Biomedical subjects

B Chandrasekar

Publications and source records attributed to B Chandrasekar.

At least 55 records · Page 3Linked to original sources

PubMed1995

Dietary lipids and calorie restriction affect mammary tumor incidence and gene expression in mouse mammary tumor virus/v-Ha-ras transgenic mice.

We have studied the effects of food restriction (FR) and substitution of fish oil (FO; omega 3) for corn oil (CO; omega 6) on breast tumor incidence and survival in mouse mammary tumor virus/v-Ha-ras transgenic (Onco) mice. The diets were as follows: group 1, 5% (wt/wt) CO fed ad libitum (AL); group 2, 5% CO, restricted calories (40% fewer calories than AL; FR); group 3, 20% CO fed AL; and group 4, 20% FO fed AL. After 3 years, 40% of FR Onco (group 2) mice were alive, whereas there were no survivors in the other three groups. Similarly, tumor incidence was reduced to 27% (5 out of 18) in FR animals (group 2), whereas it was 83% (11 out of 13) in group 1 mice, 89% (16 out of 18) in group 3 mice, and 71% (10 out of 14) in group 4 mice. These protective effects of FR on survival and tumor incidence were paralleled by higher expression of the tumor suppressor gene p53 (wild type) and free-radical scavenging enzymes (catalase and superoxide dismutase) in breast tumors. Immunoblotting showed less ras gene product, p21, and increased p53 levels in the tumors of FR mice. In addition, FR decreased RNA levels of c-erbB-2, interleukin 6, and the transgene v-Ha-ras in tumors. In contrast, analysis of hepatic mRNA from tumor-bearing FR mice revealed higher expression of catalase, glutathione peroxidase, and superoxide dismutase. Survival and tumor incidence were not influenced significantly by dietary supplementation with FO in place of CO. Taken together, our studies suggest that moderate restriction of energy intake significantly inhibited the development of mammary tumors and altered expression of cytokines, oncogenes, and free-radical scavenging enzymes.

Animals↗

PubMed1995

Effects of calorie restriction on transforming growth factor beta 1 and proinflammatory cytokines in murine Sjogren's syndrome.

The present study was carried out to determine whether restricting dietary calories prevents salivary gland abnormalities and modulates expression of transforming growth factor beta and proinflammatory cytokines, IL-6, and TNF alpha in major salivary glands (SG) of autoimmune lupus-prone (NZB x NZW)F1 (B/W) female mice. These mice develop focal lymphocytic interstitial and periductal round cell infiltrates in salivary glands similar to those of humans with Sjogren's syndrome. Weanling B/W mice were fed a nutritionally adequate semipurified diet either ad libitum (AL) or a calorie-restricted (CR; 40% less calories than AL) diet. The mice were sacrificed at 3.5 months (young) and 8.5 months (old) of age. Histopathologic and histomorphometric analyses as well as growth factor and cytokine protein and mRNA expression were carried out in the SG. Histomorphometric analysis of SG from young mice showed no differences between AL and CR mice, but old AL (vs old CR) had a 7.3-fold higher focus score and a 34-fold increase in percentage area inflammation. mRNA analysis revealed significantly higher levels of TGF beta 1 in SG of old CR (6.8-fold) mice. In contrast, CR reduced mRNA expression of proinflammatory cytokines (IL-6, 2.9-fold for young and 4.8-fold for old; TNF alpha, old 3.9-fold). By immunoblotting, significantly higher levels of TGF beta 1 protein was detected in old CR mice (vs old AL; 13.2-fold). IL-6 and TNF alpha proteins were undetectable in both young and old CR groups, whereas an increase in IL-6 (4.7-fold) and TNF alpha (9.3-fold) was observed in old AL mice. These results indicate that amelioration of the histological severity of disease in SG of B/W mice is paralleled and possibly mediated by increased expression of immunosuppressive TGF beta 1 and decreased expression of proinflammatory cytokines.

