Vol. 64, No. 1,1975
BIOCHEMICAL
AND BIOPHYSICAL RESEARCH COMMUNICATIONS
IMPAIRED REGULATION OF CORTICOSTERONE LEVELS DURING FASTING IN AGING RATS Gary W. Britton', Fels
Received
Samuel
Rotenberg',
and Richard
C. Adelman3
Research Institute and Department of Biochemistry Temple University School of Medicine Philadelphia, Pennsylvania 19140
March
lo,1975
SUMMARY: The concentration of corticosterone in aorta1 blood of 3-day fasted rats decreases approximately 75% between 2- and 24-months of age. The reduced level of hormone in aging rats is not attributable to an enhanced rate of corticosterone utilization from the blood or to a diminished steroidogenic capacity of the adrenal cortex, but apparently reflects a deficiency in extraadrenal regulatory mechanisms.
The adaptive tration
of glucose
Dawley this
rats
is
is
with
adaptation,
e.g.,
rats(4,5).
The present
that
lead
in the to this
I
regulation manifestation
indicates
response
of the
which
are
circulating
that,
of glucokinase level
adminis-
as male
Sprague-
the
increase
in
is not
impaired
during
as other
a deficiency
Therefore,
and corticosterone, report
to an altered
as well that
to the liver.
insulin
of onset
insulin
This,
factors
following
In contrast,
the possibility
of hormonal
activity
in time
to exogenous
of the lifespan(l).
be intrinsic
the availability
progressively
in response
consistent
may not
glucokinase
2- to 24-months(1,2).
enzyme activity
(3-7),
in hepatic
delayed
age from
the same portion
tion
increase
it
similar
in enzyme regula-
was suggested
crucial
results
that
to the
glucokinase
may be diminished
in older
under
experimental
activity(l),
of corticosterone
conditions
a modification may contribute
of aging.
Supported in part by Training Grant CA-05280 and Postdoctoral HD-00412 from the NIH. 2 Supported by Training Grant CA-05280 from the NIH; current Sci., Drexel Univ., Phila., PA. Dept. of Biol. 3 To whom correspondence should be sent.
Fellowship address-
BlOCHEMlCAL
Vol. 64, No. 1,1975
AND BIOPHYSICAL
RESEARCH COMMUNICATIONS
EXPERIMENTAL Animals-
Intact,
at 2-, for
male
12- and 24-months
R.C.
Adelman
at the
caesarian-derived mental
in
(6 a.m.
of age from Charles
conditions,
separate
maintained
conditioned
of the Sprague-Dawley
River
Breeding
as will
Prior
diet
reported
were
housed
were
frequented
and dark;
singly
under
by caretaker
with
and life-
these
rats
conditions: 12-hr
following
in air-
periods
sterilized
of light
Charles
and component
only
environ-
pathology
River
source;
to experimentation;
personnel
were
controlled
the following
composition
maintained The rats
rigorously
alternating
24 hr prior
colony
Laboratories.
fed a pasteurized,
at least
obtained
to experimentation
72'P.;
to be of constant
were rat
be described
publications.
at approximately
to 6 p.m.)
aging
under
in our own facility
rooms
strain
a special
and barrier-maintained
and genetic
span data were
rats
all
and rat appropriate
rats rooms
experi-
mentation. Treatments10:00
a.m.,
after
Bilateral ether
All
which
free
access
were
injected
laboratory,
National Blood
by inserting initial
corticosterone
in
of Kitabchi standard.
and possible was ruled samples injection
with per were
exposure
5 units
collected
collected
from
treated
of porcine
rats
into
to ether
in
the aorta
layer
a.m. except
chromatographic
the portal
standard(9). 185
vein
noted 3
The conoentration according
corticosterone
procedure
where
approximately
of to the
(SchwarzpMann)
of corticosterone
the assay
allowed
ACTR (20 units/ml
fluorometrically, using
were
Rats
a.m.,
anesthesia.
with
of tap water.
at 10:00
at 10:00
directly
to tap water.
anesthetization
1OOg body weight
and quantitation
out by means of thin
of corticosterone
following
access
of 1% NaCl in place
and Kitchell(8),
with
at approximately
free
surgically
serum was determined
interference
initiated
allowed
performed which
a needle
Identity
of blood
were
were
solution
Drug)
samples
min following
a
after
subcutaneously
Assay-
as
rats
were
to an aqueous
0.5% phenol;
otherwise,
of fasting
time
adrenalectomies in our
method
periods
were
by fluorescing analysis following
confirmed, metabolites
of serum
intraperitoneal
Vol. 64, No. 1,1975
BIOCHEMICAL
AND BIOPHYSICAL RESEARCH COMMUNICATIONS
RESULTS The concentrations from
the aortas
IA.
