PCDFs

C h e m o s p h e r e , Vol.20, Nos.7-9, Printed in Great B r i t a i n

VITAMIN

A STORAGE

pp 1147-1150,

IN RATS

SUBCHRONICALLY

H. H~kansson*, Institute

of E n v i r o n m e n t a l

U.G.

Ol

0 0 4 5 - 6 5 3 5 / 9 0 $3.00 + .00 P e r g a m o n Press plc

EXPOSED

Ahlborg,

Medicine,

S-I04

1990

TO

PCDDs/PCDFs

L. Johansson,

Karolinska

STOCKHOLM,

Instituter,

Box

60208,

Sweden.

H. Poiger Institute

Federal

of Toxicology,

Institute

ZOrich,

of T e c h n o l o g y

and U n i v e r s i t y

of

CH-8603

SCHWERZENBACH,

Switzerland.

ABSTRACT

This s t u d y d e m o n s t r a t e s that h e p a t i c v i t a m i n A r e d u c t i o n o c c u r s as a c o n c e q u e n c e of l o w - l e v e l l o n g - t e r m e x p o s u r e to 2 3 7 8 - s u b s t i t u t e d but not n o n - 2 3 7 8 - s u b s t i t u t e d congeners. The p o t e n c y of i n d i v i d u a l c o n g e n e r s to reduce h e p a t i c v i t a m i n A c o n t e n t s c o r r e l a t e d r e a s o n a b l y well w i t h their p o t e n c y to p r o d u c e s u b c h r o n i c toxicity.

to

INTRODUCTION

Similarities dietary

between

vitamin

symptoms

A deficiency

occurring

Results

from t h e s e d e m o n s t r a t e

hepatic

stores

investigate

whether

of l o w - l e v e l thereof.

of v i t a m i n

It was

individual

MATERIALS

Groups

effect

AND

hepatic

if c o - e x p o s u r e

PCDDs/PCDFs

occurs

are able

also

to several

studies.

to reduce to

as a c o n s e q u e n c e

and to m i x t u r e s

if the p o t e n c y

A stores

In addition,

and after

exposure

s t u d y was m a d e

PCDDs/PCDFs

vitamin

to v i t a m i n

exposure

single

The p r e s e n t

A reduction

toxicity.

with regard

were

of

in a c c o r d a n c e

it was an aim of the

PCDDs/PCDFs

would

result

in

A reduction.

METHODS

of 6 a p p r o x i m a t e l y

maintained

several

to i n d i v i d u a l

to r e d u c e

to p r o d u c e

to i n v e s t i g a t e

an a d d i t i v e

vitamin

exposure

several

an aim of the s t u d y to i n v e s t i g a t e

PCDDs/PCDFs

with the p o t e n c y study

that

A in rodents.

hepatic

long-term

after PCDD/PCDF

have p r o m p t e d

7 weeks

old male

Iva:

for 13 w e e k s

on d i f f e r e n t

PCDD/PCDF

libitum

in two s e p a r a t e

experiments.

Control

without

PCDD/PCDF

addition.

Chemicals

diets

animals

and diets

1147

SIV 50

(SD)

(Table

rats were i) and w a t e r

received

ad

the same diet

used w e r e p r e p a r e d

and

1148

controlled was made Tissue

as d e s c r i b e d as d e s c r i b e d

extraction

by P l u e s s

and v i t a m i n

previously

described

hydrolysed

before

high p r e s s u r e

by P l u e s s

liquid

et al (1988)

A analysis

(HAkansson

extraction

et al (1988).

and P I O s s

in t r i p l i c a t e

et al 1987),

of v i t a m i n

The t o x i c o l o g i c a l

i.e.

A, w h i c h

evaluation

et al (1988). were made

tissues

were

was a n a l y z e d

as

completely as r e t i n o l

by

chromatography.

Table i: Composition of the experimental diets, dietary PCDD/PCDF and vitamin A intake during the 13-week experimental period and the effect of PCDD/PCDF-treatmenton the hepatic vitamin A content. Dose r0up ~g/kg)

i

PCDD/PCDF conc. Estimated dietary intake of: in the diet PCDDs/PCDFs Vitamin Aa (zg per rat) (Pg per rat)

Liver vitaminA (zg)

