Participation of estrogen receptors in the antidepressant-like effect of prolame on the forced swimming test

The intersection between menopause and depression: overview of research using animal models

Menopausal women may experience symptoms of depression, sometimes even progressing clinical depression requiring treatment to improve quality of life. While varying levels of estrogen in perimenopause may contribute to an increased biological vulnerability to mood disturbances, the effectiveness of estrogen replacement therapy (ERT) in the relief of depressive symptoms remains controversial. Menopausal depression has a complex, multifactorial etiology, that has limited the identification of optimal treatment strategies for the management of this psychiatric complaint. Nevertheless, clinical evidence increasingly supports the notion that estrogen exerts neuroprotective effects on brain structures related to mood regulation. Indeed, research using preclinical animal models continues to improve our understanding of menopause and the effectiveness of ERT and other substances at treating depression-like behaviors. However, questions regarding the efficacy of ERT in perimenopause have been raised. These questions may be answered by further investigation using specific animal models of reduced ovarian function. This review compares and discusses the advantages and pitfalls of different models emulating the menopausal stages and their relationship with the onset of depressive-like signs, as well as the efficacy and mechanisms of conventional and novel ERTs in treating depressive-like behavior. Ovariectomized young rats, middle-to-old aged intact rats, and females treated with reprotoxics have all been used as models of menopause, with stages ranging from surgical menopause to perimenopause. Additionally, this manuscript discusses the impact of organistic and therapeutic variables that may improve or reduce the antidepressant response of females to ERT. Findings from these models have revealed the complexity of the dynamic changes occurring in brain function during menopausal transition, reinforcing the idea that the best approach is timely intervention considering the opportunity window, in addition to the careful selection of treatment according to the presence or absence of reproductive tissue. Additionally, data from animal models has yielded evidence to support new promising estrogens that could be considered as ERTs with antidepressant properties and actions in endocrine situations in which traditional ERTs are not effective.

Prolame produces anxiolytic- and antidepressant-like effects in middle-aged female rats with less uterotrophic effects than 17β-estradiol

Estrogen hormone replacement therapy (EHRT), improving women's life quality at menopause, reduces anxiety and depression symptoms associated with ovarian hormonal decline. However, its potential adverse effects, like thromboembolism and cancer risk, limit its use. Prolame is a synthetic 17β-amino estrogen with antithrombotic actions that exerts anxiolytic- and antidepressant-like effects on young adult ovariectomized female rats. It is unknown if prolame's effects may be observed in age and endocrine conditions emulating menopause. This study aimed to identify the antidepressant- and anxiolytic-like effects of prolame and E2 (used as a reference estrogen treatment) in middle-aged female rats coursing with irregular cycles, in two different conditions: ovariectomized or gonadally intact. Results were compared with those from young adult ovariectomized rats. Prolame (60 or 120 μg/kg), 17β-estradiol (E2, 40 or 80 μg/kg), or vehicle were chronically administered, and their effects were evaluated in the elevated plus-maze, defensive burying behavior test, open field test, and forced swimming test. Uterotrophic actions were estimated by uterine weight related to body weight. Prolame and E2 produced robust anxiolytic- and antidepressant-like effects in young adult ovariectomized rats, but these effects were absent in gonadally intact middle-aged rats. Interestingly, only prolame induced anxiolytic- and antidepressant-like effects in middle-aged ovariectomized rats. Uterotrophic effects of prolame were weaker than E2 effects, notably in middle-aged females. Altogether, present data support the notion that prolame has the potential to be considered an EHRT with relevant psychoactive actions and with apparently lower adverse-side effects, especially in middle-aged populations.

