Chronic Ultrasound Prenatal Stress Altered the Brain's Neurochemical Systems in Newborn Rats

Prenatal stress (PS) affects the development and functioning of the central nervous system, but the exact mechanisms underpinning this effect have not been pinpointed yet. A promising model of PS is one based on chronic exposure of pregnant rodents to variable-frequency ultrasound (US PS), as it mimics the PS with a psychic nature that most adequately captures the human stressors in modern society. The aim of this study was to investigate the effects of US PS on the brain neurotransmitter, neuropeptide, and neurotrophic systems of newborn Wistar rats. We determined the concentration of neurotransmitters and their metabolites (serotonin, HIAA, dopamine, DOPAC, and norepinephrine), neuropeptides (alpha-MSH, beta-endorphin, neurotensin, oxytocin, and substance P), and the neurotrophin brain-derived neurotrophic factor (BDNF) in rat brain tissues by HPLC-ED, ELISA, and multiplex ELISA. Correlation analysis and principal component analysis (PCA) were used to get a sense of the relationship between the biochemical parameters of the brain. The results demonstrated that US PS increases the concentration of serotonin (p=0.004) and DOPAC (p=0.04) in the hippocampus has no effect on the neurotransmitter systems of the frontal cortex, reduces the concentration of BDNF in the entirety of the brain of males (p=0.008), and increases the neuropeptides alpha-MSH (p=0.02), beta-endorphin (p=0.01), oxytocin (p=0.008), and substance P (p<0.001) in the entire brain. A degree of complexity in the neurotransmitter system network in the frontal cortex and network change in the hippocampus after exposure to US PS have been observed. PCA revealed a similar pattern of neurotransmitter system interactions in the frontal cortex and hippocampus in males and females after exposure to US PS. We suggest that US PS can alter neurodevelopment, which is mediated by changes in the studied neurochemical systems that thus affect the behavioral phenotype in animals.