P.2.039 - Effect of propionic acid on the rat’s behaviour: autism model

Abstract

Autism spectrum disorder (ASD) is a group of developmental disabilities that cause significant social, communication and behavioral challenges. ASD is characterized by deficits in social interactions, restrictive interests, repetitive behavior, impairments in language development/communication skills and emotional disorders [1]. The current prevalence of ASD is approximately 1 in 68 children [2]. Also, the prevalence is approximately 4- 5 times greater in males than in females [2]. There is a strong genetic component of ASD’s etiology; however, recently it has been shown that ASD can be exacerbated by several environmental factors. In accordance with this, the link between several dietary factors or gastrointestinal disturbances and ASD symptoms was described. Propionic Acid (PPA), a gut-derived compound, is one of such factors. Many studies indicate that PPA administration in experimental animals produces various alterations associated with human ASD; however, many questions related to the PPA model of ASD still need to be elucidated. In the present research, the changes in cognitive functions, social behavior and emotions of male, young adult Wistar rats (P45-60) were evaluated. The animals were treated intraperitoneally with PPA at a dose of 175 mg/kg diluted to 10 times in saline. The experimental groups were compared with control (untreated) ones using following behavioral tests: (i) Multi-branch maze–in order to assess the process of learning. The test was started 24 h after PPA injection. The time needed to cover the distance between starting point and cage and number of errors (numbers of entering the deadlock branches of the maze) was measured. (ii) Novel rat versus novel object-in order to evaluate changes in social behavior. The test was started 3 h after PPA injection. The number of physical contacts and total time spent together by two rats (one of them was held in cage) was measured. (iii) Crossed/T-maze–in order to evaluate the anxiety-related behavior. The experiments were performed 2, 24 and 48 h after PPA injections. The parameters: number/duration of episodes spent in the center of the maze, number of grooming episodes in open/closed branch of the maze, number of vertical standings in open/closed branch were studied. To compare the quantitative data obtained from control and experimental animals the 2-Sample t test was used. The P The Results revealed: (i) Compared to control, experimental rats need a significantly longer time for covering the distance between starting point and cage. There is no significant difference regarding errors. (ii) Compared to control, in the experimental group a significant decrease in the number of physical contacts between two rats was revealed. No significant difference in total time spent between two animals was detected. (iii) There is no significant difference between control and experimental animals in the above-mentioned parameters. Thus, a single injection of 175 mg/kg PPA induces alterations in learning and social behavior of young adult male rats, and produces no effect on some parameters of emotional behavior.