As rats
mately IA,
in
of 3-day
age from
75% from
injection
blood
fasted
42 to 9 ug per
of corticosterone
the 3-day
fasted
level
rats
in serum of blood of different
2- to 24-months,
of ACTH to 3-day
level
decreased
of corticosterone
2-month
this
of corticosterone
12-month
rats
not
Regulation
Condition A.
3-day
B.
time after of fasting
and ACTH
level
old
rats
value
shown in Table decreases
As also
approxi-
indicated
in Table
increases than
with
was quite
that
ACTH. evident
the
aorta1
observed
Since
the
at 12-months
of
I
of Corticosterone
Levels
during
Fasting
Corticosterone (ug/lOOml
Age (months)
fasted
3-day fasted treated with
treated
already
Table Age-Dependent
hormone
to an even higher old
ages are
100 ml of serum. fasted
collected
Concentration serum)
2 12 24
42 I! 3 (23) 14 ? 2 (23) 9 I! 1 (6)
12
67 + 3 (6)
2 12 2 12 2 12 2 12
60 76 28 39 41 30 24 7
adrenalectomy rats: 0 3 hours 1 day 2 days
2 ? f 2 2 -i ? ri
3 4 3 3 4 2 2 1
(6) (6) (5) (6) (6) (6) (6) (6)
A) Fasting conditions, ACTH treatment and the corticosterone assay procedure ACTH-treated rats were sampled are described in the EXPERIMENTAL section. B) Following a 24-hr fast beginning 40 min following injection at 10:00 a.m. at 1O:OO a.m., 2- and 12-month old rats were anesthetized with ether for 40 respectively, in order to elevate the endogenous circulating and 50 min., level of corticosterone. Rats then were adrenalectomized bilaterally and maintained on aqueous 1% NaCl without food for the duration of the experiment. At the indicated times following adrenalectomy, hormone levels were measured in aorta1 blood, as described in the EXPERIMENTAL section. Days 0, 1 and 2 after adrenalectomy correspond to days 1, 2 and 3 fasting. Each value represents in parentheses.
the mean f standard
186
error
for
the number
of rats
indicated
BIOCHEMICAL
Vol. 64, No. 1, ‘1975
age,
only
these
exceedingly
were
more expensive
the rate older
animals
treated
with
2-year
of corticosterone
rats,
AND BIOPHYSICAL
old
the differences
are
ACTH in order
rats.
utilization small,
RESEARCH COMMUNICATIONS
to conserve
Although
fasting
the
may increase
from blood
to a greater
as indicated
in Table
extent
in
IB.
DISCUSSION Unstimulated 24-months
circulating
are approximately
mental
conditions
amount
of corticosterone
as rats
ability
age are
This
following
administration increasing
enzyme adaptation
in rats
aged
the progressively
reduced
ability
cnncentration
12-months,
and not
at all
be ascribed
in older
fasted
rats(Table
levels
probably
of hormone
production.
to regulation
in response aging
rats
of the
2-,
of starvation
not
of hepatic
related
prob-
to growth
in 3-day required
fasted
is
rats
i.e.,
impair-
in fasted
glucokinase
12- and 24-months of 3-day
same
of corticosterone
enzymes
in the time
the
to age-associated
was observed
impairment
cannot
day fasted
is
the
rats.
activity
fasted
rats(l).
to initiate
this
accompanied
by
to increase
the
cir-
400% at 2-months,
50% at
of corticosterone
levels
at 24-months.
probably
tex --in vivo
that
environ-
100%(g).
