348
CHESTER JONES, CHAN, HENDERSON, AND BALL
livers heavier than those of controls but with the same glycogen content.
They did, however, find that ACTH prevented the net glycogen synthesis
that normally followed the injection of glucose into fasted fish, and that
this was probably brought about by the ACTH enhancing glycogenolysis,
since it did not block the incorporation of radioactive glucose into liver
glycogen. Thus in Tilapia, as in Poecilia, we have indications that ACTH
and cortisol may enhance glycogenolysis and that this action in these
species outweighs any accompanying stimulation of gluconeogenesis. It
is interesting to note that data from amphibians suggest a pituitary stimulation of glycogenolysis, possibly via pituitary potentiation of the glycogenolytic action of adrenaline (Houssay et al., 1937; Kepinov, 1947); the
fish data suggest that in this group the “hormone glycog¬rope”
(Kepinov) may be ACTH, and that its promotion of glycogenolysis is
relatively more important in some fish (TiZupia and Poecilia) than in
others such as the eel ( Hatey, 1951a,b).
E. Effects on Blood Cells
Hypophysectomy leads to a fall in the numbers of circulating red
blood cells (RBC), white blood cells ( WBC), and thrombocytes (TC) in
Fundulus heteroclitus ( Slicher, 1961), Poecilia formosa (Ball at al., 1965),
and P. latipinnu (Ball et al., 1966b). Chronic treatment with ACTH
maintained RBC and WBC in hypophysectomized F . heteroclitus
(Slicher, 196l), and ACTH also maintained RBC, WBC, and TC in
hypophysectomized 2’. latipinnu (Ball et al., 1966b). Cortisol also maintains WBC in hypophysectomized P. latipinnu (Ball, 1968). These data
suggest that ACTH and cortisol may be physiologically involved in hematopoiesis, but this is not firmly established since other hormones can
maintain some or all of these parameters in hypophysectomized P. Zatipinna (TSH, thyroxine, growth hormone, and prolactin: Ball et al.,
1966b; Ball, 1968) and hypophysectomized F . heteroclitus (TSH and/or
LH, testosterone, possibly prolactin; Slicher, 1961 ) . However, support for
the possibility of the physiological maintenance of WBC by ll-oxycorticosteroids comes from the fall in WBC in intact P. Zutipinnu treated with
metopirone (Ball et al., 1966b).
ACTH and cortisol are probably physiologically concerned in the
short-term response of WBC to stress. Cold stress in F . heteroclitus and
P. latipinnu elicits characteristic changes, an initial leukopenia followed
by leukocytosis, within 2 or 4 hr (Slicher et al., 1962; Ball and Slicher,
1962). The second phase (leukocytosis) is abolished by hypophysectomy
in both species and by metopirone in P . latipinnu, but the first phase
CHESTER JONES, CHAN, HENDERSON, AND BALL
livers heavier than those of controls but with the same glycogen content.
They did, however, find that ACTH prevented the net glycogen synthesis
that normally followed the injection of glucose into fasted fish, and that
this was probably brought about by the ACTH enhancing glycogenolysis,
since it did not block the incorporation of radioactive glucose into liver
glycogen. Thus in Tilapia, as in Poecilia, we have indications that ACTH
and cortisol may enhance glycogenolysis and that this action in these
species outweighs any accompanying stimulation of gluconeogenesis. It
is interesting to note that data from amphibians suggest a pituitary stimulation of glycogenolysis, possibly via pituitary potentiation of the glycogenolytic action of adrenaline (Houssay et al., 1937; Kepinov, 1947); the
fish data suggest that in this group the “hormone glycog¬rope”
(Kepinov) may be ACTH, and that its promotion of glycogenolysis is
relatively more important in some fish (TiZupia and Poecilia) than in
others such as the eel ( Hatey, 1951a,b).
E. Effects on Blood Cells
Hypophysectomy leads to a fall in the numbers of circulating red
blood cells (RBC), white blood cells ( WBC), and thrombocytes (TC) in
Fundulus heteroclitus ( Slicher, 1961), Poecilia formosa (Ball at al., 1965),
and P. latipinnu (Ball et al., 1966b). Chronic treatment with ACTH
maintained RBC and WBC in hypophysectomized F . heteroclitus
(Slicher, 196l), and ACTH also maintained RBC, WBC, and TC in
hypophysectomized 2’. latipinnu (Ball et al., 1966b). Cortisol also maintains WBC in hypophysectomized P. latipinnu (Ball, 1968). These data
suggest that ACTH and cortisol may be physiologically involved in hematopoiesis, but this is not firmly established since other hormones can
maintain some or all of these parameters in hypophysectomized P. Zatipinna (TSH, thyroxine, growth hormone, and prolactin: Ball et al.,
1966b; Ball, 1968) and hypophysectomized F . heteroclitus (TSH and/or
LH, testosterone, possibly prolactin; Slicher, 1961 ) . However, support for
the possibility of the physiological maintenance of WBC by ll-oxycorticosteroids comes from the fall in WBC in intact P. Zutipinnu treated with
metopirone (Ball et al., 1966b).
ACTH and cortisol are probably physiologically concerned in the
short-term response of WBC to stress. Cold stress in F . heteroclitus and
P. latipinnu elicits characteristic changes, an initial leukopenia followed
by leukocytosis, within 2 or 4 hr (Slicher et al., 1962; Ball and Slicher,
1962). The second phase (leukocytosis) is abolished by hypophysectomy
in both species and by metopirone in P . latipinnu, but the first phase