Supraphysiological Doses of Vitamin A Promote Changes in Hippocampal Oscillation Bands and Cardiac Activity in Wistar...

Vitamin A is an essential micronutrient involved in growth, immune regulation, and central nervous system function; however, excessive intake may disrupt systemic homeostasis. This study investigated the electrophysiological effects of experimental hypervitaminosis A on hippocampal activity and cardiac function in male Wistar rats. Animals received a supraphysiological dose of vitamin A (50,000 IU/kg, intraperitoneally) once daily for 3, 7, or 14 days. Serum calcium levels were quantified, and electrophysiological recordings were obtained from the CA1 hippocampal region (EEG) and through electrocardiography (ECG). Vitamin A administration produced a time-dependent increase in total hippocampal spectral power. Power elevations were observed across multiple frequency bands, particularly theta (4-8 Hz), α (8-12 Hz), β (12-28 Hz), and γ (28-40 Hz) oscillations after 7 and 14 days of exposure. Serum calcium levels showed modest increases but remained within physiological reference ranges. Cardiac assessment revealed increased heart rate accompanied by reductions in R-R and QT intervals while maintaining sinus rhythm and preserved ECG morphology. These findings demonstrate that short-term exposure to supraphysiological vitamin A levels alters hippocampal oscillatory dynamics and modulates cardiac electrophysiological parameters in rats. Although the functional and mechanistic implications require further investigation, the results indicate that excessive vitamin A intake can influence neurocardiac electrophysiological homeostasis even in the absence of overt hypercalcemia.