levels
importance
of corticosterone;
The age-dependent
costerone
of aging,
delay
than
to the stress
adaptation
The progressively
culating
circulating
of glucose
remains
less
of glucocorticoid-sensitive
the age-dependent
aged 2- to
Furthermore,
serum proteins
subjected
lesion
above(9,lO).
slightly
may be of extreme
in the regulation
For example,
only
to increase
a specific
or obasity(9).
trol
with
in rats
100 ml of serum under
described
associated
of increasing
represents
ments
to those
age from 2- to 24-months,
when rats
of corticosterone
5 to 10 pg per
similar
The impaired
ably
levels
in regulation
to an enhanced IB), is
rate
Therefore,
the inability
the consequence The steroidogenic
to exogenous (Table
availability
IA).
of hormone
and/or
187
to increase
of an alteration capacity
ACTH probably Therefore,
utilization
the
is aging
effectiveness
corti-
in the con-
of the adrenal not
impaired
lesion
in
cor3-
may relate
of endogenous
ACTH.
Vol. 64, No. 1,1975
A previous
report
responsiveness ting
pool
reported rats
BIOCHEMICAL
of hypoadrenalism to exogenous
of inactive increase
is
nearly
remains
(15),
changes
levels
either
Furthermore, during
activity that
starvation
differently
rhythms
of a circula-
of young
The conceivable
of thyroid
of thyroxine
action(l4)
suggestion
may be of importance
at different
the
circadian
ages also
adult
importance
or action
of the recent
modulates
adrenal
a previously
fasting
of an inhibitor in view
by adequate
consequence
in the availability
Finally,
of circadian
levels
apparent
ACTH(ll).
the accumulation
the possibility
the
accompanied
by thyroidectomy(l2).
to be determined.
corticosterone
ACTH is
endogenous
abolished
or in
modification
--in vivo
in corticosterone
of age-dependent hormone(l3)
AND BIOPHYSICAL RESEARCH COMMUNICATIONS
that
to aging rhythm
warrants
of
examination.
ACKNOWLEDGEMENTS We are grateful for the excellent technical assistance Karoly and the research grants H&05874, H&04382, CA-12227 from the NIH and IN-88-D from the Amer. Can. SOC.
of Miss Karen and RR-05417
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.
10. 11. 12. 13. 14. 15.
Adelman, R.C. (1970) J. Biol. Chem. 245, 1032-1035. Adelman, R.C. (1970) Nature 228, 1095-1096. Finch, C.E., Foster, J.R., and Mirsky, A.E. (1969) J. Gen. Physiol. 56, 690-712. Adelman, R.C., and Freeman, C. (1972) Endocrinol. 90, 1551-1560. Adelman, R.C., Freeman, C., and Cohen, B.S. (1972) in "Advances in Enzyme Regulation", ed. by G. Weber, Vol. 10, pp. 365-382, Pergamon Press, Oxford and New York. Adelman, R.C. (1975) in "Enzyme Induction", ed. by D.V. Parke, Plenum Press Ltd., London, in press. Adelman, R.C. (1975) Fed. Proc. 2, 1797182. Kitabchi, A.E., and Kitchell, L.C. (1970) Anal. Biochem. 36, 529-537. Britton, G.W., Rotenberg, S., Freeman, C., Britton, V.J., Karoly, K., Ceci, L., Klug, T.L., Lacko, A.G., and Adelman, R.C. (1975) in "Perspectives in Aging Research", ed. by V.J. Cristofalo, R.C. Adelman and J. Roberts, Plenum Press, in press. G.D. (1970) J. Gerontol. 2, 354-358. Hess, G.D., and Riegle, Kreiger, D.T. (1974) J. Clin. Endocrinol. Metab. 38, 964-975. Hainer, V., Kubik, V., and Stoilov, S. (1972) Hormone and Metab. Res. 4, 314-315. N.V., and Valueva, G.V. (1973) Exper. Frolkis, V.V., Verzhikovskaya, Geront. 8, 285-296. Denckla, W.D. (1974) J. Clin. Invest. 2, 572-581. Pittendrigh, C.S., and Daan, S. (1974) Science 186, 548-550.
188