Vitamin D status predicts reproductive fitness in a wild sheep population

Vitamin D deficiency has been associated with the development of many human diseases, and with poor reproductive performance in laboratory rodents. We currently have no idea how natural selection directly acts on variation in vitamin D metabolism due to a total lack of studies in wild animals. Here, we measured serum 25 hydroxyvitamin D (25(OH)D) concentrations in female Soay sheep that were part of a long-term field study on St Kilda. We found that total 25(OH)D was strongly influenced by age, and that light coloured sheep had higher 25(OH)D(3) (but not 25(OH)D(2)) concentrations than dark sheep. The coat colour polymorphism in Soay sheep is controlled by a single locus, suggesting vitamin D status is heritable in this population. We also observed a very strong relationship between total 25(OH)D concentrations in summer and a ewe’s fecundity the following spring. This resulted in a positive association between total 25(OH)D and the number of lambs produced that survived their first year of life, an important component of female reproductive fitness. Our study provides the first insight into naturally-occurring variation in vitamin D metabolites, and offers the first evidence that vitamin D status is both heritable and under natural selection in the wild

Maternal vitamin D deficiency leads to cardiac hypertrophy in rat offspring

The aim of this study was to determine the effect of vitamin D deficiency from conception until 4 weeks of age on the development of the heart in rat offspring. Sprague-Dawley (SD) rats were fed either a vitamin D deplete or vitamin D-replete diet for 6 weeks prior to pregnancy, during pregnancy and throughout lactation. Cardiomyocyte number was determined in fixed hearts of offspring at postnatal day 3 and 4 weeks of age using an optical disector/fractionator stereological technique. In other litters, cardiomyocytes were isolated from freshly excised hearts to determine the proportion of mononucleated and binucleated cardiomyocytes. Maternal vitamin D deficiency had no effect on cardiomyocyte number, cardiomyocyte area, or the proportion of mononucleated/binucleated cardiomyocytes in 3-day-old male and female offspring. Importantly, however, vitamin D deficiency led to an increase in left ventricle (LV) volume that was accompanied by an increase in cardiomyocyte number and size, and in the proportion of mononucleated cardiomyocytes at 4 weeks of age. Our findings suggest that exposure to vitamin D deficiency in utero and early life leads to delayed maturation and subsequent enhanced growth (proliferation and hypertrophy) of cardiomyocytes in the LV. This may lead to altered cardiac function later in life