Effects of Artificial Ultraviolet Radiation on Serum 25-Hydroxyvitamin D₃ Concentrations in Captive Guinea Pigs (Cavia Porcellus)

Under natural conditions, guinea pigs (Cavia porcellus) are exposed to ultraviolet B (UVB) radiation. Although the role of UVB radiation in the photobiochemical synthesis of vitamin D is well documented in humans and other vertebrates, to date it has not been evaluated in guinea pigs. The purpose of this study was to determine whether artificial UVB radiation has an effect on serum 25-hydroxyvitamin D₃ levels in guinea pigs. A total of 12 juvenile guinea pigs were randomly assigned to 1 of 2 treatment groups: Group A was exposed to 12 hours of artificial UVB radiation (290 to 315nm) daily and Group B received ambient fluorescent light with no UVB supplementation for 12 hours/day. Blood samples were collected under anesthesia on days 0 and 18 to measure serum 25-hydroxyvitamin D₃ levels. Animals in both groups were offered the same diet. There was a significant difference in 25-hydroxyvitamin D₃ concentrations over time (F = 399.3, P = 0.0001) and by group (F = 63.6, P = 0.0001), with an average increase between sampling periods of 56.5nmol/L in Group A (UVB) and 2.33nmol/L in Group B (no UVB). This study represents the first attempt to measure the effect of UVB radiation on 25-hydroxyvitamin D₃ levels in guinea pigs. In vertebrates, vitamin D is an essential hormone that regulates many physiologic functions within the body. These preliminary findings confirm that guinea pigs can obtain vitamin D via photobiochemical synthesis, but additional work is needed to determine the physiologic importance of this finding and potential risks associated with UVB exposure in these rodents.