Effects of post-ovariectomy time frame and age on the antidepressant-like actions of estradiol and prolame in female rats

Estrogen replacement therapy (ERT) is an effective treatment for symptoms associated with climacteric and depression some women experience during perimenopause and menopause. The antidepressant-like effects of ERT may depend on the type of estrogen, age, and time when restitution is initiated after hormonal decline. Prolame is a synthetic steroid with estrogenic and antidepressant-like effects that may produce fewer adverse effects. We hypothesize that such actions of prolame on females depend on age and the duration of hormone deprivation period. We assessed the antidepressant-like effects of 17β-estradiol (E₂) and prolame in young and middle-aged rats across different post-ovariectomy (Ovx) time frames. Independent groups of young adults and middle-aged female rats were tested in the forced swimming test (FST) at 3, 8, 16, and 24 weeks post-Ovx. Prolame and E₂ were administered in a sub-chronic schedule consisting of three injections before the FST. Likewise, the utero-trophic effects of these hormones were analyzed. We found that E₂ and prolame reduced immobility in young rats 3 and 8 weeks after Ovx; in contrast, only prolame produced this effect in middle-aged rats three weeks post-Ovx. E₂ and prolame increased the animals' utero-somatic index at all post-Ovx times, but the action of E₂ and prolame produced a greater response in young adult rats. Our findings showed that the antidepressant-like effects of E₂ and prolame depend on the post-Ovx time frame, age, and estrogen type. Interestingly, our results indicate that, in contrast to E₂, prolame maintained its antidepressant effect in middle-aged rats.

Potential Estrogenic Properties of 17β-Hydroxy-ethylimine Estradiol Derivative Targeted to Menopause Stage

BACKGROUND/AIM

Hormone replacement therapy during menopause increases the risk of thromboembolic diseases and cancer, so safety alternative therapeutic strategies are needed. 17β-Aminoestrogens are a synthetic estrogens group that possess mild anticoagulant activity that contrasts with the pro-coagulant effects showed by estradiol's (E₂) in rodents. Being considered an alternative to conventional hormone replacement therapy during menopause without thrombogenic risks producing. The present study aimed to determine the estrogenic profile and anxiolytic activity of 17β-[hydroxy-ethylimine]-1,3,5(10)-estratrien-3-ol (IE₂), a related compound unknown until now.

METHODS

IE₂ was assessed in immature rats by uterotrophic assay administering IE_2, E_2, or vehicle. In ovariectomized adult Wistar rats (Ovx) to facilitating the lordotic behavior compared with E_2, estradiol benzoate, or vehicle. The effect of IE₂ on anxiety was estimated in Ovx animals treated with IE₂, E₂, or vehicle group and evaluated in the elevated plus-maze model.

RESULTS AND CONCLUSION

IE₂ produced an uterotrophic effect, lordotic behavior, and anxiolytic effect in a dose-dependent manner, similar to E₂. IE₂ depicted estrogenicity, indicating potential clinical use as hormone replacement therapy during menopause.

Mirtazapine reduces the expression of cocaine-induced locomotor sensitization in male and female Wistar rats

BACKGROUND

Epidemiological studies have described that women are more vulnerable to the reinforcing effects of cocaine. In animals, the findings are similar: female rats show higher levels of cocaine self-administration and increased cocaine-induced locomotor activity. In contrast, women with depression respond better to treatment with antidepressants, however their therapeutic response to tetracyclic antidepressants is lower. Several studies have shown that mirtazapine-a tetracyclic antidepressant-decreases the behavioral effects of cocaine in male rats. The objective of this study was to evaluate the efficacy of daily dosing of mirtazapine on cocaine-induced locomotor activity and sensitization in naive female rats compared to male rats.

METHODS

Male and female Wistar rats were daily dosed with 10 mg/kg of cocaine. During extinction, cocaine was withdrawn and the groups received daily mirtazapine (30 mg/kg, i.p.) or saline. Tamoxifen was administered during the antagonism phase. After each administration, locomotor activity for each animal was recorded for 30 min in transparent Plexiglass activity chambers.

RESULTS

In this study, a higher cocaine locomotor response was found in females than in males and the mirtazapine was equally effective in decreasing cocaine-induced locomotor activity and the expression of locomotor sensitization in male and female rats. In addition, co-administration of mirtazapine and tamoxifen enhanced the efficacy of mirtazapine in female rats.

