-fold range.
75
difficult procedure, and the changes observed in different species are inconsistent
(CHESTER JONES, 1957). Birds, reptiles and amphibians die after removal of the
adrenals, but some species , like the frog Rana temporaria, may survive for several
months if the operation is performed in winter, or die in two or three days if it
is done in summer. Sharks and rays (Chondrichthyes) survive about one to three
weeks after interrenalectomy (see HARTMAN et al., 1944). CHAN et al. (1967a) have
performed this formidable operation in eels (Osteichthyes), and their animals survived for at least three or four weeks. The metabolic condition and environmental
situation of animals, especially poikilotherrns, appears to influence their survival
following adrenalectomy.
In non-mammalian vertebrates, the metabolic changes associated with adrenalectomy or interrenalectomy may be simil ar to those in mammals, or sometimes
vary from this pattern. HARTMAN et al. (1944) found that interrenalectomy in the
skate, resulted in a decreased blood glucose and liver glycogen, but no detectable
changes in sodium and potassium metabolism. Adrenalectomy in the desert lizard,
Tracbysaurus rugosus, produces an elevated plasma potassium level but no change
in sodium (BENTLEY, 1959b). Removal of the adrenocortical tissue of the eel does
not affect plasma potassium levels, but results in a decreased plasma sodium in fish
kept in fresh water, and elevated sodium if the animals are in sea-water (CHAN et
al., 1967a). It thus appears that the effects of adrenalectomy on electrolyte metabolism are at least partly related to the osmotic situation and relative availability
of sodium and potassium and the physiological need for conservation or excretion
of these ions .
The three principal adrenocortical steroids (corticosteroids) produced by vertebrates are cortisol, corticosterone and aldosterone. In addition, small amounts
of androgens and oestrogens may be secreted by this tissue. The distribution of
the three major steroids varies in different vertebrates. Cortisol and corticosterone
are present in species throughout the vertebrate series, but their presence and relative abundance varies greatly. Thus the ratios in the plasma levels of cortisol/corticosterone varies from 0.05 in rats , to 4 in the cat and 20 in a monkey,
Macaca mulatta (BUSH 1953). Aldosterone is widespread among the tetrapods, but
rare or absent in the fishes.
The natural and synthetic adrenocortical steroids are, for convenience, often
classified into two main groups. 1. Mineralocorticoids, which have prominent effects on sodium and potassium metabolism . Aldosterone and deoxycorticosterone
are the main natural examples of this, while fluorocortisol is a potent synthetic analogue. 2. Glucocorticoids, which have more pronounced actions with respect to the
interconversions among carbohydrates, fats and proteins. These include cortisol
and corticosterone and synthetic analogues like prednisone and betamethasone.
It should be remembered that the dividing line between these groups is not a clear
one, and that there may be considerable crossover in their respective activities. Cortisol and corticosterone also exhibit effects on electrolyte metabolism, while on
a purely molecular basis, aldosterone exhibits considerable glucocorticoid activity.
The ratios of the two major activities vary, the mineralo/gluco-corticoid activity
(measured in mammals) is: aldosterone, 100; corticosterone, 0.015; and for cortisol,
0.01; a 10 thousand-fold range.
75