Tryptophan uptake and tryptophan oxygenase activity in mice

Vol. 41, No. 6, 1970

BIOCHEMICAL

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

TRYPTOPHANUPTAKEANDTRYPTOPHANOXYGENASE ACTIVITY

Ralph

P.

November

SUMMARY:

Groups

of

1 mg/gm

temperature heat-stressed

(ZZOC) or animals,

levels

were

preexposed plasma

not

levels

but

as

a result

and

tryptophan

oxygenase

INTRODUCTION:

The

numerous

induce

We

combined

exposure this

to

amino

elicits flow

amino

acid

viscera

few

have

substrate

evaluate

the Since

acid.

skeletal

hepatic

has

effects

in

uptake, of (4-6)

(l-3).

Although

tryptophan

upon

effects

of tryptophan

muscles

extensively oxygenase

of

the

concentration

exposure

been

oxidoreductase)

examined

vascular

tryptophan

tryptophan

inducing

vasodilation and

Hence, acute uptake of the amino

unaffected.

enzyme

the

controls; activity

In mice which had been tryptophan administration, yet hepatic substrate

tryptophan

oxygen

In the at each

temperature oxygenase

induction, are

room

stress (36°C). levels were lower

unaffected. vascular

enzyme

administration

a peripheral to

were reduces

catabolizing

upon

to

with at

with room tryptophan

and

activity

describe

activity

have

Medicine

intraperitoneally maintained heat

prior further,

rapid

oxygenase,

enzyme

hour activity heat

of

its

reports

and

to acute tryptophan

L-tryptophan:

tryptophan

Mager

01760

injected

different.

acid,

1.13.1.12,

weight,

for one decreased

and enzyme environmental

(EC

were

body

significantly heat were

to

to

mice

when compared tryptophan

concentration exposure

utilized

Massachusetts

exposed plasma

studied hepatic

to

Milton

9, 1970

L-tryptophan,

time interval however, both

and

and Pharmacology Laboratory Institute of Environmental

Natick,

Received

MICE

Francesconi

Biochemistry Army Research

U. S.

IN

of the

the

plasma

or

with

acute

heat

delivery,

rats

to

high

1494

this

and

with shift

liver.

catabolism

ambient

combined (7),

increased

temperatures a decreased

in

of

blood

supply

blood

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Vol. 4 1, No. 6, 1970

affords

a supplementary

this

amino

Adult,

Laboratories,

of

to use

f 1°C

with

injected and at

in

and

liver

30,

60,

been

and

and

aspirated

off,

resulting oxygenase

were

and

the its

and

from

to

at

both

36

groups

exactly

were

performed

on

hour

before

and

exposed

to

heat

were

obtained

30 minutes

for

tryptophan.

hours

to

circadian

tryptophan 70,

80,

and

puncture, by

and

centrifugation, All

delete

periodicities

substrate

administration.

of

cardiac

assayed 1200

which

after

a total

by

10,

animals

substrate

for

acute

f 1°C.

administration.

until

any

animals effects

of hepatic

tryptophan

(8).

Chemical

tryptophan

remained

tryptophan

one

and

animals

maintained

20

1000

L-tryptophan,

subjected

separated

liver

ratio

Co.,

St.

with

6N

Louis,

MO.)

NaOH,

concentrations to the

fluorometer

excitation

Hepatic

by

and

Jervell

is

expressed

of

the

liver

procedure (11).

wet

as

method and

and

respectively. by

gram

were

was

alkalinization

measured

per

the

were

after

10,

according

provided

oxygenase

half

animals

and

was

then

dissolved

adjusted

to

HCl.

a Farrand

Seglen

for

by

fluorometrically,

nm

other

obtained

circulating

water

Plasma

which

of

one

temperature

of

plasma

(Sigma

with

Half

natural

L-tryptophan

8.0

groups. the

at least

The

tubes; frozen

between

water.

two

samples

heparinized

or

pH

of

Breeding

ambient

weight

heat

hence,

an

body

minutes

sacrificed

from

distilled

240

for

1 mg/gm

were

to

and

at

chamber

were

sacrificed

in

disposition

River

with

experiments

Blood in

were

and

housed

cages

food

environmental samples

animals

collected

460

to

into

preexposed

minutes.

with

access

several

injection,

90

uptake

Charles

were

steel

while

an

120,

addition,

These

the

(HAM-ICR,

stainless

conditions,

stress

Blood

study

Mass.)

divided

ambient

had

mice

intraperitoneally

heat

In

in free

randomly

20,

male

Wilmington,

prior 22

to

acid.

METHODS:

week

means

of

filters

emission

Knox

In

our

and

Dewey

CS

and

CS

7-51 of

oxygenase and

study

micromoles

Auerbach specific of

weight.

1495

determined

Denckla

wavelengths

tryptophan of

were

kynurenine

365

(10) activity

as

4-76

nm

activity

(9),

and was

modified of tryptophan

formed

per hour

Vol. 41, No. 6,197O

BIOCHEMICAL

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

I 0

10

30

Figure

1.

The

effect

plasma injection (no

of

both 22C triplicate dotted

Figure

following The

samples represents

The

the 4 animals

results

exposed (dotted

acute

line)

the

of the

triplicate

heat plasma

to

heat

of

plasma acid

the

nearly

Each the

of stress. levels

circulating

time

the

animals

of

tryptophan

and

the

of

to four

other

points

blood

of in

the

preexposed

there

animals to

more

at

each

studied in

even

hour

exposure

value

interval

are

The of

tryptophan

pooled

tryptophan

In

1496

of

one

performed

every

at of

sample for

mean

determinations at

value,

a pooled

amino

in

on the

concentration of four animals.

from

animals.