Experiment I: 0.48 5.03 42.84

7623 7182 7539 6426

339411373 25961779r,6 i081!357a,~, 4 23!17u,~,r

2 20 200

512 44.94 413.0

7686 6741 6195

2489!483r,~ 4821150a,8,r, ~ 612a,~,r

2

4.51

6558 6762

26271547 7771279a

6228 6444

26501574r 3280!i000r

4.56 45.50 432,6

6843 6825 6489

3655±622a,r 2519!333r 9011210m

4.90 43.86 405.0

7350 6579 6075

3600±782a,r 16821254a,r 77133a,r

6663

1703!337a,r

6204

6h15 a,r

Control

2,3,7,8-TCDD

10w medium high

0.2 2 20

2,3,4,7,8-PeCDF

low medium high

Control 2,3,7,8-TCDD

medium

1,2,3,4,8-PeCDF

10w high

1,2,3,7,8-PeCDF

10w medium high

2 20 200

1,2,3,6,7,8-HxCDF

10w medium high

2 20 200

2,3,7,8-TCDD 2,3,4,7,8-PeCDF 1,2,3,6,7,8-HxCDF 1,2,3,7,8-PeCDD

Mix 10w

2,3,7,8-TCDD 2,3,4,7,8-PeCDF 1,2,3,6,7,8-HxCDF 1,2,3,7,8-PeCDD

Mix high

Experiment II:

600 6000

0.2 2 1 i 2 ZQ i0 I0

1246 12888

a The dietary vitamin A content was i0 000 IU/kg i.e. 3 mg/kg. a, 8, r, and d denotes exposed groups that are significantly different (p<0.05) from the corresponding controls and the corresponding low, medium, and high TCDD groups, respectively, when analyzed by the non parametric Wilcoxon tw0-sample test.

1149

Data r e p o r t e d are the a r i t h m e t i c m e a n s

± standard deviation.

Statistically

s i g n i f i c a n t d i f f e r e n c e s w e r e d e t e r m i n e d by the n o n - p a r a m e t r i c W i l c o x o n two-sample test significant

(Sokal and R o h l f

at the p <0.05

1981).

Comparisons were considered

level.

RESULTS

B o d y w e i g h t gain,

food consumption,

chemistry,

a n d h i s t o l o g y of a n i m a l s

previously

( P l u e s s et al 1988,

t i s s u e weights, in the p r e s e n t

PlOss et al 1988).

hematology,

blood

study have been reported Briefly,

the e x p e c t e d

toxic s y n d r o m e was o b s e r v e d w i t h the 2 3 7 8 - s u b s t i t u t e d c o n g e n e r s . estimated TCDD-equivalence the o b s e r v e d

symptoms

factors

(TEF)

for i n d i v i d u a l

congeners

The b a s e d on

are g i v e n in T a b l e 2. The s u b c h r o n i c t o x i c i t y of the

m i x t u r e s e e m e d to be in a c c o r d w i t h an a d d i t i v e e f f e c t of the i n d i v i d u a l congeners.

Table 2. E s t i m a t e d T C D D - e q u i v a l e n c y f a c t o r s (TEF) for s e v e r a l P C D D s / P C D F s based on t o x i c i t y and h e p a t i c v i t a m i n A r e d u c t i o n o b t a i n e d in 1 3 - w e e k - d i e t a r y e x p o s u r e s t u d i e s w i t h rats.

Congener

Estimated Toxicity

2378-TCDD 12348-PeCDF 12378-PeCDF 23478-PeCDF 123678-HxCDF

1 <0.0003 b 0.01 b 0.3-0.5 c 0.i b

1 <0.0003 0.01 0.25 0.02-0.05

additive

additive

Mixture b

T C D D - e q u i v a l e n c y f a c t o r s b a s e d on: Hepatic vitamin A reduction a

a A l o g - l i n r e p r e s e n t a t i o n of the p e r c e n t r e d u c t i o n of the total a m o u n t of liver v i t a m i n A c a u s e d by 2 3 7 8 - T C D D was used to e s t i m a t e the " e q u i v a l e n t T C D D - d o s e " for the i n d i v i d u a l c o n g e n e r s . This d o s e d i v i d e d by the actual d o s e g i v e n forms the e s t i m a t e d TEF. b Data from P l u e s s et al 1988. c Data from P l ~ s s et al 1988.

The e s t i m a t e d d i e t a r y i n t a k e of v i t a m i n A in e x p o s e d g r o u p s was s i m i l a r the i n t a k e in the c o r r e s p o n d i n g c o n t r o l s e x c e p t 23478-PeCDF groups

in e x p e r i m e n t

I (Table i).

for the h i g h 2 3 7 8 - T C D D

The i n t a k e was

15-20%

to and

lower

in

these g r o u p s t h a n in the controls. H e p a t i c v i t a m i n A storage.

