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The bile acid receptors, farnesoid X receptor (FXR) and Takeda G-protein-coupled receptor 5 (TGR5), regulate multiple pathways, including glucose and lipid metabolism. In a rabbit model of high-fat diet (HFD)-induced metabolic syndrome, long-term treatment with the dual FXR/TGR5 agonist INT-767 reduces visceral adipose tissue accumulation, hypercholesterolemia and nonalcoholic steatohepatitis. INT-767 significantly improves the hallmarks of insulin resistance in visceral adipose tissue (VAT) and induces mitochondrial and brown fat-specific markers. VAT preadipocytes isolated from INT-767-treated rabbits, compared to preadipocytes from HFD, show increased mRNA expression of brown adipogenesis markers. In addition, INT-767 induces improved mitochondrial ultrastructure and dynamic, reduced superoxide production and improved insulin signaling and lipid handling in preadipocytes. Both in vivo and in vitro treatments with INT-767 counteract, in preadipocytes, the HFD-induced alterations by upregulating genes related to mitochondrial biogenesis and function. In preadipocytes, INT-767 behaves mainly as a TGR5 agonist, directly activating dose dependently the cAMP/PKA pathway. However, in vitro experiments also suggest that FXR activation by INT-767 contributes to the insulin signaling improvement. INT-767 treatment counteracts HFD-induced liver histological alterations and normalizes the increased pro-inflammatory genes. INT-767 also induces a significant reduction of fatty acid synthesis and fibrosis markers, while increasing lipid handling, insulin signaling and mitochondrial markers. In conclusion, INT-767 significantly counteracts HFD-induced liver and fat alterations, restoring insulin sensitivity and prompting preadipocytes differentiation toward a metabolically healthy phenotype. [ABSTRACT FROM AUTHOR]

We recently demonstrated that testosterone dosing ameliorated the metabolic profile and reduced visceral adipose tissue (VAT) in a high-fat diet (HFD)-induced rabbit model of metabolic syndrome (MetS). We studied the effects of HFD and in vivo testosterone dosing on VAT function and the adipogenic capacity of rabbit preadipocytes isolated from VAT of regular diet (RD), HFD, and testosterone-treated HFD rabbits. VAT was studied by immunohistochemistry, western blot, andRT-PCR. Isolated rPADswere exposed to adipocyte differentiating mixture (DIM) to evaluate adipogenic potential. Adipocyte size was significantly increased in HFD VAT compared with RD, indicating adipocyte dysfunction, which was normalized by testosterone dosing. Accordingly, perilipin, an anti-lipolytic protein, was significantly increased in HFD VAT, when compared with other groups. HFD VAT was hypoxic, while testosterone dosing normalized VAT oxygenation. In VAT, androgen receptor expression was positively associated with mRNA expression of GLUT4 (SLC2A4) (insulin-regulated glucose transporter) and STAMP2 (STEAP4) (androgen-dependent gene required for insulin signaling). In testosterone-treated HFDVAT, STAMP2 mRNA was significantly increased when compared with the other groups. Moreover, GLUT4 membrane translocationwas significantly reduced in HFD VAT, compared with RD, and increased by testosterone. In DIM-exposed preadipocytes from HFD, triglyceride accumulation, adipocyte-specific genes, insulin-stimulated triglyceride synthesis, glucose uptake, and GLUT4 membrane translocation were reduced compared with preadipocytes from RD and normalized by in vivo testosterone dosing. In conclusion, testosterone dosing in a MetS animal model positively affects VAT functions. This could reflect the ability of testosterone in restoring insulin sensitivity in VAT, thus counteracting metabolic alterations. [ABSTRACT FROM AUTHOR]

