Oral calcium and vitamin D supplements differentially alter exploratory, anxiety-like behaviors and memory in male rats

Abstract

Oral calcium and calcium plus vitamin D supplements are commonly prescribed to several groups of patients, e.g., osteoporosis, fracture, and calcium deficiency. Adequate and steady extracellular calcium levels are essential for neuronal activity, whereas certain forms of calcium supplement (e.g., CaCO3) probably interfere with memory function. However, it was unclear whether a long-term use of ionized calcium (calcium chloride in drinking water ad libitum), vitamin D supplement (oral gavage) or the combination of both affected anxiety and memory, the latter of which was probably dependent on the hippocampal neurogenesis. Here, we aimed to determine the effects of calcium and/or vitamin D supplement on the anxiety- and memory-related behaviors and the expression of doublecortin (DCX), an indirect proxy indicator of hippocampal neurogenesis. Eight-week-old male Wistar rats were divided into 4 groups, i.e., control, calcium chloride-, 400 UI/kg vitamin D3-, and calcium chloride plus vitamin D-treated groups. After 4 weeks of treatment, anxiety-, exploration- and recognition memory-related behaviors were evaluated by elevated pulse-maze (EPM), open field test (OFT), and novel object recognition (NOR), respectively. The hippocampi were investigated for the expression of DCX protein by Western blot analysis. We found that oral calcium supplement increased exploratory behavior as evaluated by OFT and the recognition index in NOR test without any effect on anxiety behavior in EPM. On the other hand, vitamin D supplement was found to reduce anxiety-like behaviors. Significant upregulation of DCX protein expression was observed in the hippocampus of both calcium- and vitamin D-treated rats, suggesting their positive effects on neurogenesis. In conclusion, oral calcium and vitamin D supplements positively affected exploratory, anxiety-like behaviors and/or memory in male rats. Thus, they potentially benefit on mood and memory in osteoporotic patients beyond bone metabolism.

Assessing the Safety and Therapeutic Efficacy of Cannabidiol Lipid Nanoparticles in Alleviating Metabolic and Memory Impairments and Hippocampal Histopathological Changes in Diabetic Parkinson’s Rats

“…Further memory assessments, including spontaneous alternation in the Y maze and discrimination index in the NOR test, provided insight into cognitive function. As a result, vehicle-treated DP rats exhibited lower spontaneous alternation in the Y maze, increased exploration latency, and decreased discrimination index in the NOR test, which indicate memory impairment-like behaviors [ 30 , 31 , 32 , 68 ]. In contrast, treatment with CBD, CBD-LNP, or levodopa showed improvements in memory impairment-like behaviors.…”

“…The same rat was then placed back in the box and allowed to explore the new object for 3 min. A decrease in the discrimination ratio indicated cognitive and memory impairment [ 32 , 33 ]. The discrimination ratio was calculated using the following equation: …”

“…An increase in the number of rearing-stretch behaviors, which refers to the rat assuming an upright position, indicated increased exploration. The total number of lines crossed in the grid represented changes in locomotor activity [ 32 , 33 ].…”