Olive oil-rich diet during pregnancy/lactation attenuated the early life stress effects on depressive-like behavior and altered energy metabolism in the dorsal hippocampus in a sex-specific manner

Abstract Early life is an important period for the development of the nervous system and for the programming of behavioural phenotypes in adulthood. In our study, two types of early-life stress were used: prolonged separation of pups from their mothers (for 3 h/day, maternal separation (MS)) and brief separation (for 15 min/day, handling (HD)). We analysed the effects of early-life stress on behaviour and the expression of HPA-associated genes in the hypothalamus, hippocampus, and frontal cortex of male mice. Adult mice in the MS group demonstrated reduced locomotor activity and deficiencies in spatial long-term memory, while the HD showed no significant changes. Additionally, early-life MS resulted in reduced hippocampal Crhr1 mRNA, increased MR/GR mRNA in the hippocampus and hypothalamus. Both groups, HD and MS, showed increased Avp mRNA in the hypothalamus. Thus, prolonged maternal separation but not brief leads to adverse behavioural changes and influences the expression of HPA-associated genes in a brain region-specific manner.

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Deficits in hippocampal-dependent memory across different rodent models of early life stress: systematic review and meta-analysis

Translational Psychiatry ◽

10.1038/s41398-021-01352-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mariana Rocha ◽

Daniel Wang ◽

Victor Avila-Quintero ◽

Michael H. Bloch ◽

Arie Kaffman

Keyword(s):

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Dorsal Hippocampus ◽

Meta Analysis ◽

Early Life Stress ◽

Ventral Hippocampus ◽

Contextual Fear Conditioning ◽

Rodent Models ◽

Improved Performance

AbstractExposure to early life stress (ELS) causes abnormal hippocampal development and functional deficits in rodents and humans, but no meta-analysis has been used yet to quantify the effects of different rodent models of ELS on hippocampal-dependent memory. We searched PubMed and Web of Science for publications that assessed the effects of handling, maternal separation (MS), and limited bedding and nesting (LBN) on performance in the Morris water maze (MWM), novel object recognition (NOR), and contextual fear conditioning (CFC). Forty-five studies met inclusion criteria (n = 451–763 rodents per test) and were used to calculate standardized mean differences (Hedge’s g) and to assess heterogeneity, publication bias, and the moderating effects of sex and species (rats vs. mice). We found significantly lower heterogeneity in LBN compared to handling and MS with no consistent effects of sex or species across the three paradigms. LBN and MS caused similar cognitive deficits in tasks that rely heavily on the dorsal hippocampus, such as MWM and NOR, and were significantly different compared to the improved performance seen in rodents exposed to handling. In the CFC task, which relies more on the ventral hippocampus, all three paradigms showed reduced freezing with moderate effect sizes that were not statistically different. These findings demonstrate the utility of using meta-analysis to quantify outcomes in a large number of inconsistent preclinical studies and highlight the need to further investigate the possibility that handling causes different alterations in the dorsal hippocampus but similar outcomes in the ventral hippocampus when compared to MS and LBN.

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