# Presentation: 121294

## Research Triangle Park,  North Carolina

## One-Generation Extension Study of Vinclozolin and Di-n-Butyl Phthalate Administered by Gavage on Gestational Day 6 to Postnatal Day 20 in CD® (Sprague-Dawley) Rats

*L. Earl Gray, Jr., Ph.D. (EPA)*
*Paul M. D. Foster, Ph.D. (NIEHS)*
*Eric A. Crecelius, Ph.D. (Battelle)*
*Rochelle W. Tyl, Ph.D (RTI International)*
*Julia D. George, Ph.D. (RTI International)*

## BACKGROUND

**This study was performed under a subcontract to Battelle Laboratories, Columbus, Ohio for prime contract No. 68-W-01-023 for the U.S. Environmental Protection Agency**
**One of the tests being considered for inclusion in this screening program is a mammalian, two-generation reproductive toxicity test EPA OPPTS Health Effects Test Guideline 870.3800:  Reproduction and Fertility Effects (U.S. EPA 1998).**
**Although the basic two-generation study design was developed to provide information on insult to the reproductive tract, there is concern that certain effects may be missed, simply because the reproductive tract has not had sufficient time to develop before the observations are made. **
**In the standard two-generation test, most F1 animals are sacrificed and examined at postnatal day (pnd) 21; only one animal per sex per litter is usually allowed to continue to maturity.  These animals are used to breed the F2 generation.  **
**The study design being tested through this work assignment examined whether or not allowing more of the F1 generation males to continue through puberty to adulthood will provide additional information in detecting endocrine-mediated effects.**

## OBJECTIVES

**1. ****	****Whether some of the effects from perinatal exposure to Vinclozolin (VIN) or to Di-n-butyl phthalate (DBP) that can be easily detected after puberty **_**are missed**_** in weanling animals of the F1 generation.**
**2.****	**** Whether some of these effects occur at an incidence that would go undetected  if only one male per litter is retained past puberty and examined at adulthood.**

## HYPOTHESIS

- The “Standard 2-Generation Protocol” cursory examination of up to three F1 males per litter at weaning and only one F1 male at adulthood allows adverse reproductive effects that appear at and after puberty to be missed
-  Examination of three or more F1 males at or after puberty, in addition to the F1 males examined at weaning, will detect additional reproductive effects, and provide a more complete and accurate characterization of the effects of the test compound

***APPROACH***
**Vinclozolin (VIN) and dibutyl phthalate (DBP), two known and well-characterized anti-androgens, were used, each at two doses. **
**The high dose of each compound was a known effect level. **
**The low dose of VIN was expected to produce hypospadias and vaginal pouches that would be hard to detect in weanlings, but easier to detect in adults.  **
**The low dose of DBP was the LOAEL (lowest observable adverse effect level) for this compound.**
**These compounds and the selected doses were identified by basic research protocols, and were used to test this hypothesis in rats.**** **

## Vinclozolin (VIN)

- Chemical Name:		3-(3,5-Dichlorophenyl)-5-ethenyl-5-methyl-2,4-oxazolidinedione
- CAS Number:		5-0471-44-8
- Supplier:		Chem Services, Inc.
- Manufacturer's Batch No.: 	270-71B
- Appearance:		colorless, crystalline solid
- Molecular Formula:		C12H9Cl2NO3
- Molecular Weight:		286.114
- Structure:
- Common use:  		systemic dicarboximide fungicide used on grapes, other fruit, 			vegetables, hops, ornamental plants and turf (Kelce et al., 1997).

## Endocrine-Disrupting Properties of Vinclozolin

- Multigenerational studies in rats indicate that *in utero*/lactational exposure results in demasculinized male offspring (van Ravenzwaay, 1992).
- Gray et al. (1994) confirmed and extended these findings by administering vinclozolin in corn oil by gavage once daily on gd 14 through pnd 3 in rats at 0, 100, or 200 mg/kg/day.  Male offspring exhibited dose-related incidences and severities of male reproductive tract malformations (see below) and renal system malformations, including hydroureter, hydronephrosis, and urinary bladder stones.
*In vitro* studies indicate that the two vinclozolin metabolites bind to the androgen receptor (Kelce et al., 1994a) and, acting as antiandrogens, inhibit subsequent androgen receptor-dependent transcriptional activation (Wong et al., 1995).
- This mechanism has been confirmed *in vivo* (Kelce et al., 1997) with exposure to 200 mg/kg/day vinclozolin, resulting in alteration of the expression of androgen-dependent genes.
- The adverse effects of vinclozolin are mediated by its metabolites (Kelce et al., 1994b).
- The adult rat is also responsive to exposure to vinclozolin, but reproductive tract malformations are, as expected, not produced (Anderson et al., 1995).

