Preliminary Data Regarding the Neurobehavioural Modulatory Effect of Acmella Oleracea L. Extract in an Zebrafish Model of Autism Spectrum Disorder

Abstract

Plant-derived extracts, such as those obtained from Acmella oleracea (L.) R.K. Jansen (AO), have drawn increasing interest due to possible neuroprotective properties. Several reports of neuroprotective potential were attributed to the main bioactive component of AO extract, spilanthol. Due to its capacity of spilanthol to cross the blood-brain barrier and to modulate serotonergic and GABAergic systems, AO extract may represent a promising experimental candidate for investigating effects on autism spectrum disorder (ASD) relevant behavioural symptoms, such as anxiety and aggression. The most common drug to model core symptoms of autism spectrum disorder (ASD) in zebrafish is the antiepileptic valproic acid (VPA). The current study aimed to evaluate the behavioural effects of AO extract in zebrafish, as compared to or in combination with VPA, to assess their effects on anxiety-like and aggressive behaviour, as assessed by the novel tank test (NTT) and the mirror-biting test (MBT). Our findings suggest that VPA-treated zebrafish show an increased frequency of aggressive and anxiety-like behaviours, as compared to controls. Similar anxiety-like, but not aggressive, behavioural changes were seen in AO-treated zebrafish. These effects may be connected with the modulation of GABAergic neurotransmission. Moreover, we observed that acute AO extract treatment was not able to modulate aggressive behaviour in VPA-treated or in healthy zebrafish.