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

Impaired regulation of corticosterone levels during fasting in aging rats.

Vol. 64, No. 1,1975 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS IMPAIRED REGULATION OF CORTICOSTERONE LEVELS DURING FASTING IN AGING RATS G...
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