- Wistar and Long-Evans rats were orally dosed with vinclozolin from gd 14 to pnd 3 at 200, 12, 6, 3, 1, or 0 mg/kg/day. The high dose (200 mg/kg/day) was maternally toxic, and male offspring from both strains exhibited reduced anogenital distance; retained nipples/areolas; hypospadias; penile hypoplasia; development of a vaginal pouch; hypoplasia and chronic inflammation of the epididymides, prostate, seminal vesicles, and coagulating glands; testicular tubule atrophy; and chronic inflammation of the urinary bladder (Hellwig et al., 2000).
-  At 12 mg/kg/day, retained nipples/areolas were present in both strains in preweanling males but persisted only in Long-Evans rats (Hellwig et al., 2000).
- Long-Evans rats (but not Wistar) also exhibited a low incidence of hypoplasia of accessory sex organs.  The NOAELs (no observable adverse effect level) were therefore 12 mg/kg/day in Wistar rats and 6 mg/kg/day in Long-Evans rats (there were no effects in either strain at 3 or 1 mg/kg/day) (Hellwig et al., 2000).
- Wistar and Long-Evans rats were orally dosed with vinclozolin from gd 14 to pnd 3 at 200, 12, 6, 3, 1, or 0 mg/kg/day (Hellwig et al., 2000).  The high dose (200 mg/kg/day) was maternally toxic, and male offspring from both strains exhibited reduced anogenital distance; retained nipples/areolas; hypospadias; penile hypoplasia; development of a vaginal pouch; hypoplasia and chronic inflammation of the epididymides, prostate, seminal vesicles.
- Maternal rats were dosed by gavage on gd 14 through pnd 3 with vinclozolin at 0, 100, and 200 mg/kg/day (first study), with expected male offspring reproductive malformations observed at both doses (Gray et al., 1994).

## Di-butylphthalate (DBP)

- CAS Number:		84-74-2
- Supplier:		Sigma-Aldrich, Inc.
- 	 Manufacturer's Batch No.:	080K1023
- 	Appearance:		clear, colorless liquid
- 	Molecular Formula:		C16H22O4
- 	Molecular Weight:		278.35
- Chemical Structure:
- Common use:		a coalescing aid in latex adhesives, as a 					plasticizer in cellulose plastics, and as a solvent 				in dyes.

## Dibutylphthalate (DBP) cont’d.

- Exposure during gestation results in developmental toxicity, and DBP crosses the placenta in rats (Saillenfait et al., 1998; Ema et al., 1993, 1994, 1995a, 1998). The intestinal metabolite, mono-n-butyl phthalate, also causes developmental toxicity in rats; this is most likely the proximate toxicant (Ema et al., 1995b).
- Although DBP acts as an antiandrogen, it does not bind to the androgen receptor (Foster et al., 2000)
- DBP apparently acts by inhibiting fetal testicular testosterone biosynthesis *in vitro* and *in vivo* (Mylchreest et al., 1999).  In adult rats, it also causes testicular toxicity but, as expected, no malformations (Cater et al., 1977).  Daily oral (gavage) administration of DBP to dams, during gestation and lactation of 100 mg/kg/day through 750 mg/kg/day, results in dose-related reproductive malformations in male offspring, with approximately 75% of the male offspring affected at 750 mg/kg/day.  The male malformations include shortened anogenital distance, small flaccid testes, agenesis of portions (caput, corpus, cauda) of or the entire epididymis, delayed puberty, retained nipples and areolae, etc. (Gray et al., 1998; 2000).
- An oral dose of 50 mg/kg/day has been defined as the NOAEL by Mylchreest et al. (1998a,b, 1999).  Therefore, for this study, DBP in corn oil will be administered by oral gavage once daily on gd 6 through pnd 21 at 0 (vehicle control), 100 mg/kg/day (the LOAEL; lowest observed adverse effect level), and at 500 mg/kg/day (an obvious effect level).

