Expression of insulin-like factor 3 protein in the rat testis during fetal and postnatal development and in relation to cryptorchidism induced by in utero exposure to di (n-Butyl) phthalate.
Cryptorchidism is a common reproductive abnormality, possibly resulting from abnormal hormone production/action by the fetal testis. Insulin-like factor 3 (Insl3) is thought to be involved in gubernaculum development and transabdominal testicular descent, but its importance is unclear, due partly to lack of suitable Insl3 antibodies. We generated (by genetic immunization) and validated a novel antirat Insl3 antibody, which we used to characterize immunoexpression of Insl3 in rat Leydig cells (LCs) from fetal life until adulthood and its relationship to cryptorchidism. Immunoexpression was strong on embryonic day (E) 17.5 and E19.5 and from 35 d of age onward but weak from E21.5 until puberty. Because in utero exposure to di (n-butyl) phthalate (DBP) induces cryptorchidism and suppresses Insl3 gene expression, we investigated Insl3 protein expression in fetal and adult rats exposed to 500 mg/kg.d DBP from E13.5 to E21.5. Expression on E17.5 and E19.5 decreased dramatically after DBP exposure, but there was no consistent correlation between this suppression and abnormal testis position. We also compared expression of Insl3 and P450 side-chain cleavage enzyme in fetal testes from rats exposed in utero to DBP or flutamide (50 mg/kg.d). DBP treatment suppressed expression of both P450 side-chain cleavage enzyme and Insl3 at E19.5, but flutamide exposure had no effect on either protein, demonstrating that Insl3 expression in fetal rat LCs is not androgen regulated. In adult rats, Insl3 expression was suppressed in 80% of cryptorchid and 50% of scrotal testes from rats exposed to DBP, suggesting that prenatal DBP exposure also leads to maldevelopment/malfunction of the adult LC population in some animals.
McKinnell
Chris
C
Medical Research Council Human Reproductive Sciences Unit, Centre for Reproductive Biology, The University of Edinburgh Academic Centre, Edinburgh EH16 4TJ, United Kingdom.
Sharpe
Richard M
RM
Mahood
Kim
K
Hallmark
Nina
N
Scott
Hayley
H
Ivell
Richard
R
Staub
Christophe
C
Jégou
Bernard
B
Haag
Friedrich
F
Koch-Nolte
Friedrich
F
Hartung
Stefan
S
D000818:Animals; D003456:Cryptorchidism / Q000139:chemically induced* / Q000196:embryology / Q000473:pathology; D017931:DNA Primers; D003993:Dibutyl Phthalate / Q000633:toxicity*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics*; D007985:Leydig Cells / Q000187:drug effects / Q000502:physiology; D008297:Male; D008856:Microscopy, Fluorescence; D011247:Pregnancy; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013737:Testis / Q000187:drug effects / Q000196:embryology* / Q000254:growth & development
D017931:DNA Primers; D018972:Insulin-Like Growth Factor Binding Protein 3; D003993:Dibutyl Phthalate