Comparison of transitional vs surgical menopause on monoamine and amino acid levels in the rat brain.
Level 5 - mechanism / opinion, no new human data
Preclinical animal study
PubMed 29738870 · doi:10.1016/j.mce.2018.05.003
What was done
Adult rats underwent either surgical menopause via ovariectomy (OVX) or gradual transitional menopause via follicular depletion induced by daily injections of 4-vinylcyclohexene-diepoxide (VCD). Concentrations of monoamines, monoamine metabolites, tryptophan, and tyrosine were measured in the hippocampus, frontal cortex, and striatum at 1 and 6 weeks post-treatment and compared to gonadally intact rats sampled at proestrus and diestrus.
What was found
The abstract reports directional and statistical significance but no numerical values or effect sizes. In intact rats, frontal cortex serotonin was higher at proestrus than diestrus, and the 5-hydroxyindoleacetic acid (5-HIAA)/serotonin ratio in the frontal cortex and hippocampus was lower at proestrus. In both OVX and VCD groups, hippocampal norepinephrine, 5-HIAA, tryptophan, and tyrosine were significantly reduced at 1 week, but not at 6 weeks, relative to intact controls. Frontal cortex dopamine was elevated at 6 weeks post-OVX (with a similar trend at 1 week post-VCD). Striatal norepinephrine was elevated at 1 week post-OVX, whereas homovanillic acid was elevated at 1 week post-VCD.
Why it matters
This study shows that transitional and surgical loss of ovarian function lead to different neurochemical profiles over time across brain regions, emphasizing that experimental model choice is critical when investigating postmenopausal cognitive and neuroendocrine changes.
Limits
The abstract does not report sample sizes, exact concentrations, variance, or effect sizes. Findings derive entirely from a rodent model and cannot be directly translated to human menopausal neurobiology without clinical verification. Functional cognitive and behavioral outcomes were not measured.
Cited by
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