Experiment

c o n c e n t r a t i o n of 1 6 0 ± 6 0 ~g/g,

~g (Table I) at the end of the study. similar dose-related e x p o s e d rats, Experiment

decrease

however,

I: C o n t r o l

a n i m a l s had a v i t a m i n A

c o r r e s p o n d i n g to a total Compared

in liver v i t a m i n A was

c o n c e n t r a t i o n of 155±38 ~g/g,

corresponding

rats a

found for 2 3 4 7 8 - P e C D F

at a t e n - f o l d h i g h e r d o s e - l e v e l

II: At the end of the s t u d y c o n t r o l

a m o u n t of 3 3 9 4 ± 1 3 7 3

to 2 3 7 8 - T C D D e x p o s e d

(Table i).

a n i m a l s had a v i t a m i n A

to a total

a m o u n t of 2 6 2 7 ± 5 4 7

pg

i150

(Table

i).

These

the 1 2 3 4 8 - P e C D F containing increased Groups

levels w e r e c o m p a r a b l e diet

vitamin

receiving

decreased

at e i t h e r

12378-PeCDF

these

hepatic

to 2 3 7 8 - T C D D

obtained

in the

wh i l e

the

A contents

exposed

12378-PeCDF

123678-HxCDF

this dosage.

as c o m p a r e d

Exposure

exposed

lower h e p a t i c

control

rats.

Significantly

treated

g r o u p was o b s e r v e d

control

at 200 ~ g / k g b o t h

as c o m p a r e d

showed

rats

less v i t a m i n

a similar

as c o m p a r e d

level

i).

markedly

controls.

response

was

on the 200 p g / k g

A as c o m p a r e d

at the high dose

(Table

showed

a more pronounced

A content

on diets

rats

to u n t r e a t e d

diet at both d o s e - l e v e l s

vitamin

on

had s i g n i f i c a n t l y

group maintained

group

in rats m a i n t a i n e d

rats m a i n t a i n e d

to u n t r e a t e d

(2 p g / k g diet)

exposed

to the m i x e d

significantly

while

at 2 N g / k g

latter c o n g e n e r s

vitamin

Compared

dose-level,

or 1 2 3 6 7 8 - H x C D F

A levels

to the levels

diet

response

resulted

at

in a

to u n t r e a t e d

to the 2 3 7 8 - T C D D

of the m i x e d

diet.

CONCLUSIONS

In the p r e s e n t levels

study

is a g e n e r a l

investigated, obtained

while

it has been d e m o n s t r a t e d effect

non-toxic

data clearly

not o c c u r reduced

feed c o n s u m p t i o n A storage.

The p o t e n c y

potency

to p r o d u c e

The v i t a m i n

but r a t h e r

subchronic

additive

reflects

vitamin

vitamin

an a l t e r e d

The

A reduction

A intake

vitamin

of

A contents

found to be c o m p a r a b l e

(Table

of the m i x t u r e

does

due to

regulation

hepatic

A

so far

this ability.

vitamin

to r e d u c e

and was

toxicity

potency effect

dietary

congeners

was c a l c u l a t e d

A reducing

more or less

PCDD/PCDF-induced

hepatic

PCDDs/PCDFs

seem to lack

of d e c r e a s e d

of the i n d i v i d u a l

to 2 3 7 8 - T C D D

that r e d u c e d

2378-substituted

congeners

show that

as a c o n s e q u e n c e

vitamin

re l a t i v e

of all

to the

2). seemed

of the i n d i v i d u a l

to be in a c c o r d

congeners

(Tables

with

1 and

a

2).

ACKNOWLEDGEMENTS

Inga-Lill

Ohrlund

study was

supported

Protection

Board

and by funds

is t h a n k e d

for her aid in typing

by g r a n t s

(5311235-5),

from K a r o l i n s k a

from the N a t i o n a l the S w e d i s h

Work

the m a n u s c r i p t .

Swedish

This

Environment

Environment

Fund

(84-0139),

Institutet.

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N, P o i g e r N, P o i g e r

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H, H o h b a c h H, H o h b a c h

UG

(1987).

C, S c h l a t t e r C,

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117,

C (1988).

Suter M, S c h l a t t e r

580-586.

Chemosphere

C (1988).

17,

973-984.

Chemosphere

1099-1110. Safe SH, Sokal US.

RR,

Safe

L (1984).

Rohlf

J Agric

JF (1981)

Food Chem

Biometry.

32,

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San Fransisco,

17,