Animals↗

PubMed1995

Dietary omega-3 lipids delay the onset and progression of autoimmune lupus nephritis by inhibiting transforming growth factor beta mRNA and protein expression.

The present study was carried out to test whether transforming growth factor beta (TGF beta) plays a pathological role in the induction or progression of glomerulonephritis in a murine model of systemic lupus erythematosus (SLE), and whether dietary supplementation with fish oil (FO) can modulate the expression of TGF beta. Weanling female (NZB x NZW) F1 (B/W) mice were divided into three groups. One group was fed an unmanipulated diet (lab. chow; LC) and the other two groups were fed a nutritionally adequate semipurified diet supplemented with 10% CO or FO. Both water and food were provided ad libitum. Proteinuria and serum anti-dsDNA antibody levels were measured to assess disease progression. Mice were killed at 3.5 and 6.5 months of age and renal mRNA levels for TGF beta isoforms, fibronectin-1 (FN-1) and intercellular adhesion molecule-1 (ICAM-1) were studied by Northern blot analysis. TGF beta 1 protein levels were also examined in kidneys by Western blot analysis. Our results indicate that at 3.5 months of age, when urinary protein levels were undetectable and very low levels of anti-dsDNA were detected, no mRNA signal could be detected for TGF beta isoforms, ICAM-1 and FN-1 in either dietary group. However, at 6.5 months, the FO-fed mice, compared to LC and CO, had [1] greatly reduced proteinuria (LC: 2-3+, CO: 2-3+; FO: trace -1+) and serum anti-dsDNA antibodies; [2] improved survival (CO: 100% death (15/15) occurred by 8 months; FO: 50% were alive at 12 months (8/15) and [3] reduced renal TGF beta 1 mRNA and protein levels. TGF beta 2 and beta 3 were not significantly affected by FO diet. Similarly, lower levels of renal FN-1 and ICAM-1 mRNA were observed in FO fed mice. These data indicate that in B/W mice on a FO diet, prolonged survival and amelioration of renal disease may be attributed at least in part to lower levels of TGF beta 1 mRNA and protein in the kidneys.

Adjuvants, Immunologic↗

PubMed1995

Calorie restriction modulates lymphocyte subset phenotype and increases apoptosis in MRL/lpr mice.

Defective expression of the Fas apoptotic gene may account for overproduction of CD4- CD8- B220+ cells (double-negative) in MRL/MpJ-lpr/lpr (lpr) mice. Previous studies have shown that calorie restriction (CR) inhibits the development of autoimmune disease and extends life span in these animals. The present studies describe the effects of CR on the distribution of lymphocyte phenotypes, lymphocyte proliferative response, and cytokine release. The effects of CR on dexamethasone (DEX)-induced apoptosis were also studied using propidium iodide (PI) uptake and DNA fragmentation in splenocytes and lymph node (LN) cells. Weanling female mice were fed a nutritionally adequate semipurified diet either ad libitum (AL) or with 40% fewer calories than AL (CR), and killed at 5 months of age. CR mice had fewer palpable lymph nodes, and decreased serum anti-dsDNA antibodies. Mitogen (ConA, anti-CD3, and LPS) and superantigen (SEB)-induced proliferative response was significantly lower in lymphoid cells from AL fed animals. FACS analysis of cells from CR animals showed decreased CD4- CD8- cells in spleen (1.7-fold, P < 0.025) and LN (1.6-fold P < 0.01) and significantly higher CD4+ (spleen, 1.7-fold, P < 0.0001; LN, 2.6-fold, P < 0.025) and CD8+ (spleen, 1.6-fold, P < 0.001; LN, 5.2-fold, P < 0.005) cells. ConA-stimulated IL-2 release was increased in CR animals (splenocytes, 7.5-fold, P < 0.001; LN cells, 6.1-fold, P < 0.01). Finally, apoptosis in response to Dex was increased in CR animals as indicated by the presence of more PI-positive cells (spleen, 15.8%; LN, 10.7%; P < 0.01) and increased DNA fragmentation. In summary, the amelioration of autoimmune disease in MRL/lpr mice by CR is accompanied by prevention of the rise in 'double-negative' T cells and by maintenance of lymphocyte responsiveness to mitogens and DEX-induced apoptosis at higher levels.

