Simultaneous POMC gene transfer to hypothalamus and brainstem increases physical activity, lipolysis and reduces adult-onset obesity.

Pro-opiomelanocortin (POMC) neurons are identified in two brain sites, the arcuate nucleus of the hypothalamus and nucleus of the solitary tract (NTS) in brainstem. Earlier pharmacological and POMC gene transfer studies demonstrate that melanocortin activation in either site alone improves insulin sensitivity and reduces obesity. The present study, for the first time, investigated the long-term efficacy of POMC gene transfer concurrently into both sites in the regulation of energy metabolism in aged F344xBN rats bearing adult-onset obesity. Pair feeding was included to reveal food-independent POMC impact on energy expenditure. We introduced adeno-associated virus encoding either POMC or green fluorescence protein to the two brain areas in 22-month-old rats, then recorded food intake and body weight, assessed oxygen consumption, serum leptin, insulin and glucose, tested voluntary wheel running, analysed POMC expression, and examined fat metabolism in brown and white adipose tissues. POMC mRNA was significantly increased in both the hypothalamus and NTS region at termination. Relative to pair feeding, POMC caused sustained weight reduction and additional fat loss, lowered fasting insulin and glucose, and augmented white fat hormone-sensitive lipase activity and brown fat uncoupling protein 1 level. By wheel running assessment, the POMC animals ran twice the distance as the Control or pair-fed rats. Thus, the dual-site POMC treatment ameliorated adult-onset obesity effectively, involving a moderate hypophagia lasting ∼60 days, enhanced lipolysis and thermogenesis, and increased physical activity in the form of voluntary wheel running. The latter finding provides a clue for countering age-related decline in physical activity.

Testicular adrenal rest tumors in patients with congenital adrenal hyperplasia: 6 years of follow-up.

Background Testicular adrenal rest tumors (TARTs) leading to primary gonadal failure are the main etiology of infertility in congenital adrenal hyperplasia (CAH). We aimed at identifying the evolution of TART and related findings in young CAH patients. Methods Twelve male patients (3-23 years old) with 21-hydroxilase deficiency (11 with classic salt-wasting form) were included. Testicular ultrasonography (US) was performed in two moments, by a single blinded specialist in pediatric diagnostic imaging. Tumor progression was classified according to the Response Evaluation Criteria in Solid Tumors (RECIST). The clinical and laboratory data were retrieved from medical records. Serum 17-OH-progesterone (17OHP) and androstenedione concentrations were evaluated during the whole period of follow-up, from the CAH diagnosis. A logistic regression model with repeated measures was developed for the analysis. Results The prevalence of TART was 41.6% (n = 5) in the initial US evaluation and 66.6% (n = 8) after 6 years of follow-up. Tumor progression was detected in 4 of the 5 patients, and 1 presented with a stable tumor. Three patients presented with new tumors in the second evaluation. Most of the patients (n = 11) were pubertal, including a 7-year-old child with TART who presented with central precocious puberty. At regression analysis, it was observed that an inadequate hormonal control led to a 16 times greater chance of a patient to present with TART (OR = 16.08; confidence interval [CI] 95% = 2.38-108.81; p = 0.004). Conclusions We found a high prevalence of progressive TART in young pubertal subjects. US testicular screening should help in improving therapeutic optimization in CAH patients to reduce future impairment in fertility.

Melanocortin activation of nucleus of the solitary tract avoids anorectic tachyphylaxis and induces prolonged weight loss.

To examine the role of the brain stem melanocortin system in long-term energy regulation, we assessed the effects of overproduction of proopiomelanocortin (POMC) in the caudal brain stem of F344xBN rats with adult-onset obesity. Recombinant adeno-associated viral vector encoding POMC gene was delivered to the nucleus of solitary tract (NTS) in the hindbrain, and food intake, body weight, glucose and fat metabolism, brown adipose tissue thermogenesis, and mRNA levels of neuropeptides and melanocortin receptors were assessed. POMC delivery resulted in sustained reduction in food intake and body weight over 42 days and improved insulin sensitivity. At death, in recombinant adeno-associated viral vector-POMC-treated rats vs. control rats, alpha-melanocyte-stimulating hormone in NTS increased nearly 21-fold, whereas hypothalamic alpha-melanocyte-stimulating hormone remained unchanged. Visceral adiposity decreased by 37%; tissue triglyceride content diminished by 26% and 47% in liver and muscle, respectively; serum triglyceride and nonesterified fatty acids were reduced by 35% and 34%, respectively; phosphorylation of acetyl-CoA carboxylase was elevated by 63% in soleus muscle; brown adipose tissue uncoupling protein 1 increased by 30%; and melanocortin 3 receptor expression declined by 60%, whereas neuropeptide Y, agouti-related protein, and MC4 receptor mRNA levels were unchanged in the NTS. In conclusion, POMC overexpression in the NTS produces a characteristic unabated hypophagia that is uniquely different from the anorexic tachyphylaxis following POMC overexpression in the hypothalamus. The sustained anorectic response may result from absence of compensatory elements in the NTS, such as increased agouti-related protein expression, suggesting melanocortin activation of the brain stem may be a viable strategy to alleviate obesity.

Reprogramming liver-stem WB cells into functional insulin-producing cells by persistent expression of Pdx1- and Pdx1-VP16 mediated by lentiviral vectors.

Adenovirus-mediated transient expression of the pancreatic duodenal homeobox transcription factor Pdx1 in mouse liver activates pancreatic endocrine and exocrine genes, the latter reportedly resulting in severe hepatitis. Expression of a super-active form of Pdx1 or Pdx1-VP16 selectively transdifferentiates hepatic WB cells into functional pancreatic beta-like insulin-producing cells, without evidence of exocrine differentiation. No study has systematically compared the transdifferentiation efficiency of Pdx1 and Pdx1-VP16 at the cellular and molecular level. Comparisons can be ambiguous when vectors harboring a transcription factor cDNA have differing extents and duration of gene expression. In view of the remarkable capacity of lentiviral vector (LV) for delivering and integrating transgene into both dividing and nondividing cells, we transduced rat hepatic stem cell-like WB cells with LV-Pdx1 or LV-Pdx1-VP16, and then used the limiting-dilution technique to clone single-cell-derived cell lines that stably express either Pdx1 or Pdx1-VP16. With these cell lines, we studied: (a) the expression of Pdx1 or Pdx1-VP16 protein by Western blotting and immunocytochemistry; (b) the repertoire of long-term expression of Pdx1- or Pdx1-VP16-induced pancreatic gene expression using RT-PCR methods; and (c) their capacity to serve as beta-cell surrogates in restoring euglycemia in streptozotocin-treated diabetic mice. We found that cell lines expressing either Pdx1 or Pdx1-VP16 long-term exhibited similar profiles for expression of genes related to pancreatic development and beta-cell function, and reversed hyperglycemia in diabetic mice. We also examined short-term expression of Pdx1 or Pdx1-VP16, and the results demonstrated that expression of Pdx1-VP16 is more efficient in initiating liver-to-endocrine pancreas transdifferentiation. Our findings demonstrate: (a) that the LV system is highly effective in producing persistent expression of Pdx1 or Pdx1-VP16 in WB hepatic cells; and (b) long-term, persistent expression of either Pdx1 or Pdx1-VP16 is similarly effective in converting hepatic stem cells into pancreatic endocrine precursor cells that, upon transplantation into diabetic mice, become functional insulin-producing cells and restore euglycemia.