Perinatal Vitamin D Deficiency Enhances Brown Adipose Tissue Thermogenesis in Weanling Rats

Perinatal vitamin D (Vit. D) deficiency (VDD) disrupts the development of key tissues involved in metabolic regulation, including the endocrine pancreas, white adipose tissue, and skeletal muscle. Brown adipose tissue (BAT), essential for thermoregulation and energy homeostasis, may also be affected, but the impact of perinatal VDD on BAT physiology remains unclear. In this study, forty female Wistar rats were fed either a standard AIN93G diet (1000 IU Vit. D₃/kg; control group, CT) (<i>n</i> = 20) or a modified AIN93G diet lacking Vit. D (VDD group) (<i>n</i> = 20) for six weeks prior to conception and throughout gestation and lactation. Male offspring were evaluated at weaning (PN21) and adulthood (PN180) after Vit. D status was normalized through a standard diet. We found that perinatal VDD reduced total lipid droplet area, increased oxygen consumption, and upregulated thermogenic gene expression in BAT at weaning. Correspondingly, VDD offspring exhibited greater cold tolerance and enhanced BAT recruitment upon cold exposure (4 °C). Notably, normalization of Vit. D status by adulthood fully reversed these changes, indicating that while perinatal VDD transiently enhances BAT thermogenic activity during early life, it does not produce lasting effects into adulthood.