Bull. Environ. Contam. Toxicol. (1988)41:496-501 �9 1988 Spdnger-Vedag New York Inc.

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

~and Toxicology

p,p'-DDT is an Estrogenic Compound

Sergio Bustos, Juan C. Denegri, Fernando Diaz, and Andrei N. Tchernitchin

Laboratory of Experimental Endocrinology, Department of Experimental Morphology, University of Chile Medical School, Casilla 21104, Correo 21, Santiago, Chile

DDT ( l , l , l - t r i c h l o r o - 2 , 2 - b i s [ c h l o r o p h e n y l ] ethane i s an i n s e c t i c i d e s t i l l i n d i s c r i m i n a t e l y used i n severa l Th i rd World c o u n t r i e s (Me tca l f 1973). Of the two i s o - mers, p,p'-DDT i s considered the l e a s t t o x i c and t h e r e - fo re the more app rop r i a t e f o r use. The wide use of DOT i s known to contaminate the envi ronment , i n c l u d i n g food. Th is con tamina t ion makes impor tan t the i n v e s t i g a - t i o n of i t s t o x i c e f f e c t s i n mammals ( A l b e r t 1981). o,p'-DDT has been repor ted to e x e r t e s t r o g e n - l i k e ac- t i v i t y (Foster e t a l . 1975; Kupfer 1975; Kupfer and Bulger 1976). I t b inds to c y t o s o l estrogen recep to rs (Kupfer and Bulger 1977) and induces severa l es t rogen i c responses, such as increases i n r a t u t e r i n e wet and dry we igh t , p r o t e i n and glycogen c o n c e n t r a t i o n s (McBlain 1987) and inc rease i n thymid ine i n c o r p o r a t i o n i n t o u t e r i n e DNA (Galand e t a l . 1987; McBlain 1987). In con- t r a s t to o,p ' -DDT, i t s p , p ' - i s o m e r was repor ted to d i s - p lay a much lower or u n e x i s t e n t es t rogen i c a c t i v i t y (Foster e t a l . 1975; Galand e t a l . 1987; Nelson 1974; Robinson e t a l . 1984; Stancel e t a l . 1980).

The responses to estrogen i n the u te rus can be c l a s s i - f i e d i n t o separate groups t h a t are mediated by d i f f e r - ent k ind o f estrogen recep to rs through independent mechanisms ( T c h e r n i t c h i n 1983; T c h e r n i t c h i n e t a l . 1985). Th is independence between mechanisms a l l ows the d i s s o c i a t i o n between the va r i ous es t rogen i c responses; i . e . , t h e i r s e l e c t i v e s t i m u l a t i o n or i n h i b i t i o n ( T c h e r n i t c h i n e t a l . 1985). F u r t h e r , there e x i s t e s t r o - genic compounds ( e s t r i o l , e q u i l i n , n a f o x i d i n e , d i e t h y l - s t i l b e s t r o ] ) t h a t s e l e c t i v e l y induce responses mediated by one of these mechanisms but not o t he r s , because of t h e i r d i f f e r e n t i a l a f f i n i t y f o r recep to rs i n v o l v e d i n these responses (Galand e t a l . 1984; Gruner t e t a l .

Send r e p r i n t requests to A.N. T c h e r n i t c h i n a t the above address.

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1986; T c h e r n i t c h i n 1972; T c h e r n i t c h i n e t a l . 1975, 1985). Taking above i n t o c o n s i d e r a t i o n , i t i s p o s s i b l e t h a t p,p '-DDT may s e l e c t i v e l y induce es t r ogen i c responses i n some c e l l - t y p e s but no t i n o t he r s , and t h a t these e f f e c t s might remain undetected by the c l a s - s i c a l b iochemical techn iques t h a t do not d i s c r i m i n a t e among the v a r i o u s u t e r i n e c e l l - t y p e s (S runer t e t a l . I786; T c h e r n i t c h i n e t a l . 1985). The present s tudy i n - v e s t i g a t e d the es t rogen i c responses o f p,p'-DDT a c t i o n sepa ra te l y i n the d i f f e r e n t u t e r i n e c e l l - t y p e s .

MATERIALS AND METHODS

Four groups of immature female Sprague-Dawley r a t s , o f 40 to 49 g body w t . , were used i n the present s tudy ; 5 to 8 animals comprised each group. The two exper imenta l groups were i n t r a v e n o u s l y i n j e c t e d w i t h 0 .5 mg p,p'-DDT i n 0 . I ml d imethy l s u l f o x i d e (DMSO); the c o n t r o l groups were i n j e c t e d w i t h equal amounts of v e h i c l e . The u t e r i were exc ised under e the r anes thes ia & or 24 h a f t e r t rea tment , f i x e d i n 10% n e u t r a l f o r m a l i n , and h i s t o l o g - i c a l l y processed f o r f u r t h e r s t u d i e s ( T c h e r n i t c h i n and Baland 1983). The f o l l o w i n g es t rogen i c responses were i n v e s t i g a t e d : myometr ial hyper t rophy , measured as i n - crease i n the r e c i p r o c a l va lue of c e l l d e n s i t y (RVCD) i n c i r c u l a r myometrium, and edema i n deep and i n su- p e r f i c i a l endometr ia l stroma~ measured as increases i n RVCD i n these h i s t o l o g i c a l l o c a t i o n s (S runer t e t a l . 198&).

