Vitamin D Deficiency Induction in Rats

Ten male Wistar rats (Harlan CPB, Horst, Netherlands), aged 9-10 weeks, weighing 300–325 grams at the beginning of the study were used. The rats underwent one-week acclimatization to the animal facility prior to the induction of vitamin D deficiency. Animals were maintained under conventional housing conditions and were given food and water ad libitum. From day one of the experiment, the rats were fed a vitamin D deficient diet (TD.87095 Brown C.C. Vit.D Defic, containing 20% lactose, 2% Ca, and 1.25% P). To induce CYP24A1 expression, to accelerate the catabolism of endogenous 25D and calcitriol stores, the rats received intraperitoneal injections of 32 ng of 19-nor-1,25-dihydroxyvitamin D2 (paricalcitol; Zemplar, kindly provided by AbbVie) on days 1, 3, 5, 8, 10, and 12. The rats were weighed on days 1, 10, 15, and 22 during the induction of vitamin D deficiency. Food consumption was measured every day. The experimental protocol was approved by the Animal Care Committee at the VU University Medical Center, Amsterdam.