## One-Generation Extension Study Design and Target Doses

***One-Generation Extension Study Design and Target Doses***

## One-Generation Extension Target Doses

## Summary of F0 Maternal Data

- Mean periodic maternal body weights and weight gains
- Feed consumption (expressed as g/animal/day and g/kg body weight/day) during gestation and lactation
- Survival indices
- Gestational length
- Mean litter size
- Mean number of live and dead offspring
- Prenatal (postimplantation) loss (%)  =
- Number and percent of mothers showing treatment-related behavioral abnormalities in nesting and nursing
- Gestational index (%)  =
- Gross necropsy
- Number of uterine nidation scars at necropsy

## Summary of F1 Litter Lactational Data 

- Total litter size
- Number and percent of stillborn
- Number and percent of live births
- Anogenital distance and body weight on pnd 0 and 21
- Periodic viability counts
- Periodic body weights by sex per litter from birth to weaning (taken on pnd 0, 4, 7, 14, and 21 by individual pup)
- Sex ratio (% males per litter)

## Summary of F1 Litter Lactational Data Cont.

- 	**Live Birth/Survival Indices**:
- 	Live birth index: =
- 	4-day survival index  =
- 	7-day survival index  =
- 	14-day survival index  =
-                 21-day survival index  =
-                 Lactation index  =
-                 Number of male pups per litter with (and number per male of) areolae and/or nipples on pnd 11-13 and 21

## 	Summary of Data From Retained Male F1 Offspring

- Mean periodic body weights and weight gains
- Age and body weight at acquisition of preputial separation
- Organ weights
- Reproductive system external and/or gross abnormalities
- Presence of areolae and/or nipples at adult necropsy
- Anogenital distance at adult necropsy

## External and Internal Examination of F1 Males at Necropsy (pnd 21 or 95)

- Each male selected for pnd 21 necropsy or pnd 95 adult necropsy was examined:
- Externally
- Nipples and areolae were counted and position recorded
- hypospadias, epispadias, and cleft phallus
- AGD was measured
- Undescended testes
- Preputial separation
- Location of each testis (scrotal, abdominal, gubernaculum attached to abdominal wall)
- Gubernacular cords, present or absent and length in mm
- Presence of cranial suspensory ligaments
- Testes which were small, absent, fluid filled, enlarged, appeared infected, or other
- Epididymides which were small, absent, or infected (including region of effects)
- Ventral prostate which was small, absent, or infected
- Dorsolateral prostate which was small, absent, or infected
- Seminal vesicles which were small, absent, infected, or one side larger than the other
- Coagulating glands which were small, absent, infected, one side larger than the other, or detached from seminal vesicles

## Slide 19

## Pnd 21 Necropsy

-                              Guideline Two-Gen Study
- Weights:
- 	Body				X
- 	Brain				X
- 	Spleen				X
- 	Thymus			X
- 	Liver
- 	Adrenal
- 	Testis
- 	Corpus/Caput Epidiymis
- 	Cauda Epididymis
- 	Seminal Vesicles/Coagulating Gland
- 	Prostate
- 	LABC
- 	Cowper’s Glands

-                       Extended One-Gen
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X

## Pnd 21 Necropsy

-                              Guideline Two-Gen Study
- AGD
- Areolae
- Nipples
- Hypospadias
- Epispadias
- Cleft Phallus
- Soiled Inguinal Region
- Gubernacular Cord a
- Cranial Suspensory Ligaments a
- a Present/Absent; Length

-                       Extended One-Gen
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X
- 			X

## Can this study design and the performing laboratory detect both doses of both test compounds (VIN and DBP) as effect levels? 

## Both doses of both test chemicals were detected as effect levels in preweanling males by pnd 13, based on retention of areolae

## Slide 24

## Slide 25

## Slide 26

## Both doses of VIN and the high dose of DBP were detected as effect levels from data on AGD at birth.  This effect persisted throughout the study to pnd 95. 

- Both doses of VIN and the high dose of DBP were detected as effect levels from data on AGD at birth.  This effect persisted throughout the study to pnd 95.