The Least S i g n i f i c a n t D i f f e r e n c e (LSD) a p D s t e r i o r i t e s t was used f o r comparison between exper imen ta ls and c o n t r o l s and between & and 24 h o f t rea tment . The com- mon va r iance needed f o r t h i s t e s t was est imated from a one-way unbalanced a n a l y s i s o f va r i ance (ANOVA).

RESULTS AND DISCUSSION

The data on the e f f e c t o f an i n t r avenous i n j e c t i o n o f 0 .5 mg p,p'-DDT on RVCD i n c i r c u l a r myometrium, deep endometr ia l stroma and s u p e r f i c i a l endometr ia l stroma, & or 24 h a f t e r t rea tment , i s shown i n F igu re 1. I t can be observed t h a t the i n s e c t i c i d e induces a h y p e r t r o p h i c response i n c i r c u l a r myometrium and an edematous response i n deep and i n s u p e r f i c i a l endometrium, a t 24 h a f t e r t rea tment . These responses were not detected a t & h a f t e r t rea tment .

The present r e s u l t s show t h a t p,p ' -DDT, considered as the l e a s t t o x i c DDT isomer and t h e r e f o r e the most ap- p r o p r i a t e f o r use, d i s p l a y s es t rogen i c a c t i v i t y i n d u c - ing both myometr ia l hyper t rophy and endomet r ia l edema. I t i s w e l l documented t h a t myometr ial hyper t rophy i s a genomic response to est rogen (S runer t e t a l . 1984) t h a t

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24 g TIME AFTER TREATMENT

F i g u r e i . E f f e c t of pTp'-DDT on the r e c i p r o c a l va lue of c e l l d e n s i t y (RVCD) in deep and in s u p e r f i c i a l endome- t r i a l stroma and in c i r c u l a r myometrium. In comparisons between DDT-t reated r a t s (hatched bars) and c o n t r o l s (open bars)~ the l i m i t s of S i g n i f i c a n c e a t the l e v e l s ;f p=O.O5 and p=O.Ol are shown by the h o r i z o n t a l dot ted

and broken l i n e s r e s p e c t i v e l y . $p<O.O01 in comparisons between & and 24 h of t r e a t m e n t .

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i s mediated by the c y t o s o l - n u c l e a r recep to rs , and tha t endometr ia l edema i s a non-genomic response to estrogen (Tchern i t ch in and Galand 1982) mediated by estrogen r e - ceptors located in the eos inoph i l s (Tchern i t ch in 1983). The e f f e c t s o f the p e s t i c i d e suggest i t s i n t e r a c t i o n w i th both kind of estrogen receptors in the r a t u te rus : the c y t o s o l - n u c l e a r receptors and the eos inoph i l e s t r o - gen receptors .

Taking i n t o cons ide ra t ion (a) the prolonged h a l f l i f e of DDT, (b) the p o t e n t i a l l y carc inogenic e f f e c t o f v a r - ious estrogens on the g e n i t a l t r a c t o f the e I d e r l y , and (c) the p o t e n t i a l l y dangerous permanent e f f e c t s of v a r - ious es t rogen ic compounds on women t h a t were exposed in u tero to them, as i t has been shown in o f f s p r i n g of pregnant women exposed to d i e t h y l s t i l b e s t r o l ( Iguch i e t a l . 198&). the present r e s u l t s should a l e r t r e g u l a t o r y o f f i c i a l s of the p o t e n t i a l danger of the i n d i s c r i m i n a t e use of DDT.

Therefore, based on the present r e s u l t s and on p r e v i - ous ly reported data, we a l e r t a u t h o r i t i e s about the need to con t ro l the use and abuse of DDT to avoid un- wanted s ide e f f e c t s in the popu la t ion . This cons idera- t i o n i s impor tant in Third World coun t r i es such as Ch i l e , where a t present t h i s compound i s used almost f r e e l y w i thou t any e f f i c i e n t con t ro l a t a l l .

AcknoHledgments. Supported in pa r t by grant B-2684-8715 from the U n i v e r s i t y of Ch i l e . We thank Dagoberto S&ez~ Eugenio A s t u d i l l o and M. Isabel Montero f o r exper t t echn i ca l ass is tance .

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Tche rn i t ch in AN, Mena MA, Rodrlguez A, Maturana M (1985) Radioautographic l o c a l i z a t i o n o f estrogen r e - ceptors in the r a t u te rus : a too l f o r the study o f c l a s s i c a l and n o n t r a d i t i o n a I mechanisms of hormone ac- t i o n . In : Pertschuk LP, Lee SH (eds) L o c a l i z a t i o n o f P u t a t i v e S te ro id Receptors vol I . Experimental Systems. CRC Press, Boca Raton, F lor ida~ pp 5-37

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Received February 29, 1988; accepted A p r i l 28, 19SB.

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