The effects of vitamin D and zinc on anxiety and exploratory behaviours in rats

Vitamin D is a lipophilic vitamin. During the coronavirus pandemic, many people started taking Vitamin D (vit D) and zinc supplements to increase their immunity against the virus. However, there is no study investigating the effects of vitamin D and zinc on anxiety and exploratory behaviors. In this study, it is aimed to investigate the effect of different doses of vitamin D and zinc supplementation on anxiety and exploratory behavior in rats by open field test and elevated plus maze. In this study, 48 young (8 weeks old) male Wistar rats were equally divided into four groups. Normal water was given to Group 1 (sham group), 400 IU/day D vit to Group II, 1000 IU/day D vit to Group III, once a day for 8 weeks by gavage. 30 mg/kg ZnSO4 dissolved in physiological saline (ip) was administered to group IV for six days. After 8 weeks, vit D groups were given concomitant ZnSO4 (30 mg/kg, dissolved in saline, ip) and vit D (400 IU/day and 1000 IU/day, orally) for six days. At the end of this period, the rats underwent open field test (OFT) and elevated plus maze test (EPM). In the open field test, the number of entrances to the central area (NEC) of Group 2 (p<0.013) and Group 3 (p<0.003) and the time spent in the central area (STC) of Group 2 (p<0.039) and Group 3 (p<0.003) was lower than Group 1. The number of rearing (NR) values for Group 2 (p<0.000), Group 3 (p<0.000) and the number of defecation (ND) values of Group 2 (p<0.000), Group 3 (p<0.000) and Group 4 (p<0.004) were significantly lower than Group1. At EPM, Group 2 had the highest spent time in the closed area (STCA) value among all the groups. STCA value was statistically higher at Group 2 than Group 1 (p<0.01) and Group 4 (p<0.01), while spent time in the open area (STOA) value was statistically lower at Group 2 than Group 1 (p<0.04). Group 1 had the highest enter the open arm (EOA). EOA values for Group 2 (p<0.01) and Group 3 (p<0.03) were statistically lower than Group 1. According to our OFT and EPM results, anxiogenic effects were observed in rats given different doses of vitamin D and zinc; however, zinc did not affect anxiety when administered alone. We need more studies to investigate the effect of different doses of zinc on anxiety. Key Words: Vitamin D, Zinc, Anxiety, Exploratory Activity, Rat ` This study was supported by the Başkent University Research Board as a research project with the number DA20/17 and was approved by the Başkent University Clinical Research Ethics Committee with the decision number 20/15 on 02/11/2020.