Chrysin (5,7-dihydroxyflavone) is a flavonoid isolated from plants, such as Passiflora coerulea, Passiflora incarnata, and Matricaria chamomilla. This natural molecule exerts diverse pharmacological effects, which includes antioxidant, anti-inflammatory, anti-cancer, neuroprotective, and anti-apoptotic effects. Additionally, in brain structures, such as the hippocampus, prefrontal cortex, raphe nucleus, and striatum, involved in the physiopathology of anxiety and depression disorders, several neuropharmacological activities, including the activation of neurotransmitter systems (GABAergic, serotonergic, dopaminergic, and noradrenergic), neurotrophic factors, such as brain-derived neurotrophic factor and the nerve growth factor, and some signaling pathways are affected. The results showed that the anxiolytic and antidepressant-like effects of chrysin occurs through its interaction with specific neurotransmitter systems, principally the GABAergic and the serotonergic, and activation of other neurotrophic factors. However, it is not possible to discard the antioxidant and anti-inflammatory activities of chrysin while producing its anxiolytic- and antidepressant-like effects. Although these results have been obtained principally from pre-clinical research, they consistently demonstrate the potential therapeutic use of flavonoid chrysin as an anxiolytic and antidepressant agent. Therefore, this flavonoid could be considered as a promising novel therapy for anxiety and depression disorders.

Introduction. In rats, long-term ovariectomy results in low concentrations of steroid hormones and reproduces anxiety- and depression-like behavior after surgical menopause in women. Progesterone produces antidepressant-like effects two weeks post-ovariectomy (i.e., early post-ovariectomy) through actions on γ-aminobutyric acid-A (GABAA) receptors, but its antidepressant-like effects and mechanism of action in rats eight weeks post-ovariectomy (i.e., late post-ovariectomy, considered a model of surgical menopause) remain unknown. Objective. To explore the antidepressant-like effects of progesterone and the participation of GABAA receptors in rats eight weeks post-ovariectomy. Method. Long-term ovariectomized female Wistar rats were treated sub-acutely with vehicle or progesterone (.5, 1, and 2 mg/kg) and subjected to the open field and forced swim tests, and behavior was compared with cycling or fluoxetine-treated rats. The rats were then pretreated with picrotoxin (1 mg/kg) followed by progesterone (1 mg/kg) to explore the role of GABAA receptors in long-term-induced depression-like behavior. Results. Long-term ovariectomized rats exhibited depression-like behavior in the forced swim test compared with intact rats, an effect that was not observed in progesterone- and fluoxetine-treated long-term ovariectomized rats. These effects were not attributable to psychomotor alterations. In the open field test, the time spent rearing and grooming was lower in ovariectomized rats compared with intact rats, which was not observed in progesterone- and fluoxetine-treated rats. Picrotoxin blocked the effects of progesterone in both behavioral tests. Discussion and conclusion. These results indicated that sub-acute progesterone treatment reduced depression-like behavior through actions on GABAA receptors in a rat model of surgical menopause.

Women have a high susceptibility to the negative effects of stress. Hormonal changes experienced throughout their reproductive life partially contribute to a higher incidence of anxiety and depression symptoms, particularly, during natural or surgical menopause. In preclinical research, the flavonoid chrysin (5,7-dihydroxyflavone) exerts anxiolytic- and anti-despair-like effects; however, it is unknown whether chrysin exerts a protective effect against the behavioral changes produced by acute stress on locomotor activity and behavioral despair in rats at 12-weeks post-ovariectomy. Ovariectomized female Wistar rats were assigned to eight groups: vehicle group (10% DMSO), three groups with chrysin and three groups with the same dose of allopregnanolone (0.5, 1, and 2 mg/kg), and one group with diazepam (2 mg/kg). The treatments were administered for seven consecutive days and the effects were evaluated in the locomotor activity and swimming tests. Chrysin (2 mg/kg) increased the latency to first immobility and decreased the total immobility time in the swimming test as the reference drugs allopregnanolone and diazepam (2 mg/kg); while locomotor activity prevented the behavioral changes produced by swimming. In conclusion, chrysin exerts a protective effect against the behavioral changes induced by acute stress, similarly to the neurosteroid allopregnanolone and the benzodiazepine diazepam in rats subjected to a surgical menopause model.

Background: Premenstrual syndrome is characterized by emotional changes, including anxiety and depression symptoms, which may be treated with anxiolytic and antidepressant drugs, as well as estrogen therapy. However, steroidal estrogen therapy is contraindicated for patients with a potential risk of developing estrogen-dependent cancers through interactions with estrogen receptor α (ERα). Alternatively, genistein produces estrogenic effects in animals and humans at dietary dosages that act on the nuclear and membrane ERα, estrogen receptor β (ERβ), and the G-protein-coupled estrogen receptor (GPER). These receptors are likely involved in the anxiety symptoms observed in premenstrual disorders. The objective of this study was to evaluate the effects of genistein and 17β-estradiol on anxiety-like behavior and the plasma concentrations of estradiol and progesterone throughout the ovarian cycle of Wistar rats. Methods: The effect of the administration of 0.09 mg/kg of genistein or 17β-estradiol was evaluated using the elevated plus maze (EPM) test, locomotor activity test (LAT), and light/dark box (LDB) test, as well as by assessing the plasma concentrations of estradiol and progesterone, while considering the ovarian cycle phases. Results: Higher levels of anxiety-like behavior were detected in the metestrus–diestrus phase compared to the proestrus–estrus phase, which was associated with low concentrations of estradiol. Genistein, similarly to 17β-estradiol, significantly reduced anxiety-like behaviors in the EPM and LDB; however, 17β-estradiol, but not genistein, significantly increased the plasma estradiol concentration. No significant changes were found in locomotor activity or the plasma progesterone concentrations due to the treatments. Conclusions: These findings suggest that genistein may be useful in the development of alternative therapies to reduce the anxiety associated with low steroid hormone concentrations, which occur in premenstrual syndrome. Genistein could be an alternative to steroidal estrogen therapy to avoid potential side effects due to estradiol or antidepressant treatments, although it still requires medical care.

Ancient cultures have long studied plants for medicinal use. Today, multidisciplinary research focuses on re-evaluating these plants to discover drugs for treating various diseases, including psychiatric disorders. Pre-Columbian Mesoamerican cultures described three plants (Montanoa tomentosa, Montanoa frutescens, and Montanoa grandiflora) for treating both anxiety and depression disorders, which were called cihuapahtli in Nahuatl. This narrative review describes and analyzes the ethnobotanical use and phytochemical, pharmacological, behavioral, and toxicological effects of cihuapahtli, which can contribute to the discovery of anxiolytic and antidepressant drugs. The results show a significant advance in identifying bioactive phytochemicals, including triterpenes, diterpenes, monoterpenes, and sesquiterpenes, as well as sterols, flavonoids, and alkaloids. In particular, the mechanism of action underlying their anxiolytic and antidepressant effects involves the activation of oxytocinergic neurons in the paraventricular nucleus of the hypothalamus, as well as that of the GABAergic system by targeting GABA_A receptors. The three Montanoa species have the potential to help us develop anxiolytic and antidepressant drugs; however, future studies are still required to evaluate toxicity, dose standardization, possible variability in plant-derived compounds, pharmacokinetic parameters, and pharmacological interactions. Only then will preclinical evidence be sufficiently robust to justify translational studies evaluating the safety and efficacy of these plant extracts for the development of anxiolytic and antidepressant phytomedicines.