A deficient pancreatic β-cell mass increases the risk of type 2 diabetes mellitus. Here, we investigated the effects of testosterone on the development of pancreatic β-cell mass in male rats. The β-cell mass of male rats castrated at 6 wk of age was reduced to ~30% of that of control rats at 16 wk of age, and castration caused glucose intolerance. Loss of β-cell mass occurred because of decreases in islet density per pancreas and β-cell cluster size. Castration was negatively associated with the number of Ki-67-positive β-cells and positively associated with the number of TUNEL-positive β-cells. These β-cell changes could be prevented by testosterone treatment. In contrast, castration did not affect β-cell mass in male mice. Androgen receptor (AR) localized differently in mouse and rat β-cells. Testosterone enhanced the viability of INS-1 and INS-1 #6, which expresses high levels of AR, in rat β-cell lines. siRNA-mediated AR knockdown or AR antagonism with hydroxyflutamide attenuated this enhancement. Moreover, testosterone did not stimulate INS-1 β-cell viability under high d-glucose conditions. In INS-1 β-cells, d-glucose dose dependently (5.5-22.2 mM) downregulated AR protein levels both in the presence and absence of testosterone. The intracellular calcium chelator (BAPTA-AM) could prevent this decrease in AR expression. AR levels were also reduced by a calcium ionophore (A23187), but not by insulin, in the absence of the proteasome inhibitor MG132. Our results indicate that testosterone regulates β-cell mass, at least in part, by AR activation in the β-cells of male rats and that the β-cell AR is degraded under hyperglycemic conditions.

SummaryFPA level, fibrinogen turnover rate, and fibrinolytic activity were studied on 18 patients with malignant disease. It was found that the FPA levels were significantly elevated and were correlated with fibrinogen turnover rate (r=0.74, p<0.001) and FDP (r = 0.58, p<0.02). Estimated FPA turnover rate was also correlated with fibrinogen turnover rate (r = 0.70, p<0.001). These results suggest that fibrinogen catabolism in patients with malignant disease is related with thrombin proteolysis. However, ratios of 1/2 FPA turnover rate to fibrinogen turnover rate suggest that intravascular thrombin proteolysis is not the major determinant of fibrinogen catabolism. It is suspected that extravascular thrombin proteolysis is responsible for the elevation of plasma FPA level which is correlated with acceleration of fibrinogen catabolism.

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We previously demonstrated that androgen signaling expands pancreatic β-cell mass in the sexual maturation period ( Am J Physiol Endocrinol Metab 314: E274–E286, 2018). The aim of this study was to elucidate whether fetal androgen signaling plays important roles in β-cell mass development and β-cell function in adulthood, defects of which are associated with type 2 diabetes mellitus. In the pancreas of male fetuses, androgen receptor (AR) was strongly expressed in the cytoplasm and at the cell membrane of Nkx6.1-positive β-cell precursor cells but was markedly reduced in insulin-positive β-cells. Administration of the anti-androgen flutamide to pregnant dams during late gestation reduced β-cell mass and Ki67-positive proliferating β-cells at birth in a male-specific manner without affecting body weight. The decrease of β-cell mass in flutamide-exposed male rats was not recovered when rats were fed a standard diet, whereas it was fully recovered when rats were fed a high-fat diet (HFD), at 6 and 12 wk of age. Flutamide exposure in utero led to the development of glucose intolerance in male rats due to a decrease in insulin secretion when fed HFD but not standard diet. Insulin sensitivity did not differ between the two groups irrespective of diet. These results indicated that the action of fetal androgen contributed to β-cell mass expansion in a sex-specific manner at birth and to the development of glucose intolerance by decreasing the secretion of insulin in HFD-fed male rats. Our data demonstrated the involvement of fetal androgen signaling in hypothesized sex differences in the developmental origins of health and disease by affecting pancreatic β-cell function.

Ferritin was purified from acute monocytic leukemia cells, and its biochemical and immunological properties were investigated. The iron content of acute monocytic leukemia cell ferritin was extremely low, and this ferritin migrated slightly faster than normal adult liver ferritin on immunoelectrophoresis and polyacrylamide gel disc electrophoresis. Isoelectric focusing in polyacrylamide gel showed predominantly acidic isoferritins. This was considered to characterize the nature of isoferritin from normal monocytes or to be the result of neoplastic change of monocytes. Immunologic studies failed to recognized any antigenic differences between isoferritin from acute monocytic leukemia cells and that from normal adult liver. Therefore, selective quantitation of acute monocytic leukemia cell isoferritin, if any in leukemic sera, by means of immunoassay was considered difficult.