## Slide 28

## Slide 29

## Slide 30

## The incidence of nipples on pnd 11-13 males was significantly increased for both doses of VIN and for the high dose (but not the low dose) of DBP.  

- The incidence of nipples on pnd 11-13 males was significantly increased for both doses of VIN and for the high dose (but not the low dose) of DBP.
- Since retained nipples are not observed in control males, and retained areolae are (at 0-3.5% incidence in the performing laboratory), the anticipation was that retained nipples would be a more sensitive indicator of anti-androgenic activity than retained areolae.

## Slide 32

## Slide 33

## Slide 34

## Were male reproductive system malformations detected at the pnd 21 necropsy for both test chemicals at both doses? 

## Slide 36

## In utero/lactational exposure to both doses of both test chemicals resulted in male reproductive system

-  malformations in a dose-related incidence and severity.
- The male reproductive malformations at the low dose of DBP were biologically significant (never observed in controls) but clearly not statistically significant. They included missing Cowper's glands and presence of cranial suspensory ligaments (normally observed only in females).

## Were male reproductive system malformations detected at pnd 95

**Were male reproductive system malformations detected at pnd 95**
** ****for both test chemicals at both doses?**** **

## Slide 39

## Slide 40

## In utero/lactational exposure to both test chemicals at both doses  resulted in male reproductive system malformations in a dose- and chemical-related incidence and severity on pnd 95.  For the low dose DBP, findings included cleft phallus, dorsal and ventral prostate lobes reduced in size, and enlarged testes.  Admittedly, these were observed at a low incidence at this dose, but they were biologically significant although not likely statistically significant.

## Did the F1 males that died or were sacrificed moribund also exhibit male reproductive malformations?  

**Did the F1 males that died or were sacrificed moribund also exhibit male reproductive malformations?  **
- There were two F1 males each at the VIN high dose and the DBP high dose that died or were sacrificed moribund.  They did exhibit the same male reproductive system malformations as those observed in the adult males at scheduled necropsy.

## Slide 43

## Were the incidences of findings present at both pnd 21 and 95 necropsies different? 

**Were the incidences of findings present at both pnd 21 and 95 necropsies different? **
** ****Were they greater on pnd 95? **
** ****Would they have been detected on pnd 95 with only one male evaluated per litter? **

## Slide 45

## Slide 46

## Male malformations observed on pnd 95 but not on pnd 21 in either or both test chemicals or in both dose groups per chemical include the following:

**Male malformations observed on pnd 95 but not on pnd 21 in either or both test chemicals or in both dose groups per chemical include the following:**
- epididimides reduced in size/abnormal (not observed in either VIN groups on pnd 21)
- epispadias (not detected in any group on pnd 21)
- levator ani bulbocavernosus (LABC) complex, missing/reduced in size (not observed in the low dose of VIN or either dose of DBP on pnd 21)
- cleft phallus (not observed in the low dose of DBP on pnd 21)
- dorsal and/or ventral lobes of prostate reduced in size/abnormal (not detected in any group on pnd 21)
- seminal vesicles missing/reduced in size/abnormal (not observed in the low dose of VIN on pnd 21)
- undescended testes (not observed in the low dose of VIN on pnd 21)
- testes reduced in size or flaccid/soft (not detected in any group on pnd 21)
- vaginal pouch (not detected in any group on pnd 21)

## Were there differences in the effects on weights of various male reproductive system organs between the two chemicals at the same time point?

**Were there differences in the effects on weights of various male reproductive system organs between the two chemicals at the same time point?**
**VIN:**
- Seminal vesicle and coagulating gland
- prostate
- LABC
- Cowper’s gland
**DBP:**
- testes
- epididymides

## Were there differences in the effects on weights of various male reproductive system organs within each chemical at the two different time points? 