CONCLUSION

The results suggest that mirtazapine may be considered an effective therapeutic option for the treatment of cocaine use disorder in men and women.

Improvement in depression with oestrogen treatment in women with schizophrenia

Women with schizophrenia are often noted to suffer with comorbid depression. Many studies have shown associations between fluctuating oestrogen levels in the brain and mental illness. This study investigates the effect of oestradiol treatment on comorbid depressive symptoms in women with schizophrenia. This study is an 8-week, three-arm, double-blind, randomised-controlled trial. The 180 female participants were aged between 18 and 45, with schizophrenia and ongoing symptoms of psychosis Positive and Negative Syndrome Scale (PANSS) score > 60 despite a stable dose of antipsychotic medication. Depressive symptoms were assessed using Montgomery Asberg Depression Scale (MADRS) with a mean score of 73.77 at baseline. Participants received transdermal oestradiol 200 μg or transdermal oestradiol 100 μg or an identical placebo patch. The a priori outcome measure was the change in PANSS score measured at baseline and days 7, 14, 28 and 56, but in this study, we focused on the change in MADRS score at the same time points. Data were analysed by using Quade's rank analysis of covariance (ANCOVA) (Huitema 1980) with baseline MADRS score as a covariate. We found a fluctuating but overall trend towards improvement of comorbid depressive symptoms in women with schizophrenia taking transdermal oestrogen 200 mcg compared with oestrogen 100 mcg or placebo. The stronger 'antidepressant' effect of 200 mcg transdermal oestradiol was found at day 28 (p = 0.03). Our study suggests that adjunctive oestradiol treatment for depression may be a promising treatment for women with comorbid depression and schizophrenia.

Aqueous Extract of Pomegranate Alone or in Combination with Citalopram Produces Antidepressant-Like Effects in an Animal Model of Menopause: Participation of Estrogen Receptors

It has been reported that the aqueous extract of pomegranate (AE-PG) has polyphenols with estrogenic-like activities. The present work determines if AE-PG alone or in combination with the selective serotonin reuptake inhibitor, citalopram, has antidepressant-like effects. It was also analyzed the participation of estrogen receptors (ER). AE-PG (0.1, 1.0, 10, or 100 mg/kg) was evaluated in ovariectomized female Wistar rats subjected to the forced swimming test. The effects induced by AE-PG were compared with those of citalopram (2.5, 5.0, 10, and 20.0 mg/kg) and 17β-estradiol (E2; 2.5 5.0, and 10 μg/rat). Likewise, the combination of suboptimal doses of AE-PG (0.1 mg/kg) plus citalopram (2.5 mg/kg) was evaluated. To determine if ER participates in the antidepressant-like action of pomegranate, the estrogen antagonist tamoxifen (15 mg/kg) was administered with AE-PG (1 mg/kg). AE-PG produced antidepressant-like actions with a similar behavioral profile induced by citalopram and E2. Suboptimal doses of citalopram plus AE-PG produced antidepressant-like effects. Tamoxifen was able to block AE-PG's antidepressant-like actions. These results confirm the participation of ER in AE-PG's antidepressant-like effects. Furthermore, the additive effects observed with the combined treatment of AE-PG plus citalopram could be advantageous in the treatment of depressive disorders, such as menopause.

Ghrelin produces antidepressant-like effect in the estrogen deficient mice

Recent evidence shows that ghrelin plays an important role in depression. However, it was little known whether ghrelin produces antidepressant-like effect in the ovariectomized mice. The present study was aimed to investigate the antidepressant-like effects of the ghrelin in ovariectomized mice. In the forced swim test, ghrelin significantly decreased immobility time, reversing the “depressive-like” effect observed in ovariectomized mice, and this effect was reversed by the tamoxifen. In addition, immunohistochemical study indicated that ghrelin treatment reversed the reductions in c-Fos expression induced by ovariectomy. An estrogen antagonist tamoxifen also antagonized the effect of ghrelin on the c-Fos expression. Furthermore, the western blotting indicated that brain-derived neurotrophic factor (BDNF) in the hippocampus, but not phosphorylated cAMP response element-binding protein (pCREB)/CREB in the frontal cortex, were affected by ghrelin treatment. Ghrelin treatment significantly increased BrdU expression. Therefore, these findings suggest that ghrelin produces antidepressant-like effects in ovariectomized mice, and estrogen receptor may be involved in the antidepressant-like effects of the ghrelin.