Animals↗

PubMed1995

Induction of transcription of "immediate early genes" by low-dose ionizing radiation.

The induction of transcription of specific genes after exposure to ionizing radiation has previously been reported after lethal doses of radiation (2-50 Gy). Little attention has been focused on expression of "immediate early genes" after low doses of ionizing radiation, where cell viability remains high. This dose range (0.25-2.0 Gy) is above the diagnostic dose level but at or below the doses typical for a single exposure in fractionated radiotherapy treatment of cancer. In this study, it was observed that doses in the range of 0.25-2.0 Gy induced different amounts of the mRNAs of the proto-oncogenes c-fos, c-jun, c-myc and c-Ha-ras at a given dose and time in Epstein-Barr virus-transformed human lymphoblastoid 244B cells. A maximum response was seen after a dose of 0.5 Gy for all but c-fos, which showed a maximum response after exposure to 0.25 Gy. Time-course studies demonstrated that, for all four proto-oncogenes, the induction was transient, reaching a maximum at 1 h and declining to the constitutive level at 4 h after irradiation. Using second-messenger specific inhibitors, the signaling pathways involved in the induction of these proto-oncogenes was also investigated. The results showed that all four of the proto-oncogenes induced after 0.5 Gy shared a common pathway of tyrosine kinase activation. Other signaling pathways included protein kinase C, reactive oxygen intermediates and calcium-dependent kinases; these were found to be differentially involved in the induction of transcription of the individual proto-oncogenes. In summary, this study suggests that low-dose ionizing radiation (0.25-2.0 Gy) can modulate expression of immediate early genes. Secondly, the activation of immediate early genes after low-dose exposure involves multiple second-messenger signaling pathways. Third, the magnitude of involvement of the different signaling pathways after low-dose radiation is different for each proto-oncogene expressed.

Cell Line, Transformed↗

PubMed1995

Effects of energy intake on type 1 plasminogen activator inhibitor levels in glomeruli of lupus-prone B/W mice.

Calorie restriction (CR) and/or reduced energy intake ameliorates the progression of autoimmune renal disease in (NZB x NZW)F1 (B/W) female mice and increases life span. Like other forms of glomerulonephritis, the lupus-like kidney disease observed in these animals is frequently accompanied by glomerular deposition of fibrin and increased accumulation of mesangial matrix. Because alterations in plasminogen activator inhibitor type 1 (PAI-1) expression or function may be involved in both fibrin deposition and accumulation of extracellular matrix, we have studied the effects of CR on the expression of PAI-1 in kidneys from female B/W mice fed either ad libitum or on a 40% CR diet. By immunohistochemistry and immunoblotting, we found that the glomerular levels of PAI-1 antigen were highest in older ad lib fed animals with more advanced glomerular disease. Increased levels of PAI-1 protein were paralleled by increased levels of PAI-1 mRNA in total RNA extracted from renal cortex and in diseased glomeruli as detected by in situ hybridization. CR diminished the accumulation of PAI-1 protein and reduced the expression of PAI-1 mRNA. Thus, glomeruli from animals fed ad lib showed much greater deposition of PAI-1 protein, increased expression of PAI-1 mRNA, and more severe histological abnormalities than animals on a CR diet. The differences between CR and ad lib animals were more pronounced in animals studied at 9 to 10 months versus those at 3 to 4 months of age. These observations indicate that the ameliorating effects of CR include diminished PAI-1 gene expression and decreased localization of PAI-1 in glomeruli.

Animals↗

PubMed1994

Genotype effects on the antioxidant enzymes activity and mRNA expression in liver and kidney tissues of autoimmune-prone MRL/MpJ-lpr/lpr mice.