**Were there differences in the effects on weights of various male reproductive system organs within each chemical at the two different time points? **

## Slide 50

## Slide 51

## Slide 52

## Slide 53

## In addition to addressing the specific objectives stated above, 

**the data in this study invite comparison of the effects of these antiandrogens that work through different mechanisms**

## Slide 55

## Would effects observed on pnd 95 have been observed if we only examined one adult male per litter in each group?

**CONCLUSIONS**
- Specific male offspring malformations were detected on pnd 95 but not on pnd 21. Examples include prostate dorsal lobe abnormal/reduced in size (VIN, both doses; DBP, high dose), prostate ventral lobe abnormal/reduced in size (both compounds, both doses), and epispadias (VIN, both doses).
- The incidence of specific male offspring malformations detected on pnd 95 was higher than the incidence of the same malformation observed on pnd 21.  Examples include agenesis of all or parts of the epididymis(des) (high dose of both VIN and DBP), hypospadias (low dose VIN), and missing/reduced in size/abnormal seminal vesicles (high dose of both VIN and DBP).
- The effects of VIN on the incidence of hypospadias and ventral prostate agenesis were more obvious at pnd 95 than at pnd 21.  This effect was more apparent at the low dose than at the high dose.  Specifically, hypospadias was observed in 9.7% vs 15.8% of the animals on pnd 21 and 95, respectively, whereas high dose animals exhibited hypospadias at 80.0% vs 98.6% on pnd 21 and 95, respectively.
- The effects of DBP (high dose) on the incidence of epididymal agenesis on pnd 95 was approximately twice that observed on pnd 21, and thus were more obvious on pnd 95 than on pnd 21.
- Adverse effects on the weight of some male reproductive tissues were more apparent at pnd 95 than on pnd 21.  Examples include adjusted right or left testis weight (high dose VIN), absolute right cauda epididymis weight (low dose VIN), adjusted right cauda epididymis weight (low dose VIN and DBP), absolute LABC weight (low dose VIN), adjusted LABC weight (high dose VIN and DBP), and absolute and adjusted Cowper’s gland weight (high dose VIN).

## CONCLUSIONS (CONTINUED)

- Adverse reproductive system effects *in toto* (structural malformations and other abnormalities) of the low and high doses of VIN and the high dose of DBP on F1 adult male offspring would most likely be statistically significant with either one or three adult males/litter, and would have been detected with either study design.
- Adverse reproductive system structural effects *in toto* at the low  dose of DBP on F1 adult male offspring were clearly biologically significant but not necessarily or likely statistically significant, with either one or three adult males/litter, and provide an example of effects that would not be detected with either study design.
- The more males examined per litter, the better the characterization of the litter as responding or not responding adversely to exposure, and the smaller the variance term for pooled litters within each treatment group.  The enhanced sensitivity with more males examined per litter would increase the likelihood of detection of effects as statistically and biologically significant.
- Also, for effects with low  incidence, such as in the low dose DBP group in this study, the risk with fewer males examined per litter is that the effect might be missed, i.e., the litter would be designated as not responding, on the basis of the one male examined, if that male did not exhibit the effect.

## ACKNOWLEDGEMENTSThis study was performed under a subcontract to Battelle Laboratories, Columbus, Ohio for prime contract No. 68-W-01-023 for the U.S. Environmental Protection Agency

**Laboratory Staff (RTI International)**
- Ms. M.C. Marr (Laboratory Supervisor),
- Ms. C.B. Myers (Reproductive Toxicity Study Supervisor and Data Analyst)
- Mr. W.P. Ross
- Ms. M.C. Rieth
- Ms. V.I. Wilson
- Ms. L.B. Pelletier
- Ms. M.P. Gower
- Ms. N.M. Kuney
- Ms. R.T. Krebs
- Ms. S.W. Pearce
- Ms. K.D. Vick
- Ms. L. McDonald
- Ms. A.J. Parham
- Mr. M.D. Crews
- Mr. C.G. Leach
- Ms. A. Goodman
- Ms. D. B. Bynum

**Chemistry**
- Dr. E.A. Crecelius, PNNL, Battelle Marine Sciences Laboratory, Sequim, WA.
- Mr. M.M. Veselica, Supervisor, RTI Materials Handling Facility
- Mr. D.L. Hubbard
- Mr. R.A. Price
**Animal Care (RTI International)**
- Dr. D.B. Feldman, DVM, ACLAM, Veterinarian
- Mr. F.N. Ali, Manager of RTI Animal Research Facility
**Quality Assurance**
- Ms. D.J. Smith (RTI)
- Ms. M.D. Phillips (RTI)
- Ms. T.M. Kenney (RTI)
- Ms. C. Sexsmith, QA Consultant
- Ms. K. Cummings (ILS)
- Ms. T.Pollock (Battelle)

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