Metabolic syndrome (MetS) and benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) are often associated. One of their common denominators is hypogonadism. However, testosterone supplementation is limited by concerns for potential prostatic side effects. The objective was to determine whether MetS-associated prostate alterations are prevented by testosterone supplementation. We used a previously described animal model of MetS, obtained by feeding male rabbits a high-fat diet (HFD) for 12 weeks. Subsets of HFD rabbits were treated with testosterone or with the farnesoid X receptor agonist INT-747. Rabbits fed a standard diet were used as controls. HFD-animals develop hypogonadism and all the MetS features: hyperglycemia, glucose intolerance, dyslipidemia, hypertension, and visceral obesity. In addition, HFD-animals show a prostate inflammation. Immunohistochemical analysis demonstrated that HFD-induced prostate fibrosis, hypoxia, and inflammation. The mRNA expression of several proinflammatory (IL8, IL6, IL1b, and TNFa), T lymphocyte (CD4, CD8, Tbet, Gata3, and ROR gt), macrophage (TLR2, TLR4, and STAMP2), neutrophil (lactoferrin), inflammation (COX2 and RAGE), and fibrosis/myofibroblast activation (TGFb, SM22a, aSMA, RhoA, and ROCK1/ROCK2) markers was significantly increased in HFD prostate. Testosterone, as well as INT-747, treatment prevented some MetS features, although only testosterone normalized all the HFD-induced prostate alterations. Interestingly, the ratio between testosterone and estradiol plasma level retains a significant, negative, association with all the fibrosis and the majority of inflammatory markers analyzed. These data highlight that testosterone protects rabbit prostate from MetS-induced prostatic hypoxia, fibrosis, and inflammation, which can play a role toward the development/progression of BPH/LUTS. [ABSTRACT FROM AUTHOR]

Metabolic Syndrome (MetS) is a cluster of clinical conditions, associated to an increased cardiovascular (CV) and metabolic risk along with hypogonadism (HG). Lifestyle modifications (including physical exercise, PhyEx) are well-known treatments for this condition [1]. We previously established a rabbit model of MetS that recapitulates the human phenotype, including HG [2]. We now report studies on the effects of PhyEx on hypothalamus-pituitary-testis (HPT) axis. MetS was induced in adult male rabbits fed a high-fat diet (HFD). Rabbits fed a regular diet were used as controls (RD). RD and HFD rabbits were exercise-trained to run on a treadmill for 12 weeks (RD + PhyEx and HFD+ PhyEx). HFD rabbits showed typical metabolic and CV features of MetS along with hypogonadotropic HG (reduced testosterone and LH plasma levels). Within the hypothalamus (preoptic region) a significant reduction of GnRH- and KISS1R-positive neurons, along with the increase of genes related to inflammation (COX2, IL6, CD68), glucose metabolism (GLUT1, GLUT4, IRS-1) and estrogen action (ERb, GPR30) was detected in HFD rabbit, as compared to RD group. Immunohistochemistry analysis confirmed the HFD-induced hypothalamic inflammation. Interestingly, genes encoding for inhibitory factors for GnRH, such as NPY, were also increased in HFD hypothalamus. Within the testis, HFD down-regulated LH receptor and all the steroidogenic enzymes leading to T synthesis. PhyEx completely restored T and LH plasma levels and GnRH/KISS1R immunostaining. All the aforementioned HDF-induced increase of inflammatory markers were significantly reduced in HFD+ PhyEx, with the exception of IL6. Moreover, at hypothalamic level, PhyEx decreased orexigenic and GnRH-inhibiting factors (dinorphin and its receptors OPRD1 and OPRK1), whereas increased anorexigenic ones (POMC). Within the testis, genes related to T formation (17ßHSD3) and metabolism (5a-reductase 1) were increased by PhyEx. In conclusion, in this experimental model, endurance training (PhyEx) completely reverted MetS-induced hypogonadotropic hypogonadism, exerting beneficial effects on the HPT axis. Particularly, in the hypothalamus PhysEX reduced HFD-induced inflammation. Hence, aerobic exercise training can be regarded an interesting strategy to combat MetS-associated alterations of the HPT axis. [ABSTRACT FROM AUTHOR]