Physical enrichment enhances memory function by regulating stress hormone and brain acetylcholinesterase activity in rats exposed to restraint stress

Stress is a potent modulator of the mammalian brain. The highly conserved stress hormone response influences many brain regions, particularly the hippocampus, a region important for memory function. The effect of acute stress on the unique population of adult neural stem/progenitor cells (NPCs) that resides in the adult hippocampus is unclear. We found that acute stress increased hippocampal cell proliferation and astrocytic fibroblast growth factor 2 (FGF2) expression. The effect of acute stress occurred independent of basolateral amygdala neural input and was mimicked by treating isolated NPCs with conditioned media from corticosterone-treated primary astrocytes. Neutralization of FGF2 revealed that astrocyte-secreted FGF2 mediated stress-hormone-induced NPC proliferation. 2 weeks, but not 2 days, after acute stress, rats also showed enhanced fear extinction memory coincident with enhanced activation of newborn neurons. Our findings suggest a beneficial role for brief stress on the hippocampus and improve understanding of the adaptive capacity of the brain.

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Mustard Leaf Extract Suppresses Psychological Stress in Chronic Restraint Stress-Subjected Mice by Regulation of Stress Hormone, Neurotransmitters, and Apoptosis

Nutrients ◽

10.3390/nu12123640 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3640

Author(s):

Kyung-A. Hwang ◽

Hye-Jeong Hwang ◽

Yu Jin Hwang ◽

Young Jun Kim

Keyword(s):

Restraint Stress ◽

Leaf Extract ◽

Caspase 3 ◽

Chronic Restraint Stress ◽

Stress Hormone ◽

Induce Stress ◽

Bdnf Expression ◽

Stress Effects ◽

Cytokine Levels ◽

The Brain

Mustard leaf (Brassica juncea var. crispifolia L. H. Bailey) has been reported to have psychological properties such as anti-depressant activities. However, studies on chronic stress and depression caused by restraint have not been conducted. Therefore, this study aimed to evaluate the effects of a mustard leaf (ML) extract on chronic restraint stress (CRS) in mice. Male mice were subjected to a CRS protocol for a period of four weeks to induce stress. The results showed that the ML extract (100 and 500 mg/kg/perorally administered for four weeks) significantly decreased corticosterone levels and increased neurotransmitters levels in stressed mice. Apoptosis by CRS exposure was induced by Bcl-2 and Bax expression regulation and was suppressed by reducing caspase-3 and poly (ADP-ribose) polymerase expression after treatment with the ML extract. Our results confirmed that apoptosis was regulated by increased expression of brain-derived neurotrophic factor (BDNF). Additionally, cytokine levels were regulated by the ML extract. In conclusion, our results showed that the ML extract relieved stress effects by regulating hormones and neurotransmitters in CRS mice, BDNF expression, and apoptosis in the brain. Thus, it can be suggested that the studied ML extract is an agonist that can help relieve stress and depression.

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Transitional Versus Surgical Menopause in a Rodent Model: Etiology of Ovarian Hormone Loss Impacts Memory and the Acetylcholine System

Endocrinology ◽

10.1210/en.2008-1802 ◽

2009 ◽

Vol 150 (9) ◽

pp. 4248-4259 ◽

Cited By ~ 57

Author(s):

Jazmin I. Acosta ◽

Loretta Mayer ◽

Joshua S. Talboom ◽

Candy Wing S. Tsang ◽

Constance J. Smith ◽

...

Keyword(s):

Memory Task ◽

Acetylcholinesterase Activity ◽

Rodent Model ◽

Surgical Removal ◽

Ovarian Hormone ◽

Vinylcyclohexene Diepoxide ◽

Menopausal Women ◽

Surgical Menopause ◽

Negative Effect ◽

Brain Acetylcholinesterase

Abstract Clinical research suggests that type of ovarian hormone loss at menopause influences cognition. Until recently ovariectomy (OVX) has been the primary rodent model to examine effects of ovarian hormone loss on cognition. This model limits evaluations to abrupt and complete ovarian hormone loss, modeling less than 13% of women who receive surgical menopause. The majority of women do not have their ovaries surgically removed and undergo transitional hormone loss via ovarian follicular depletion. 4-Vinylcyclohexene-diepoxide (VCD) produces gradual ovarian follicular depletion in the rodent, with hormone profiles more similar to naturally menopausal women vs. OVX. We directly compared VCD and OVX models to examine whether type of hormone loss (transitional vs. surgical) impacted cognition as assessed on a maze battery as well as the cholinergic system tested via scopolamine mnemonic challenge and brain acetylcholinesterase activity. Middle-aged rats received either sham surgery, OVX surgery, VCD, or VCD then OVX to assess effects of removal of residual ovarian output after transitional menopause and follicular depletion. VCD-induced transitional menopause impaired learning of a spatial recent memory task; surgical removal of residual ovarian hormones by OVX abolished this negative effect of transitional menopause. Furthermore, transitional menopause before OVX was better for memory than an abrupt loss of hormones via OVX only. Surgical ovarian hormone loss, regardless of menopause history, increased hippocampal acetylcholinesterase activity. Circulating gonadotropin and androstenedione levels were related to cognitive competence. Collectively, findings suggest that in the rat, initiation of transitional menopause before surgical ovary removal can benefit mnemonic function and could obviate some negative cognitive consequences of surgical menopause alone.

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