Investigating brain-derived neurotrophic factor (BDNF) changes in three main rodent models of autism spectrum...

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social impairments, and repetitive and aggressive behaviors. The pathophysiology of ASD still remains unclear, while the population with ASD is 1/36 in children in the USA in 2024. Evidence suggests a wide range of inconsistent changes in brain-derived neurotrophic factor (BDNF), the most important neurotrophin in the central nervous system, in ASD. The present systematic review investigated studies that examined BDNF levels in three main ASD-like models in rodents [induced by valproic acid (VPA) and propionic acid (PPA), and in the BTBR mouse strain] in accord with PRISMA guidelines and in PubMed database. Forty-two studies were included. Most studies used male rats/mice. The results showed ASD model induced by VPA often leads to decreased BDNF, although unchanged or increased BDNF levels were also reported. ASD model induced by PPA leads to both increased and decreased BDNF. BDNF changes in BTBR mouse strain were also inconsistent. We found that the type of molecular assay appears to be important in evaluating BDNF. Also, few evidence showed a role for postnatal day and sex difference in BDNF changes in ASD-like rodent models. In addition, some studies have shown the potential role of the brain region in BDNF changes in different ASD-like models. In conclusion, it was suggested that inconsistencies in BDNF changes in rodent models of ASD may be related to the type of the molecular assay, the brain region, ASD model, sex, or even the postnatal day. However, evidence is still insufficient.