Species-specific control of hepatocyte growth factor expression and production in adipocytes in a differentiation-dependent manner

Hepatocyte growth factor (HGF) is a mesenchymal cell-derived factor that regulates cell growth, cell motility, and morphogenesis. Since there are conflicting reports on HGF-producing cells, we herein examined HGF activity in conditioned medium (CM) of bovine and mouse preadipocytes before and after adipogenic differentiation. CM of bovine adipocytes and mouse preadipocytes induced the morphogenesis of mammary epithelial cells that was inhibited by an NK4 HGF antagonist, whereas CM of bovine preadipocytes and mouse adipocytes did not. HGF mRNA expression was increased by a treatment with dexamethasone and isobutylmethylxanthine in bovine as well as human cells, whereas it was decreased in rodent cells. It was unfortunate that HGF gene promoter activity failed to reflect HGF mRNA expression in these cells. After actinomycin D treatment, expression of HGF mRNA remained stable in pre- and differentiated bovine adipocytes and mouse preadipocytes, whereas rapidly decreased in mouse-differentiated adipocytes. These results indicate that expression and production of HGF are regulated in a species-specific adipogenic differentiation-dependent manner and suggest that the decrease in HGF mRNA in mouse differentiated adipocytes is, at least in part, mediated by differentiation-dependent loss of its stability.

Overexpression of interferon-activated gene 202 (Ifi202) correlates with the progression of autoimmune glomerulonephritis associated with the MRL chromosome 1

B6.MRLc1(82-100) congenic mice carrying the telomeric region of lupus-prone MRL chromosome 1 develop autoimmune glomerulonephritis (GN). The GN susceptibility locus of B6.MRLc1(82-100) contains the interferon activated gene 200 (Ifi200) family, which consists of Ifi202, 203, 204, and 205. Recently, Ifi202 was suggested as a candidate gene for murine lupus. In this study, we assessed the association between Ifi200 family and GN in several disease models. We compared the expression of Ifi200 family members in 24 organs between the C57BL/6 and B6.MRLc1(82-100). The expressions of Ifi200 family members differed between strains, and the most dramatic differences appeared in Ifi202 expression. Briefly, in the blood, immune organs, lungs, and testes mRNA expression was higher in B6.MRLc1(82-100) mice. In the kidney and immune organs, only Ifi202 expression increased with the development of GN in B6.MRLc1(82-100), and significant differences from C57BL/6 were observed even before disease onset. Ifi202 expression in the kidneys of BXSB, NZB/WF1, and MRL/lpr was also significantly high in the early- and late-disease stages. Furthermore, laser microdissection-reverse-transcriptase-polymerase chain reaction analysis confirmed the high Ifi202 expression in all areas of B6.MRLc1(82-100) kidneys. In conclusion, in the Ifi200 family, Ifi202 expressions in the kidney and immune organs significantly increased with GN progression.

β3-Adrenoceptor agonist AJ-9677 reduces body fat in obese beagles

A selective beta3-adrenoceptor agonist, AJ-9677, was reported to ameliorate obesity and insulin resistance in KK-Ay mice. We examined the acute and chronic effects of AJ-9677 on obese dogs. Oral administration of AJ-9677 (0.01 or 0.1 mg/kg) to overnight fasted obese beagles produced a dose-dependent rise in the plasma levels of non-esterified fatty acids and insulin in 1h, followed by a gradual drop of the plasma glucose level. It produced no apparent abnormal behaviors, but easily detectable cutaneous flushing. Daily treatment of AJ-9677 at a lower dose (0.01 mg/kg) for three weeks produced no notable change in body weight, but at a higher dose (0.1 mg/kg) it reduced the body weight compared to a placebo treatment after seven weeks. Computed tomographic examinations revealed a remarkable reduction of body fat after the AJ treatment, being consistent with the histological observations that the adipose tissue of AJ-9677-treated dogs consisted of smaller and some multilocular adipocytes. The plasma levels of leptin and adiponectin were decreased and increased, respectively, after the AJ treatment, reflecting the reduction of adiposity. It was concluded that AJ-9677 is useful for the treatment of obesity in the dog.

Proinsulin C-peptide activates vagus efferent output in rats

The aim of this study was to examine the effect of proinsulin C-peptide on the autonomic nervous systems in rats. Intravenous administration of C-peptide gradually increased electrophysiological activity of the vagus nerves into the stomach and pancreas for at least 90 min. It also slightly increased gastric acid secretion that was suppressed by the treatment with atropine. Intraperitoneal injection of C-peptide did not affect the basal and stress-induced norepinephrine (NE) turnover rate, a biochemical index of sympathetic nerve activity. These results indicate that C-peptide increases parasympathetic nerve activity without affecting sympathetic nerve activity. This could explain, at least in part, the ameliorating effects of C-peptide on impaired cardiac autonomic nerve functions in patients with type 1 diabetes.