Prenatal Exposure to Continuous Constant Light Alters Endochondral Ossification of the Tibiae of Rat Pups

Abstract

Clinical and experimental studies suggest that prenatal exposure to stress can impact the growth and development of offspring. The effect of prenatal exposure to constant light, applied as a chronic stressor, on endochondral ossification of the tibiae of 3-day-old and 15-day-old pups was histomorphometrically evaluated. Pregnant rats were divided into 2 groups: mothers chronically exposed to a 12:12-hour light/light cycle (LL) and control mothers maintained on a 12:12-hour light/dark cycle on days 10-20 of pregnancy. On postnatal days 3 and 15, the pups were weighed and euthanized. The tibiae were resected and histologically processed to obtain sections for hematoxylin and eosin staining (HE) and tartrate-resistant acid phosphatase (TRAP) histochemistry, in order to perform histomorphometric determinations. The data were statistically analyzed. A significant decrease in hypertrophic cartilage thickness was observed in the tibiae of the 3-day-old (LL: 0.134 ± 0.02 vs. controls: 0.209 ± 0.023 mm; p < 0.01) and 15-day-old (LL: 23.32 ± 3.98 vs. controls: 22.96 ± 1.93 mm; p < 0.05) prenatally stressed pups. The subchondral bone volume was significantly lower in the tibiae of the 3-day-old LL pups (38.83 ± 6.14%) than in the controls (62.83 ± 10.67%; p < 0.01). The decrease in subchondral bone volume and hypertrophic cartilage thickness shows that the normal growth process of the tibia is impaired in prenatally stressed pups.

The Pyramid Counteracts Chronic Prenatal Restraint-Stress Effects on the Milestones, Anthropometry, and Body, Brain and Adrenal Gland Weights of Pups in Rats

“…10 -11 Dancause et al have reported prenatal stress results in shorter long bones in adulthood, independently of effects on overall body size. 24 The present study adds to a growing body of evidence suggesting prenatal stress is a risk factor for not only poor linear growth of bones as earlier reported, 23,25 but also the overall postnatal physical development of the pups. Maternal stress retards foetal development in rats with delay in the postnatal milestones.…”

Gestational jet lag predisposes to later-life skeletal and cardiac disease

“…Indeed, disruption of the light/dark cycle during pregnancy has been associated with adverse outcomes, such as a higher risk of pre-term birth, low birth weight babies, spontaneous abortion and subfertility (Knutsson 2003;Mahoney 2010). Recent animal studies have shown that exposure to continuous light during pregnancy is a good model for development of neuropsychiatric disorders and developmental alterations such as cardiovascular dysfunction and skeletal defects in the offspring (Fontanetti et al 2014;Galdames et al 2014;Voiculescu et al 2016). However, under continuous light, the circadian clock is free running, and the question remains open to what extent the circadian system is disturbed by chronic stress, rather than CRD.…”