Male Reproductive Tract Lesions at 6, 12, and 18 Months of Age Following in Utero Exposure to Di(n-butyl) Phthalate

Abstract

In utero exposure of male rats to the antiandrogen di(n-butyl) phthalate (DBP) leads to decreased anogenital distance (AGD) on postnatal day (PND) 1, increased areolae retention on PND 13, malformations in the male reproductive tract, and histologic testicular lesions including marked seminiferous epithelial degeneration and a low incidence of Leydig cell (LC) adenomas on PND 90. One objective of this study was to determine the incidence and persistence of decreased AGD, increased areolae retention, and LC adenomas in adult rats following in utero DBP exposure. A second objective was to determine whether AGD and areolae retention during the early postnatal period are associated with lesions in the male reproductive tract. Pregnant Crl:CD(SD)BR rats were gavaged with corn oil or DBP at 100 or 500 mg/kg/day, 10 dams per group. Three replicates of rats (n = 30 rats per replicate) were exposed from gestation day 12 to 21 and the male offspring allowed to mature to 6, 12, or 18 months of age. Gross malformations in the male reproductive tract and histologic lesions in the testes were similar to those previously described. However, testicular dysgenesis, a lesion of proliferating LCs and aberrant tubules that has not been previously described in DBP-exposed testes, was diagnosed. The incidence of this lesion was approximately 20% unilateral and 7-18% bilateral in the high-dose group and was similar among all ages examined, implicating a developmental alteration rather than an age-related change. AGD and areolae retention were found to be permanent changes following in utero exposure to 500 mg/kg/day of DBP. Decreased AGD was a sensitive predictor of lesions in the male reproductive tract, relatively small changes in AGD were associated with a significant incidence of male reproductive malformations. In utero DBP exposure induced proliferative developmental lesions, some of which would have been diagnosed as LC adenomas by the morphological criteria set forth by the Society of Toxicologic Pathology. However, these lesions were dissimilar to traditional LC adenomas as the LCs were poorly differentiated and the lesions contained aberrant seminiferous tubules. While the morphology and incidence of this DBP-induced testicular developmental lesion has been fully characterized by this study, the detailed pathogenesis warrants further investigation.

Retraction: <i>In utero</i>-exposed di(<i>n</i>-butyl) phthalate induce dose dependent, age-related changes of morphology and testosterone-biosynthesis enzymes/associated proteins of Leydig cell mitochondria in rats

“…We have mainly studied di(n-butyl) phthalate (DBP), the phthalate prepared from butanol Wakui et al, 2013Wakui et al, , 2014. DBP is widely used as a plasticizer and the general population appears to be exposed to it in disproportionately higher amounts compared to other phthalates (Blount et al, 2000;Barlow et al, 2003Barlow et al, , 2004.…”

“…As a function of the alcohol chain length, they may be separated into two distinct groups: i) low molecular-weight phthalates containing three to six carbons in the ester functionality, and ii) high molecular-weight phthalates that contain greater than six carbons in the ester functionality (Blount et al, 2000;Barlow and Foster, 2003;Barlow et al, 2004). Phthalates are used to impact product flexibility, durability, transparency, and longevity; and are present in many common products; children's toys, cosmetics, detergents, electronics, food packaging, paints, personal care products, pharmaceuticals, and waxes (Wolf et al, 1999;OSHA, 2009;Hannas et al, 2011;Johnson et al, 2011Johnson et al, , 2012Guo et al, 2013).…”

Involvement of testicular growth factors in fetal Leydig cell aggregation after exposure to phthalate in utero

“…FLCs were aggregated rather than dispersed when doses of DEHP were increased. Previous studies similarly reported that high-dose exposures to DEHP or DBP in utero resulted in focal disruptions in the structure of the seminiferous epithelium and in abnormal aggregations of FLCs (24,25). Stereological analyses have suggested that the increased FLC number per cluster in response to DEHP does not result from increased Leydig cell numbers (our results and ref.…”

Effects of Flutamide on Sex Maturation and Behavior of Offspring Born to Female Rats Treated During Late Pregnancy

“…ers have reported similar effects of flutamide (Miyata et al, 2002;McIntyre et al, 2001) and other antiandrogen agents (Shono et al, 2004;Barlow et al, 2004;Ema et al, 2003;Bowman et al, 2003) on sexual maturity in males. Miyata et al (2002) reported that oral administration of flutamide at ≥ 2.5 mg/kg/day from GD 14 to PND 3 decreased AGD, and McIntyre et al (2001) observed similar findings at oral doses of 6.25 mg/kg/day.…”