Differential effect of the 17β-aminoestrogens prolame, butolame and pentolame in anxiety and depression models in rats

Estrogens of clinical use produce consistent antidepressant- and anxiolytic-like effects in animal models of menopause. Regulation of the hypothalamic-pituitary-adrenal (HPA) or stress axis, has been proposed as a pathway through which estrogens improve affective-like behaviors. Anticoagulant 17β-aminoestrogens (17β-AEs) butolame and pentolame mimic some effects of estradiol (E2), i.e., on female rodent sexual behavior, with opposite actions on coagulation. However, their psychoactive actions have not been explored. On the basis of similitude with E2's effects, we hypothesized that these 17β-AEs would induce anxiolytic- and antidepressant-like effects, which would be reflected in a reduction of activity in the HPA axis. In ovariectomized female rats, chronic treatment with prolame (60 μg/kg), butolame (65 μg/kg) and pentolame (70 μg/kg) reduced anxiety-like behavior in the elevated plus maze (evidenced by an increase in time in open arms, E2 (40 μg/kg) +176%; prolame +201%; butolame, +237%; and pentolame +295%, in comparison to the control vehicle group 100%). Pentolame also decreased significantly anxiety-like behavior in the burying behavior test. Prolame and E2 produced a significantly antidepressant-like action, which was not induced by butolame and pentolame. Behavioral effects of 17β-AEs (and E2) on anxiety and depression did not follow the same pattern than corticosterone or E2 levels; they also were associated to changes in locomotor activity, evaluated by the open field test. These results constitute the first evidence of specific and selective actions of butolame and pentolame as anxiolytics for females with a hypoestrogenic condition. Results also confirm the potential of prolame as an antidepressant steroid with equivalent actions to E2. Psychoactive properties of 17β-AEs in combinations with reduced adverse effects on coagulation, suggest that 17β-AEs may be a good alternative replacement therapy for women with symptoms associated with menopause.

17β-Aminoestrogens induce guinea pig airway smooth muscle hyperresponsiveness through L-type Ca(2+) channels activation

Therapy with estrogens is frequently used in menopausal women and as hormonal contraception. Because of its thrombotic effects, long term estrogen administration used in hormonal replacement therapy (HRT) and contraception could represent a health hazard. In this regard, 17β-aminoestrogens such as aminoestrol, butolame and pentolame have shown promising HRT potential, because they have a weak agonist estrogenic action and antithrombotic activity. Additionally, estrogens play a protective role in airway smooth muscle, but the effect of 17β-aminoestrogens on the airway smooth muscle has not been tested yet. In guinea pig tracheal smooth muscle pentolame and butolame induced hyperresponsiveness to histamine (His), carbachol (Cch) and KCl. Interestingly, aminoestrol did not show this effect at the highest concentration studied, it even lowered the contraction induced by Cch. The hyperresponsiveness induced by pentolame to His was abolished by nifedipine. In single tracheal myocytes, KCl induced an increment in the intracellular Ca(2+) concentration [Ca(2+)]i, pentolame also showed an increase in [Ca(2+)]i and the addition of KCl in the plateau of this rise further significantly augmented the [Ca(2+)]i response. Additionally, in patch clamp experiments pentolame increased the L-type Ca(2+) currents. Thus, 17β-aminoestrogens such as pentolame and butolame, but not aminoestrol, activate L-type Ca(2+) channel to induced hyperresponsiveness to Cch, His and KCl in guinea pig tracheal smooth muscle. Due to its lack of effect on airways and to its anticoagulant characteristics, aminoestrol seems to be the best alternative in the HRT among the 17β-aminoestrogens studied.