Neuroprotective effects of Clitoria ternatea L. against propionic acid-induced behavior and memory impairment in autistic rat model

Abstract

Autism spectrum disorder is primarily characterized by complex behavioral and altered memory as a consequence of neuronal development abnormalities. The treatment of autism is highly challenging because of the lack of knowledge about its exact etiopathology. In the Ayurvedic system of medicine, there are group of plants named ‘Medhya drugs' because of their ability to improve brain- and neuron-related activities like learning and memory. Clitoria ternatea L. is one of the listed ‘Medhya drugs’ which have been proved for its memory enhancement effects; in the present study, the ethanolic root extract of Clitoria ternatea L. was evaluated for its neuroprotective ability against propionic acid-induced memory and behavior impairments in an autistic rat model. The variation in behavior and memory were investigated by utilizing different procedures like rat elevated plus maze and novel object recognition test. In vitro assays for the estimations of glutamate and serotonin were also performed in isolated rat brain tissue homogenate. The object recognition and elevated plus maze test were showed the promising effects of Clitoria ternatea L. ethanolic root extract against the propionic acid-induced autism. In this study, the propionic acid infused rats (Group II) fail to recognize and explore the novel object compared to Group I (infused with phosphate-buffered saline) animals; extract treatment at two different doses (250 mg/kg and 500 mg/kg) (Groups III & IV, respectively) prevented these damage significantly (p < 0.001) so that extract-treated groups showed significant improvement in novel object recognition in a dose-dependent manner. Similarly, the effect of extract treatment on learning and memory of rats was investigated using transfer latency as a parameter for acquisition and retention of memory process on elevated plus maze; this further proved the memory enhancement ability of Clitoria ternatea L. Extract treatment also significantly reduced the concentration of different neurotransmitters like serotonin and glutamate in rat brain homogenate (Groups III &IV) in a dose-dependent manner as compared with the Group II. The ethanolic root extract of Clitoria ternatea L. proved to be effective against propionic acid-induced memory and behavior impairments in an autistic rat model.