Congeneic pairs of MRL/lpr and MRL/++ (+/+) mice differ in incidence of autoantibodies, lymphoproliferative disease and survival, characteristics that are linked to immunological abnormalities. MRL/lpr mice have a significantly shorter life span compared to +/+ mice. Because a weak antioxidant defense and an increased generation of free radicals are generally implicated in the severity of many autoimmune disease, the present study was undertaken to compare the influence of genotype on lipid composition, lipid peroxidation and expression of mRNA, and activity of antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in the livers and kidneys of these mice. The expression of SOD, GSH-Px and CAT mRNAs was significantly higher (P < 0.05) in the livers of +/+ mice, while in the kidneys only SOD expression was found significantly higher in +/+ mice when compared to MRL/lpr mice. Further, the activity of cytosolic SOD and GSH-Px was also found significantly higher (P < 0.001) in the livers of +/+ mice. Both livers and kidneys of MRL/lpr mice exhibited significantly higher levels of arachidonic acid (20:4(n-6)), significantly higher generation of thiobarbituric acid reactive substances (TBARS) and higher estimated peroxidation index than the +/+ mice. In addition, the MRL/lpr mice had higher levels of serum anti-cardiolipin antibodies. In summary, the results from the present study indicate that besides several immune-related abnormalities, the MRL/lpr mice may exhibit their inability to cope with oxidative stress due to a poor antioxidant defense system.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Decreased pro-inflammatory cytokines and increased antioxidant enzyme gene expression by omega-3 lipids in murine lupus nephritis.

Enrichment of diet with omega-3 lipid rich-menhaden fish oil (FO) when fed ad libitum to autoimmune lupus-prone NZB/NZW F1 (B/W) female mice delayed the onset and slowed progression of renal disease while significantly extending life-span compared to omega-6 lipid rich-corn oil (CO)-fed mice. Northern blot analysis of kidneys from FO-fed mice revealed no detectable levels of IL-1 beta, IL-6 and TNF alpha mRNA contrasted to levels that were easily detected in CO-fed mice. In contrast to the cytokines, FO-fed mice showed higher renal levels of the antioxidant enzymes-catalase, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD)-mRNAs compared to CO-fed mice. The results suggest that dietary supplementation with FO, as compared to CO, inhibits the production of pro-inflammatory cytokines and ameliorates immune-complex-mediated kidney injury possibly by enhancing the ability of cells to dispose of harmful reactive oxygen intermediates.

Animals↗

PubMed1994

Effects of n-3 and n-6 fatty acids on the activities and expression of hepatic antioxidant enzymes in autoimmune-prone NZBxNZW F1 mice.

Menhaden fish oil (FO) containing n-3 fatty acids dramatically extends the life span and delays the onset and progression of autoimmune disease in (NZBxNZW)F1 (B/W) female mice as compared to those fed corn oil (CO) rich in n-6 lipids. As an inefficient antioxidant defense system has been linked to autoimmune diseases, the present study was undertaken to determine whether the protective action of n-3 lipids is mediated through their antioxidant defense system. Weanling B/W mice were fed a nutritionally adequate, semipurified diet containing CO or krill oil (KO) or FO at 10% level (w/w) ad libitum until the mice were 6.5 months old. All diets contained the same level of vitamin E (21.5 mg/100 g diet). We compared the effects of feeding n-6 and n-3 lipids on survival, kidney disease, hepatic microsomal lipid composition, peroxidation, and on the activity and mRNA expression of the antioxidant enzymes catalase, glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in 6.5-month-old B/W mice. The results showed that when compared to livers from CO-fed mice, livers from KO- and FO-fed mice showed: (i) significantly higher (P < 0.001) activities and expression of CAT, GSH-Px and SOD; (ii) significantly lower (P < 0.001) arachidonic acid (20:4n-6) and linoleic acid (18:2n-6) and higher (P < 0.001) eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) levels in hepatic microsomes; and (iii) significantly lower (P < 0.001) estimated peroxidation indices and thiobarbituric acid reactive substances generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Activation of nuclear factor kappa B in human lymphoblastoid cells by low-dose ionizing radiation.

