Multi-faceted Anti-obesity Effects of N-Methyl-D-Aspartate (NMDA) Receptor Modulators: Central-Peripheral Crosstalk.

Hypothalamus is central to food intake and satiety. Recent data unveiled the expression of N-methyl-D-aspartate receptors (NMDAR) on hypothalamic neurons and their interaction with GABAA and serotoninergic neuronal circuits. However, the precise mechanisms governing energy homeostasis remain elusive. Notably, in females, the consumption of progesterone-containing preparations, such as hormonal replacement therapy and birth control pills, has been associated with hyperphagia and obesity-effects mediated through the hypothalamus. To elucidate this phenomenon, we employed the progesterone-induced obesity model in female Swiss albino mice. Four NMDAR modulators were selected viz. dextromethorphan (Dxt), minocycline, d-aspartate, and cycloserine. Obesity was induced in female mice by progesterone administration for 4 weeks. Mice were allocated into 7 groups, group-1 as vehicle control (arachis oil), group-2 (progesterone + arachis oil), and group-3 as positive-control (progesterone + sibutramine); other groups were treated with test drugs + progesterone. Various parameters were recorded like food intake, thermogenesis, serum lipids, insulin, AST and ALT levels, organ-to-body weight ratio, total body fat, adiposity index, brain serotonin levels, histology of liver, kidney, and sizing of fat cells. Dxt-treated group has shown a significant downturn in body weight (p < 0.05) by a decline in food intake (p < 0.01), organ-to-liver ratio (p < 0.001), adiposity index (p < 0.01), and a rise in body temperature and brain serotonin level (p < 0.001). Dxt demonstrated anti-obesity effects by multiple mechanisms including interaction with hypothalamic GABAA channels and anti-inflammatory and free radical scavenging effects, improving the brain serotonin levels, and increasing insulin release from the pancreatic ß-cells.

Shugan Huoxue Huayu Fang attenuates carbon tetrachloride-induced hepatic fibrosis in rats by inhibiting transforming growth factor-ß1/Smad signaling.

OBJECTIVE: To investigate the potential mechanism by which Shugan Huoxue Huayu Fang (SGHXHYF) ameliorates liver fibrosis. METHODS: Liver fibrosis was induced in rats by intraperitoneal injection of carbon tetrachloride (CCl4) in peanut oil solution (40%, 3 mL/kg body weight) twice a week for 8 weeks. A normal control group received the same volume of peanut oil alone. During weeks 5-8, the CCl4-injected rat groups were administered saline (vehicle control), colchicine (0.1 mg/mL, 1 mg/kg, positive control), or SGHXHYF (0.1 mg/mL; 0.3, 0.6 and 1.2 mg/kg) once daily by oral gavage. Rats were sacrificed 24 h after the last treatment. Blood samples were collected for measurement of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), albumin (ALB), collagen Ⅰ and collagen Ⅲ levels. Liver samples were analyzed by histopathological staining, Masson's staining of extracellular matrix proteins, and immune-ohistochemical staining of αsmooth muscle actin (α-SMA). TGF-ß1/Smad protein and mRNA levels were analyzed by Western blot and quantitative reverse transcription-polymerase chain reaction analysis, respectively. In vitro experiments were also performed using rat hepatic stellate cells (HSCs). RESULTS: Compared with the control animals, CCl4-exposed rats exhibited elevated serum levels of ALT, AST, ALP, collagen I, and collagen III; reduced serum levels of ALB; and increased collagen deposition and αSMA expression in liver sections, reflecting liver fibrosis. CCl4 also increased expression of TGF-ß1 and the activated (phosphorylated) forms of Smad2 and Smad3 but reduced expression of the negative regulator Smad7 in the liver. Notably, concomitant administration of SGHXHYF to CCl4-exposed rats was found to significantly reverse or abolish the pro-fibrotic effects of CCl4 in the liver and reduced serum transferase levels. Analysis of HSCs in vitro confirmed that, mechanistically, SGHXHYF inhibited activation of the TGF-ß1/Smad signaling pathway by downregulating phosphorylated Smad2 and Smad3 and upregulating Smad7 levels. CONCLUSION: SGHXHYF ameliorated CCl4-induced liver fibrosis by inhibiting the TGF-ß1/Smad signaling pathway. These findings suggest that SGHXHYF may have clinical utility for the treatment or prevention of liver fibrosis.