& 36C)

intraperitoneal weight. Time 0 value four samples of pooled

successive

levels

concentration

concentration to

values

the

17 different

that

of

each

represents

tryptophan with

mean

had been exposed administration.

0 measurement

indicate

a decreased

the

injection

from

(22C after body

represents the mean of the pooled plasma

1 demonstrates

time pooled

while

represents

intraperitoneal

heat.

least

and 36C, analyses

line

the

17 animals,

animals which to tryptophan

RESULTS:

temperature in mice 1 mg/gm

represents

from

240

INJECl,OW

environmental

tryptophan)

120

AFTE”

levels of tryptophan of L-tryptophan,

plasma

five prior

II ”

60 MINUTES

heat markedly

case. is

Vol. 4 1, No. 6, 1970

reduced in

at 10,

tryptophan

(125-fold) acid

BIOCHEMICAL

20,

and

30

minutes.

concentration animals

under

in

indicate

either

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

The

both

heat

rapid

(10

environmental

0 I 10 2.

f S. E. M. the mean

increase tryptophan range

with

hepatic

are

compared higher

twice

levels

to in

those the

of

are

not

10 minutes

as

great

in

preexposed heat

amino

stressed

Time

values to heat

plasma

maintained

nearly

six

a reflection

animals for

one

mice.

1497

hour

values on

100 in fold.

after

a much

narrower

Secondly,

hepatic plasma

of tryptophan, room to heat,

the which

of tryptophan

of tryptophan

at

represents

other Points

levels

injection kept

0 value

on the of

from five animals for one hour.

are

after

& 36C) injection

while all 4 samples.

of approximately

increase

example,

the

of

(22C i.p.

after

weight.

whereas

of magnitude

a maximum

For

body

that,

concentrations

levels. levels

order

injection,

tryptophan

are

an

control

240

temperature in mice

the mean exposed

2 demonstrates by

120

of 17 samples; f S. E. M. of

dotted line indicate had been previously

Figure

and

AFTER INJECTION

1 mg/gm

the mean represent

(85-fold) absorption

,I 60 ”

environmental of tryptophan

L-tryptophan,

increase

condition.

30

The effect of hepatic levels

of the

stressed

minutes)

MINUTES

Figure

magnitude

plasma

temperature while

when hepatic

levels

Vol. 41, No. 6, 1970

Both

of

regulation the

BIOCHEMICAL

these

observations

of tryptophan

rapid

tryptophan

of

this

catabolic

administration. increased,

of hepatocytes

is

plasma

levels.

and

reduced,

enzyme

net

without

Again,

acute

induction

in

explained

by

tryptophan.

by

the

considering Figure

just

alteration

in

of free

after tryptophan

is

tryptophan

between

exposure

the 3 demonstrates

minutes

degradation

correlations

heat

the

be

enzyme

Thus,

concomitantly

upon

can

oxygenase

induction

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

levels

hepatic

apparently

has

and

no

effect

liver.

.-

-*

22Oc 36-z PREHEAI

4

2

Figure

The

3.

0 I,. 10

30

of

environmental

effect

induction injection

of hepatic of L-tryptophan,

240

60 120 HWWTES AFTER IN,EC,,O,,

temperature

tryptophan

(22C

oxygenase 1 mg/gm body

& 36C)

in mice weight.

on

after Time

the i. p. 0 value

represents the mean f S. E. M. of 17 samples, while all other values represent the mean f S. E. M. of 4 samples. Specific activity is in terms of umoles kynurenine formed per hour per gram liver wet weight. Points on the dotted line represent mean values from animals which had been preexposed to heat for

one

DISCUSSION:

hour.

Increases

result

of

ideal

system

in

intraperitoneal to

study

liver

tryptophan

administration the

relationship

oxygenase of tryptophan

between

1498

substrate

activity make

as this

uptake

an and

a

Vol.41,No.6,

enzyme

induction.

tryptophan but

BIOCHEMICAL

1970

It has

oxygenase

rather

by

formation in

control

animals

synthesis

of

at

decreases

further

most

flow this

liver.

to

the

effect

accelerates

hepatic

concentrations

in

However, tryptophan are

no

uptake this and

the

and

catabolism

the

rapid and

protein

in

this

with

is

an

of

sites

of

in free

acute

of

liver

heat

intraperitoneally

hour

to

heat

by

a decrease How-

induction

in

no the

oxygenase thus

stress

blood

has

compared

the

of

tryptophan

maintaining to plasma

will

levels.

probably compound.

inductive

of tryptophan acute

one

actually

administered

nature

animals

absorption.

enzyme

when

due

in

tryptophan.

for

tryptophan,

constant

instance,

lower

flow

substrate or

catabolism

of

increased

the

increase

of

for

compensated

the

effects

levels

to heat

availability

to

consistently

administered

absorption

catabolic net

the

for

compared

particularly

specific

significant

disposition

an

allowing

heat-stressed

results

dissipation,

exposure

of

enzyme,

Hence,

both

stress

for

that

then,

thus

intraperitoneally

relatively

general, the

of

substrate

the

hematin

Preexposure

heat

indicate

of

mechanisms

when

viscera,

on

activity

reduce

heat

peritoneal

Results

In

for

synthesis

(12). in

induces

involved.

explanation

reduced

significant

since

uptake

tissues

of blood

unexpected

temperature.

plausible

novo with

activity

not

tryptophan

holoenzyme

tryptophan

the

--de

apoenzyme

to acute

room

peripheral

ever,

mice

circulating

maintained

to

not

that

oxygenase

are

of

by

reduced

apparently

values

The

active,

is

not the

tryptophan

Exposure

postulated

activity

conjugating

of the

increase

been

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

nature

of

oxygenase,

exposure

on

there the

overall

tryptophan.

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