Nuclear factor kappa B (NF-kappa B) is a pleiotropic transcription factor which is involved in the transcriptional regulation of several specific genes. Recent reports demonstrated that ionizing radiation in the dose range of 2-50 Gy results in expression of NF-kappa B in human KG-1 myeloid leukemia cells and human B-lymphocyte precursor cells; the precise mechanism involved and the significance are not yet known. The present report demonstrates that even lower doses of ionizing radiation, 0.25-2.0 Gy, are capable of inducing expression of NF-kappa B in EBV-transformed 244B human lymphoblastoid cells. These results are in a dose range where the viability of the cells remains very high. After exposure to 137Cs gamma rays at a dose rate of 1.17 Gy/min, a maximum in expression of NF-kappa B was seen at 8 h after a 0.5-Gy exposure. Time-course studies revealed a biphasic time-dependent expression after 0.5-, 1- and 2-Gy exposures. However, for each time examined, the expression of NF-kappa B was maximum after the 0.5-Gy exposure. The expression of the p50 and p65 NF-kappa B subunits was also shown to be regulated differentially after exposures to 1.0 and 2.0 Gy.

Dose-Response Relationship, Radiation↗

PubMed1992

Overexpression of the epidermal growth factor receptor in human pancreatic cancer is associated with concomitant increases in the levels of epidermal growth factor and transforming growth factor alpha.

The epidermal growth factor (EGF) receptor is activated by both EGF and transforming growth factor-alpha (TGF-alpha). Using immunohistochemical and immunoblotting techniques we now report that the EGF receptor, EGF, and TGF-alpha are found in both pancreatic acini and ducts in the normal human pancreas, and that all three proteins are expressed at higher levels in human pancreatic cancer tissues. Using in situ hybridization techniques, we also report that the mRNA encoding the EGF receptor, EGF, and TGF-alpha colocalize with their respective proteins. Northern blot analysis of total RNA indicates that, by comparison with the normal pancreas, the pancreatic tumors exhibit a 3-, 15-, and 10-fold increase in the mRNA levels encoding the EGF receptor, EGF, and TGF-alpha, respectively. Furthermore, by in situ hybridization, there is a marked increase in these mRNA moieties within the tumor mass. These findings suggest that EGF and TGF-alpha may participate in the regulation of normal pancreatic exocrine function, and that overexpression of the EGF receptor and its two principal ligands may contribute to the pathophysiological processes that occur in human pancreatic cancer.

Adult↗

PubMed1991

Differential binding and biological activities of epidermal growth factor and transforming growth factor alpha in a human pancreatic cancer cell line.

The binding characteristics and biological activities of epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) were studied in T3M4 human pancreatic cancer cells. Scatchard analysis of 125I-EGF binding data at pH 7.4 indicated the presence of two orders of binding sites: a high-affinity site (Kd = 0.58 nM; 25,300 sites/cell) and a low-affinity site (Kd = 7.0 nM; 484,000 sites/cell). At pH 8.5, there was a decrease in the number of high-affinity sites. In contrast, only a single order of high-affinity sites was detected with 125I-TGF-alpha at either pH 7.4 (Kd = 0.57 nM; 100,200 sites/cell) or pH 8.5 (Kd = 0.70 nM; 230,400 sites/cell). The two ligands bound to the same receptor, as determined in cross-linking experiments and in competitive binding assays performed in the presence of an anti-EGF receptor antibody that allows for EGF binding. Phosphoamino acid analysis of the immunoprecipitated EGF receptor indicated that EGF exerted a greater effect than TGF-alpha on tyrosine phosphorylation of the receptor. EGF and TGF-alpha also exhibited different potencies with respect to their effects on inositol 1,4,5-trisphosphate generation and exerted divergent effects on the kinetics of inositol 1,4,5-trisphosphate formation. These findings point to dissimilar interactions of EGF and TGF-alpha with the EGF receptor in T3M4 cells, which may lead to differential activation of signal transduction pathways by these ligands.

