Mechanisms in the in vivo release of lymphokines. V. Responses in alloxan-treated and genetically diabetic mice

Anti-diabetic and Hypolipidemic Effects of Aqueous-Extract from the Flower of Inula japonica in Alloxan-Induced Diabetic Mice

The anti-diabetic and hypolipidemic effects of aqueous-extract from the flower of Inula japonica (IJ) and its two fractions (IJR and IJP) were investigated in alloxan-induced diabetic mice. An oral glucose tolerance test (OGTT) of IJ was also performed in normal and diabetic mice. The results showed that IJ (1000 mg/kg), IJR (500 mg/kg) and IJP (250 mg/kg) significantly reduced blood glucose levels in diabetic mice by oral administration (p<0.01). IJ and IJP markedly decreased serum triglyceride concentrations (p<0.05) in diabetic mice. Their hypoglycemic activities were better than gliclazide (40 mg/kg) and compared with metformin (250 mg/kg). IJ raised plasma insulin levels in alloxan-induced diabetic mice. IJ, IJR and IJP significantly decreased the consumption of water and food in diabetic mice. OGTT showed that IJ slightly lowered blood glucose levels in normal mice, but significantly decreased blood glucose in diabetic mice between 60-150 min after a glucose load (p<0.05). The data indicated that IJ has both anti-diabetic and hypolipidemic effects.

T lymphopenia in obese diabetic (db/db) mice is non-selective and thymus independent

Although C57BL/KsJ db/db mice, an animal model of non-insulin-dependent diabetes mellitus (NIDDM), develop T lymphopenia in association with the progression of NIDDM, the T lymphopenia has not been fully investigated. In this study, to elucidate how and why T lymphopenia develops in db/db mice, T-lymphocyte subsets in spleen and thymus were longitudinally examined by flow cytometry and the effects of thymectomy and dietary restriction on the development of T lymphopenia were evaluated. After 8 weeks of age, when obese diabetes progresses, T lymphopenia in both spleen and thymus developed and all T-lymphocyte subsets examined were similarly reduced compared to lean (-/X) littermates, indicating non-selective T lymphopenia in db/db mice. Thymectomy performed at 5 wk of age, when neither T lymphopenia nor NIDDM yet presents, had no significant effect on the development of T lymphopenia. Furthermore, pair feeding until 30 weeks of age produced normal body weight and normoglycemia with still marked hyperinsulinemia, but failed to correct T lymphopenia in db/db mice. In conclusion, our results suggest that T lymphopenia may develop non-selectively and independently of either thymic dysfunction or obese diabetes in db/db mice.

Antidiabetic effects of interleukin 1

Interleukin 1 (IL-1), a cytokine released mainly by activated macrophages-monocytes, affects glucose homeostasis and may mediate some of the metabolic derangements observed during certain inflammatory and infectious processes. In this report, it is shown that IL-1 acts as a hypoglycemic agent not only in normal animals but also in mice at early stages of alloxan-induced diabetes and in genetically diabetic, insulin-resistant C57BL/Ks db/db mice and C57BL/6J ob/ob mice. In these animal models, a single injection of a low dose of human recombinant IL-1 normalized glucose blood levels for several hours. This effect was not mediated by possible insulin secretagogue actions of the cytokine. Furthermore, IL-1 markedly reduced the levels of triglycerides in blood of streptozotocin-induced diabetic mice at later stages of the disease. Although the final mechanism of action is at present unknown, the results showed that IL-1 is a hormone with powerful antidiabetic properties. Defective production of this cytokine associated with diabetes could contribute to aggravate the course of the disease during infectious and inflammatory processes.

Lymphocyte population dynamics in experimental murine diabetes

Hyperglycemia was induced in BALB/c mice with alloxan monohydrate. The spleen and lymph nodes of control vs. diabetic groups were analyzed for total cell content and the distribution of lymphocyte subpopulations when immunized 1) with DNFB, a contact allergen or 2) horse apoferritin, a protein antigen or 3) non-immunized at quiescence. The total cell contents of spleen and lymph nodes from diabetic groups, when stimulated with either antigen or at quiescence, were less than respective control groups. The distributions of B lymphocytes, T lymphocytes and suppressor T lymphocytes in the spleen and lymph nodes of diabetic mice at quiescence or during either immune response did not differ from controls. Diabetic mice produced more horse apoferritin-specific antibody in vivo than controls and lymphocytes from DNFB sensitized diabetic mice proliferated in vitro in response to DNBSO3. However, the proportion of proliferative lymphocytes in situ in diabetic DNFB-challenged mice was decreased in comparison to DNFB-challenged controls. From these data we conclude that hyperglycemia in alloxan diabetic mice non-specifically impedes, but does not completely inhibit, the proliferation and growth of lymphocyte populations.

Alterations in immunological function in streptozotocin-induced murine diabetes mellitus: correction by islet cell transplantation

Cell-mediated and humoral immune responses of streptozotocin-induced diabetic mice were evaluated using in vivo and in vitro immunological assays. C57BL/6 mice were rendered diabetic by a single intraperitoneal injection of 125-200 mg/kg of streptozotocin. Immunological studies were performed after the mice were diabetic (mean +/- SEM serum glucose 537 +/- 14 mg/dl) for a minimum of 4 weeks. Spleen cells from streptozotocin-induced diabetic mice exhibited significantly diminished direct IgM plaque-forming cell (PFC) responses following either in vivo or in vitro immunization with sheep erythrocytes, markedly impaired cytotoxic cell responses following in vivo or in vitro allogeneic stimulation, and diminished blastogenic response to the T-cell mitogens phytohemagglutinin and concanavalin A. In contrast the blastogenic response of diabetic spleen cells to lipopolysaccharide, a B-cell mitogen, was normal. The defects in in vivo PFC responses and in vivo cytotoxic cell responses were corrected by islet cell transplantation, suggesting that the abnormalities in immunological function of streptozotocin-induced diabetic mice are a consequence of the diabetic state and not of direct streptozotocin toxicity to lymphoid cells.