Neuroprotective effects of vitamin D and 17ß-estradiol against ovariectomy-induced neuroinflammation and depressive-like state: Role of the AMPK/NF-κB pathway.

Estrogen replacement therapy (ERT) has been proven to relieve menopausal-related mental disorders including depression in postmenopausal women. However, the unsafety of ERT hinders its clinical use. In this study, we would evaluate whether vitamin D (VD), a hormone with optimal safety profile, could relieve the depressive-like symptom in ovariectomized (OVX) rats. Furthermore, we would determine whether vitamin D and 17ß-estradiol (E2) exert neurological function through their immunomodulatory effect in OVX rats. Middle-aged female SD rats were randomly divided into four groups, namely, control (SHAM), OVX, OVX + VD, and OVX + E2. Vitamin D (calcitriol, 100 ng/kg) and 17ß-estradiol (30 µg/kg) had been daily gavaged in the OVX + VD and OVX + E2 group, respectively. After 10-week administration, vitamin D and 17ß-estradiol both showed anti-depressive-like activity in the OVX rats. Using the method of immunofluorescent staining and western blot, vitamin D and 17ß-estradiol were demonstrated to upregulate each other's receptors, including VDR, ERα, and ERß in the hippocampus of OVX rats. Additionally, the upregulation of VDR, calbindin-D28k, and calbindin-D9k suggested that the vitamin D signaling system was amplified by vitamin D and 17ß-estradiol. Vitamin D and 17ß-estradiol showed neuroprotective effects by decreasing OVX-induced apoptosis and neuronal damage, regulating the AMPK/NF-κB signaling pathway, and reducing the proinflammatory cytokines (IL-1ß, IL-6, and TNFα), as well as iNOS and COX-2 in the hippocampus of OVX rats. Collectively, the present study demonstrated that vitamin D and 17ß-estradiol could upregulate each other's receptors and regulate the AMPK/NF-κB pathway to relieve the OVX-induced depressive-like state. The results could stimulate translational research towards the vitamin D potential for prevention or treatment of menopause-related depression.

Curcumin relieves depressive-like behaviors via inhibition of the NLRP3 inflammasome and kynurenine pathway in rats suffering from chronic unpredictable mild stress.

Increasing evidence suggests that inflammation is related to the pathophysiology of depression. Curcumin (CUR), which is a natural component extracted from the rhizome of Curcuma longa, seems to be efficacious in depression treatment. Hence, the present study aims to explore whether the anti-depressive effect of curcumin is connected to its anti-inflammatory features. Twenty-one SD rats were randomly divided into three groups, namely, control, CUMS (chronic unpredictable mild stress), and CUMS + CUR. After stress exposure for four weeks, the CUMS group showed depressive-like behaviors, and the curcumin treatment successfully corrected the depressive-like behaviors in stressed rats. Additionally, the curcumin could effectively decrease mRNA expression of proinflammatory cytokines (IL-1ß, IL-6, and TNF-α) and suppress NF-κB activation. Curcumin also inhibited the stressed-induced P2X7R/NLRP3 inflammasome axis activation, along with the reduced transformation of pro-IL-1ß to mature IL-1ß. The stress-induced activation of indolamine-2, 3-dioxygenase (IDO) and an increased kynurenine/tryptophan ratio were also ameliorated by curcumin supplementation. In conclusion, the study revealed that curcumin relieves a depressive-like state through the inhibition of the NLRP3 inflammasome and kynurenine pathway.

In vivo inhibitory effects of puerarin on selected rat cytochrome P450 isoenzymes.

Puerarin, the major bioactive constituent in kudzu root, is used widely in China for the treatment of cardiovascular diseases and diabetes. The purpose of this study was to find out whether puerarin influences the effect on rat cytochrome P450 (CYP) enzymes (CYP2B6, CYP2C9 and CYP3A4) by using cocktail probe drugs in vivo. A cocktail solution at a dose of 5 mL/kg, which contained bupropion (20 mg/kg), tolbutamide (5 mg/kg) and midazolam (20 mg/kg), was given as oral administration to rats treated with 10 days oral administration of puerarin. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The results showed that treatment with multiple doses of puerarin had inhibitory effects on rat CYP2B6, CYP2C9 and CYP3A4 enzyme activities. Therefore, caution is needed when puerarin is co-administered with CYP substrates, in view of herb-drug interactions.

Effect of myricetin on cytochrome P450 isoforms CYP1A2, CYP2C9 and CYP3A4 in rats.

Myricetin is one of the main ingredients of Chinese bayberry, which is used as a traditional medicine. The purpose of this study was to find out whether myricetin influences the rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9 and CYP3A4) by using cocktail probe drugs in vivo. A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg) and midazolam (10 mg/kg), was orally administered to rats treated for 14 days with myricetin. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0. Our study showed that treatment with multiple doses of myricetin had no effects on rat CYP1A2. However, CYP2C9 and CYP3A4 enzyme activities were inhibited after multiple doses of myricetin. Therefore, caution is needed when myricetin is co-administered with CYP2C9 or CYP3A4 substrates, which may result in herb-drug interactions.