Longdan Xiegan Tang attenuates liver injury and hepatic insulin resistance by regulating the angiotensin-converting enzyme 2/Ang (1-7)/Mas axis-mediated anti-inflammatory pathway in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: The ancient Chinese herbal formula Longdan Xiegan Tang (LXT, also called Gentiana Longdancao Decoction to Drain the Liver) treats insulin resistance- and inflammation-associated liver injuries in clinical practice. AIM OF THE STUDY: To investigate the molecular mechanisms underlying LXT-elicited improvement of the liver injuries. MATERIALS AND METHODS: Male rats were co-treated with olanzapine (5 mg/kg) and LXT extract (50 and 500 mg/kg) for eight weeks. Blood parameters were determined enzymatically or by ELISA. Gene/protein expression was analyzed by Real-Time PCR, Western blot and/or immunohistochemistry. RESULTS: LXT attenuated olanzapine-induced liver injury manifested by hyperactivities of plasma alanine aminotransferase and aspartate aminostransferase, hyperbilirubinemia and hypoalbuminemia. Furthermore, LXT improved hepatic insulin resistance that was indicated by hyperinsulinemia, the increased HOMA-IR index, and hepatic over-phosphorylation of Ser307 in insulin receptor substrate (IRS)1, Ser731 in IRS2, Tyr607 in phosphoinositide 3-kinase p85α and Ser473 in AKT at baseline. Mechanistically, LXT inhibited olanzapine-triggered hepatic over-phosphorylation of both IκB kinase (IKK)α/ß and nuclear factor (NF)κB p65 proteins, and mRNA overexpression of tumor necrosis factor α, interleukin 6, interleukin 1ß and CD68. More importantly, LXT restored the decreases in angiotensin-converting enzyme 2 (ACE2) protein level, and its downstream targets Ang (1-7) content and Mas receptor expression. CONCLUSIONS: The present results demonstrate that LXT attenuates liver injury and hepatic insulin resistance by regulating the ACE2/Ang (1-7)/Mas axis-mediated anti-inflammatory pathway in rats. Our findings provide a better understanding of LXT for treatment of insulin resistance- and inflammation-associated liver injuries.

Paeoniflorin ameliorates antipsychotic-induced hyperprolactinemia in rats by attenuating impairment of the dopamine D2 receptor and TGF-ß1 signaling pathways in the hypothalamus and pituitary.

ETHNOPHARMACOLOGICAL RELEVANCE: Paeoniflorin, a prominent component in some Chinese formulas for hyperprolactinemia-associated disorders, has been found to inhibit prolactin secretion in prolactinoma cells. AIM: To examine the efficacy of paeoniflorin on hyperprolactinemia and the underlying mechanisms of action. MATERIALS AND METHODS: Hyperprolactinemia in female rats was generated by administration of olanzapine (5 mg/kg, by a gavage method, once daily, × 13 weeks). The rats were co-treated with paeoniflorin (10 and 50 mg/kg). Prolactin and TGF-ß1 concentrations were detected by ELISA. Protein expression was determined by Western blot. The effect in MMQ cells was also examined. RESULTS: Paeoniflorin inhibited olanzapine-induced increases in plasma prolactin concentration and prolactin protein overexpression in the pituitary and hypothalamus of rats. Further, paeoniflorin restored olanzapine-induced downregulation of pituitary and hypothalamic dopamine D2 receptor (D2R) protein expression. More importantly, paeoniflorin attenuated olanzapine-suppressed protein expression of transforming growth factor (TGF)-ß1 and its downstream genes, type II TGF-ß receptor, type I TGF-ß receptor and phosphorylated SMAD3 in the tissues. However, paeoniflorin did not affect plasma TGF-ß1 concentration and hepatic TGF-ß1 protein expression. In accord, olanzapine-induced increase in prolactin concentration, upregulation of prolactin protein expression, and downregulation of protein expression of the D2R and TGF-ß1 signals in MMQ cells were attenuated. CONCLUSIONS: This study demonstrates that paeoniflorin ameliorates olanzapine-induced hyperprolactinemia in rats by attenuating impairment of the D2R and TGF-ß1 signaling pathways in the hypothalamus and pituitary. Our findings may provide evidence to support the use of paeoniflorin-contained Chinese herbs and formulas for hyperprolactinemia and its associated disorders.

The ancient Chinese formula Longdan Xiegan Tang improves antipsychotic-induced hyperprolactinemia by repairing the hypothalamic and pituitary TGF-ß1 signaling in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Antipsychotics often induce hyperprolactinemia. The transforming growth factor (TGF)-beta1 signaling in the pituitary and hypothalamus inhibits prolactin synthesis and secretion, and its impairment is implicated in neuropsychiatric disorders. Longdan Xiegan Tang (LXT) alone or together with antipsychotics have been used to treat various neuropsychiatric diseases and hyperprolactinemia-associated disorders. AIM OF THE STUDY: To investigate the effect of LXT on hyperprolactinemia and involvement of the TGF-beta1 signaling. MATERIALS AND METHODS: Male rats were co-administered with olanzapine (5 mg/kg) and LXT extract (50 and 500 mg/kg) (p.o., × 8 weeks). Plasma concentrations of prolactin and TGF-beta1 were determined by ELISA. Protein expression was analyzed by Western blot. RESULTS: Treatment of rats with LXT extract suppressed olanzapine-induced increase in plasma prolactin concentration and overexpression of pituitary and hypothalamic prolactin protein. Importantly, LXT restored olanzapine-induced decrease in protein expression of the key components of the TGF-beta1 signaling, TGF-beta1, type II TGF-beta receptor, type I TGF-beta receptor and phosphorylated SMAD3 in the pituitary and hypothalamus. Further, it antagonized downregulation of pituitary and hypothalamic dopamine D2 receptor (D2R) protein level, and inhibited pituitary estrogen receptor (ER) alpha and ERbeta protein expression. CONCLUSIONS: The present results suggest that LXT ameliorates antipsychotic-induced hyperprolactinemia in rats by repairing the pituitary and hypothalamic TGF-beta1 signaling possibly via D2R, ERs or/and other pathways. Our findings may also provide scientific elucidation for use of the ancient Chinese formula to treat the impaired TGF-beta1 signaling-associated neuropsychiatric disorders.