Effects of ashwagandha (Withania somnifera) on zebrafish (Danio rerio) exposed to acute isolation and long-term crowding conditions

Background Ashwagandha ( Withania somnifera ) is an herbal supplement that has been utilized in traditional medicine systems for thousands of years. Chronic treatment with ashwagandha may have anti-anxiety potential; however, whether acute exposure to ashwagandha works to alleviate anxiety states has not been fully elucidated. In addition, more information is needed regarding the impact of housing conditions on stress responses in zebrafish ( Danio rerio ). In the current study, zebrafish exposed to social isolation, long-term crowding, or standard housing conditions were either acutely exposed (1 h) to ashwagandha extract (2.8 mg/L) or vehicle. Then, behavior was measured in the novel tank test and basal cortisol levels were measured. Results Housing conditions and ashwagandha exposure had subtle effects on behavior and cortisol levels. Acute isolation was associated with a reduction in motor activity, while long-term crowding did not impact behavior or basal hormone levels. Acute ashwagandha treatment elicited mild motor depressing effects and reduced basal cortisol levels. Conclusions This study adds to the growing body of literature regarding the impact of housing on stress responses in the zebrafish model and suggests that the herbal medicine ashwagandha may require longer or chronic exposure to significantly modulate anxiety-like behaviors and the neuroendocrine stress axis. Further studies are needed to investigate the timing of ashwagandha treatment on stress-related behaviors and hormone regulation.