Perinatal exposure to synergistic multiple stressors leads to cellular and behavioral deficits mimicking Schizophrenia-like pathology.

Protein malnourishment and immune stress are potent perinatal stressors, encountered by children born under poor socioeconomic conditions. Thus, it is necessary to investigate how such stressors synergistically contribute towards developing neurological disorders in affected individuals. Pups from Wistar females, maintained on normal (high-protein, HP:20%) and low-protein (LP:8%) diets were used. Single and combined exposures of Poly I:C (viral mimetic: 5 mg/kg body weight) and Lipopolysaccharide (LPS; bacterial endotoxin: 0.3 mg/kg body weight) were injected to both HP and LP pups at postnatal days (PND) 3 and 9 respectively, creating eight groups: HP (control); HP+Poly I:C; HP+LPS; HP+Poly I:C+LPS; LP; LP+Poly I:C; LP+LPS; LP+Poly I:C+LPS (multi-hit). The effects of stressors on hippocampal cytoarchitecture and behavioral abilities were studied at PND 180. LP animals were found to be more vulnerable to immune stressors than HP animals and symptoms like neuronal damage, spine loss, downregulation of Egr 1 and Arc proteins, gliosis and behavioral deficits were maximum in the multi-hit group. Thus, from these findings it is outlined that cellular and behavioral changes that occur following multi-hit exposure may predispose individuals to developing Schizophrenia-like pathologies during adulthood.

Neuronal changes and cognitive deficits in a multi-hit rat model following cumulative impact of early life stressors.

Perinatal protein malnourishment (LP) is a leading cause for mental and physical retardation in children from poor socioeconomic conditions. Such malnourished children are vulnerable to additional stressors that may synergistically act to cause neurological disorders in adulthood. In this study, the above mentioned condition was mimicked via a multi-hit rat model in which pups born to LP mothers were co-injected with polyinosinic:polycytidylic acid (Poly I:C; viral mimetic) at postnatal day (PND) 3 and lipopolysaccharide (LPS; bacterial mimetic) at PND 9. Individual exposure of Poly I:C and LPS was also given to LP pups to correlate chronicity of stress. Similar treatments were also given to control pups. Hippocampal cellular apoptosis, ß III tubulin catastrophe, altered neuronal profiling and spatial memory impairments were assessed at PND 180, using specific immunohistochemical markers (active caspase 3, ß III tubulin, doublecortin), golgi studies and cognitive mazes (Morris water maze and T maze). Increase in cellular apoptosis, loss of dendritic arborization and spatial memory impairments were higher in the multi-hit group, than the single-hit groups. Such impairments observed due to multi-hit stress mimicked conditions similar to many neurological disorders and hence, it is hypothesized that later life neurological disorders might be an outcome of multiple early life hits.This article has an associated First Person interview with the first author of the paper.

Cumulative multiple early life hits- a potent threat leading to neurological disorders.

Early life Stress is a worldwide concern linked with development of later life neurological disorders. Early developmental age is sensitive to many prominent environmental insults like malnourishment, immune inflammation, abuse, maternal separation, alcohol and drugs. Hence, an individual during an early age encounters more than one simultaneous stressor that leads to impairment of cognitive and behavioral abilities, a symptom common to most of the neurological disorders. Stressors like malnourishment and immune inflammation are common and encountered by a huge number of populations, contributing enormously to a damaged CNS and in most of the cases they act synergistically in dependency to each other, giving rise to the concept of multi-hit. Multi perinatal hit acts by mimicking the mechanism of ageing in CNS and increasing the risk for later life neurological disorders. Multi stress exposure is also responsible for disrupting the cellular homeostasis of the brain by inducing glial activation, neurotoxicity and oxidative stress, which is the major reason of cell death and circuitry damage in brain. Multi perinatal hit thus increases the risk of neurological disorders by many folds through interfering with ongoing developmental cascades and eventually modulating the fate of cellular components in brain. Thus, a stress induced architecturally and chemically altered CNS is vulnerable and prone to neurological disorders like Alzheimer's, Schizophrenia, ALS, Autism and Parkinson's disease. This review compiles the information available regarding the effects of early life stressors on different components of brain, primarily focusing on the connection between perinatally encountered multi hit and development of later life neurological disorders.