Defining a DES “programming window”
2016 Study Abstract
Hypospadias, an abnormality affecting the penile urethra, is one of the most prevalent congenital malformations afflicting human males. The morphology of hypospadias is markedly different in humans versus mice reflecting substantial differences in penile development in humans and mice. Estrogens such as diethylstilbestrol (DES) elicit mouse penile malformations, but the types of penile abnormalities differ depending on whether DES treatment is prenatal or neonatal.
A thorough investigation of the effects of DES over a wide age range of treatment may
- elucidate the morphogenetic mechanisms involved in generating abnormal penile morphology and hypospadias
- and reveal those penile elements more (or less) sensitive on a temporal basis to developmental exposure to DES.
Such an approach may also explain why certain effects of DES elicited and expressed during development resolve to normality in adulthood.
To define the actual “window of susceptibility” to the adverse effects of DES, pregnant mice and their neonatal pups were injected subcutaneously with 200ng/gbw DES every other day
- from embryonic day 12 to 18 (DES E12-E18),
- postnatal day 0 to 10 (DES P0-P10),
- embryonic day 12 to postnatal day 10 (DES E12 to P10),
- postnatal day 5 to 15 (DES P5 to P15),
- and postnatal day 10 to 20 (DES P10 to P20).
Aged-matched controls received sesame oil vehicle. After euthanasia at 10, 15, 20 and 60 days, penises were analyzed by gross morphology, histology and morphometry.
Penises of all 5 groups of DES-treated mice were reduced in size, which was confirmed by morphometric analysis of internal penile structures, and are presumably mediated via signaling through estrogen receptors alpha and/or beta (ERα and ERβ), which have been previously detected in all of the structures affected by DES.
The most profound effects were seen in the DES E12-P10, DES P0-P10, and DES P5-P15 groups, thus defining a DES “programming window”.
For all parameters, DES treatment from P10-P20 showed the most mild of effects.
Adverse effects of DES on the MUMP cartilage and erectile bodies observed shortly after the last DES injection reverted to normality in the DES P5-P15, but not in the E12-P10 and P0-P10 groups, in which MUMP cartilage and erectile body malformations persisted into adulthood, again emphasizing a “window of susceptibility” in the early neonatal period.
- Full study (free access) : Diethylstilbestrol-Induced Mouse Hypospadias: “Window of Susceptibility”, Differentiation, NCBI PubMed PMC4803596, 2016 Jan 20.
- Scanning electron micrographs of human fetal penises at 7 and 10 weeks of gestation. In (A) note the prominent urethral groove. In (B) the edges of the urethral groove are fusing in the midline to form the urethra, but the distal urethral groove is still widely open. Featured image credit PMC4803596/figure/F3.