Effects of lipopolysaccharide administration at different postnatal periods on behavioral and biochemical assessments in Wistar rats

Rodent model systems using lipopolysaccharide (LPS) administration have been developed to examine the effect of postnatal inflammation on neuropsychiatric behaviors. In this study, we investigated the effect of 250 μg/kg of LPS administration in male and female Wistar rats at three different postnatal periods. Rats were divided into four groups: a control group which received an intraperitoneal (IP) injection of phosphate buffer saline (PBS) on postnatal day 1 and three experimental groups which received an IP injection of LPS (250 μg/kg) at three different postnatal periods: day 1, day 3 and day 5. Each group consisted of 12 rats and had an equal gender distribution. At three months, rats were subjected to neurobehavioral assessments and biochemical oxidative and inflammatory assays. As a trend, LPS administration generates uniform anxiogenic behaviors, a depressive response, and increased central oxidative and inflammatory stress across all groups as compared to controls. Males receiving an LPS injection at postnatal days 1 and 3 and females receiving it at days 3 and 5 displayed more anxiogenic and depressive responses than their gender counterparts. Females had higher biomarker levels, with results being more pronounced in the group receiving injection on day 3. Postnatal LPS induces emotional disturbances along with oxidative stress and inflammation in brain tissues. Response to LPS injection seems to be gender-dependent and modulated by several variables, including its time of administration. Further investigations that take into consideration these variables, among others, are needed.