Increased plugging latency in cycling epiERα −/− (Esr1 f/− Wnt7a Cre/+ ) mice

Wnt7a-Cre is a commonly used driver for generating uterine epithelial conditional knockout mice, such as epiERα -/- (Esr1 f/- Wnt7a Cre/+ ) and epiPR -/- (Pgr f/- Wnt7a Cre/+ ). We noticed that epiERα -/- females, but not epiPR -/- females, have prolonged plugging latency, which is the duration between continuous cohabitation and detection of the first vaginal plug (a sign of mating). Mating occurs in proestrus and/or estrus stages of the estrous cycle. Vaginal cytology detected estrous cyclicity in all mice examined, although epiERα -/- mice had leukocyte-dominant vaginal cytology throughout the estrous cycle and their estrous cyclicity appeared less regular. Estrous cyclicity and mating activity are regulated by the hypothalamic-pituitary-ovarian axis, in which kisspeptin plays essential roles. ERα and PR are expressed in the rostral periventricular area of the ventricle (RP3V) and arcuate nucleus (ARC) kisspeptin neurons in the hypothalamus. It has been reported that Esr1 f/f Kiss1-Cre mice lack estrous cyclicity, while Pgr f/f Kiss1-Cre mice have normal estrous cyclicity at two months old, and Wnt7a is highly expressed in ARC. The prolonged plugging latency in epiERα -/- mice could be contributed by the deletion of ERα in Wnt7a-positive cells in ARC. Wnt7a-Cre was also used to generate uterine epithelial RhoA-deficient mice, epiRhoA -/- (RhoA f/- Wnt7a Cre/+ ). However, both female and male RhoA f/- Wnt7a Cre/+ mice had hydrocephalus and died within a few weeks of age. Our observations of increased plugging latency in epiERα -/- mice and hydrocephalus in RhoA f/- Wnt7a Cre/+ mice exemplify unintended neuronal gene deletion using Wnt7a-Cre for uterine epithelial-specific gene deletion.