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The estrogenic and antiandrogenic pesticide methoxychlor alters the reproductive tract and behavior without affecting pituitary size or LH and prolactin secretion in male rats.

Abstract：

:This study was designed to determine if long-term exposure to high doses of methoxychlor (M) would alter pituitary or testicular endocrine functions in either an estrogenic or antiandrogenic manner. Weanling male Long-Evans hooded rats were dosed daily with M (po) at 0, 200, 300, or 400 mg kg-1 day-1 for 10 months. Methoxychlor treatment delayed puberty by as much as 10 weeks and reduced fertility and copulatory plug formation in a dose-related manner at the initial mating. During mating, M-treated males exhibited shorter latencies to mount and ejaculate versus control males, but the number of intromissions prior to ejaculation was unaffected, indicating that M enhanced the arousal level in the males in an estrogen-dependent manner. Most treated males eventually mated but time-to-pregnancy was lengthened. Very low sperm counts were associated with infertility, while prolonged delays in puberty reduced fecundity. Methoxychlor treatment with 200 to 400 mg kg-1 day-1 failed to mimic the chronic effects of a sustained (8 months) low dose of estradiol-17 beta (3-mm silastic implants) on pituitary or testicular hormone levels. Estradiol administration increased pituitary weight 4-fold, serum levels of luteinizing hormone (LH) were reduced by almost 50%, and serum prolactin was increased 40-fold, while M did not affect any of these measures. These data demonstrate that M affects the CNS, epididymal sperm numbers, and the accessory sex glands and delays mating without significantly affecting the secretion of LH, prolactin, or testosterone. These data indicate that M did not alter pituitary endocrine function in either an estrogenic or antiandrogenic manner. To our knowledge, these data provide the first in vivo example of such a pronounced degree of target tissue selectivity to an environmental endocrine-disrupting chemical.

journal_name

Toxicol Ind Health

journal_title

Toxicology and industrial health

authors

Gray LE Jr,Ostby J,Cooper RL,Kelce WR

doi

10.1177/074823379901500105

subject

Has Abstract

pub_date

1999-01-01 00:00:00

pages

37-47

issue

1-2

eissn

0748-2337

issn

1477-0393

journal_volume

pub_type

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The estrogenic and antiandrogenic pesticide methoxychlor alters the reproductive tract and behavior without affecting pituitary size or LH and prolactin secretion in male rats.