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Transitional versus surgical menopause in a rodent model: etiology of ovarian hormone loss impacts memory and the acetylcholine system.

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.

SUBMITTER: Acosta JI

PROVIDER: S-EPMC2736080 | biostudies-other | 2009 Sep

REPOSITORIES: biostudies-other

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Transitional versus surgical menopause in a rodent model: etiology of ovarian hormone loss impacts memory and the acetylcholine system.

Acosta Jazmin I JI Mayer Loretta L Talboom Joshua S JS Tsang Candy Wing S CW Smith Constance J CJ Enders Craig K CK Bimonte-Nelson Heather A HA

Endocrinology 20090521 9

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- ...[more]

PMID: 19470706

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Project description:Loss of ovarian function has important effects on neurotransmitter production and release with corresponding effects on cognitive performance. To date, there has been little direct comparison of the effects of surgical and transitional menopause on neurotransmitter pathways in the brain. In this study, effects on monoamines, monoamine metabolites, and the amino acids tryptophan (TRP) and tyrosine (TYR) were evaluated in adult ovariectomized (OVX) rats and in rats that underwent selective and gradual ovarian follicle depletion by daily injection of 4-vinylcyclohexene-diepoxide (VCD). Tissues from the hippocampus (HPC), frontal cortex (FCX), and striatum (STR) were dissected and analyzed at 1- and 6-weeks following OVX or VCD treatments. Tissues from gonadally intact rats were collected at proestrus and diestrus to represent neurochemical levels during natural states of high and low estrogens. In gonadally intact rats, higher levels of serotonin (5-HT) were detected at proestrus than at diestrus in the FCX. In addition, the ratio of 5-hydroxyindoleacetic acid (5-HIAA)/5HT in the FCX and HPC was lower at proestrus than at diestrus, suggesting an effect on 5-HT turnover in these regions. No other significant differences between proestrus and diestrus were observed. In OVX- and VCD-treated rats, changes were observed which were both brain region- and time point-dependent. In the HPC levels of norepinephrine, 5-HIAA, TRP and TYR were significantly reduced at 1 week, but not 6 weeks, in both OVX and VCD-treated rats relative to proestrus and diestrus. In the FCX, dopamine levels were elevated at 6 weeks after OVX relative to diestrus. A similar trend was observed at 1 week (but not 6 weeks) following VCD treatment. In the STR, norepinephrine levels were elevated at 1 week following OVX, and HVA levels were elevated at 1 week, but not 6 weeks, following VCD treatment, relative to proestrus and diestrus. Collectively, these data provide the first comprehensive analysis comparing the effects of two models of menopause on multiple neuroendocrine endpoints in the brain. These effects likely contribute to effects of surgical and transitional menopause on brain function and cognitive performance that have been reported.

Project description:ObjectiveOvarian suppression is recommended to complement endocrine therapy in premenopausal women with breast cancer and high-risk features. It can be achieved by either medical ovarian suppression or therapeutic bilateral salpingo-oophorectomy. Our objective was to evaluate characteristics of patients with stage I-III hormone receptor positive primary breast cancer who underwent bilateral salpingo-oophorectomy at our institution.Materials and methodsPremenopausal women with stage I-III hormone receptor positive primary breast cancer diagnosed between January 2010 and December 2014 were identified from a database. Patients with confirmed BRCA1/2 mutations were excluded. Distribution of characteristics between treatment groups was assessed using χ2 test and univariate logistic regression. A multivariate model was based on factors significant on univariate analysis.ResultsOf 2740 women identified, 2018 (74%) received endocrine treatment without ovarian ablation, 516 (19%) received endocrine treatment plus ovarian ablation, and 206 (7.5%) did not receive endocrine treatment. Among patients undergoing ovarian ablation 282/516 (55%) received medical ovarian suppression, while 234 (45%) underwent bilateral salpingo-oophorectomy. By univariate logistic analyses, predictors for ovarian ablation were younger age (OR 0.97), histology (other vs ductal: OR 0.23), lymph node involvement (OR 1.89), higher International Federation of Gynecology and Obstetrics (FIGO) stage (stage II vs I: OR 1.48; stage III vs I: OR 2.86), higher grade (grade 3 vs 1: OR 3.41; grade 2 vs 1: OR 2.99), chemotherapy (OR 1.52), and more recent year of diagnosis (2014 vs 2010; OR 1.713). Only year of diagnosis, stage, and human epidermal growth factor receptor 2 (HER-2) treatment remained significant in the multivariate model. Within the cohort undergoing ovarian ablation, older age (OR 1.05) was associated with therapeutic bilateral salpingo-oophorectomy. Of 234 undergoing bilateral salpingo-oophorectomy, 12 (5%) mild to moderate adverse surgical events were recorded.ConclusionsBilateral salpingo-oophorectomy is used frequently as an endocrine ablation strategy. Older age was associated with bilateral salpingo-oophorectomy. Perioperative morbidity was acceptable. Evaluation of long-term effects and quality of life associated with endocrine ablation will help guide patient/provider decision-making.

Dataset Information

Transitional versus surgical menopause in a rodent model: etiology of ovarian hormone loss impacts memory and the acetylcholine system.

Publications

Transitional versus surgical menopause in a rodent model: etiology of ovarian hormone loss impacts memory and the acetylcholine system.

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