Epidermal Growth Factor↗

PubMed1991

Basic fibroblast growth factor is a calcium-mobilizing secretagogue in rat pancreatic acini.

Basic fibroblast growth factor (bFGF) induced a marked increase in the levels of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and a rapid rise in cytosolic free calcium [Ca2+]i levels in rat pancreatic acini. The bFGF-mediated calcium transient was not dependent on the presence of extracellular calcium, and was abolished by pretreatment of acini with carbachol. bFGF stimulated amylase release in pancreatic acini in a monophasic, dose-dependent manner, and this effect was blocked by neutralizing anti-bFGF antibodies. At much higher concentrations, epidermal growth factor (EGF), but not insulin-like growth factor-I (IGF-I), partially mimicked some of the actions of bFGF. These findings suggest that bFGF is a previously unrecognized calcium-mobilizing pancreatic secretagogue that may participate in the regulation of pancreatic exocrine function.

Amylases↗

PubMed1991

Cholecystokinin-induced phosphatidylinositol hydrolysis in rat pancreatic acinar cells: modulation by extracellular calcium and manganese.

The role of extracellular calcium in modulating the actions of cholecystokinin octapeptide (CCK8) on phosphatidylinositol 4,5-bisphosphate hydrolysis was studied in freshly isolated rat pancreatic acini and cultured AR42J cells. In both cell types, CCK8 rapidly induced the formation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and 1,3,4, 5-tetrakisphosphate [Ins(1,3,4,5)P4]. The actions of CCK8 were inhibited by lanthanum and manganese, agents that block transmembrane calcium fluxes, and by chelation of extracellular calcium with EGTA. In pancreatic acini, lanthanum and manganese also partially inhibited the effects of carbachol and bombesin on Ins(1,4,5)P3 and Ins(1,3,4,5)P4 levels. In acini, the CCK8-mediated increases in Ins(1,4,5)P3 and Ins(1,3,4,5)P4 levels were progressively greater as the extracellular calcium concentration was raised from the micromolar range to 1.28 mM and progressively smaller as the manganese concentration was raised from 10 microM to 1 mM. Furthermore, the CCK8-mediated rise in Ins(1,4,5)P3 levels was partially attenuated by the calcium channel blockers verapamil, diltiazem, and nifedipine. These findings indicate that extracellular calcium enhances the ability of CCK8 and other calcium-mobilizing agonists to generate biologically active inositol phosphates in pancreatic acinar cells.

Animals↗

PubMed1991

Alteration of cholecystokinin-mediated phosphatidylinositol hydrolysis in pancreatic acini from insulin-deficient rats. Evidence for defective G protein activation.

Insulin deficiency leads to a decreased ability of cholecystokinin octapeptide (CCK-8) to raise cytosolic free-calcium levels in the pancreatic acinar cell. To elucidate the mechanisms underlying this defect, we studied the effects of CCK-8 on phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis in pancreatic acini prepared from nondiabetic and streptozocin-induced diabetic rats. Analysis by high-pressure liquid chromatography indicated that, in diabetic rat acini, the CCK-8-mediated increase in [3H]inositol 1,4,5-trisphosphate ([3H]IP3) levels was delayed, and the increase in [3H]inositol 1,3,4,5-tetrakisphosphate ([3H]IP4) levels was markedly attenuated compared with nondiabetic rat acini. The expected increase in the mass levels of IP3, measured in a competitive binding assay, was reduced in the diabetic group after incubation with CCK-8, carbachol, and bombesin. Phospholipase C activity was decreased by 30% in diabetic rat acini, whereas the specific activity of PIP2 and the amount of myo-[3H]inositol in the free and trichloroacetic acid-precipitable pools were similar in both groups. The nonhydrolyzable analogue of GTP guanosine-5'-O-(3'-thiotriphosphate) rapidly enhanced IP3 levels in permeabilized acini, and the percent increase above basal was greater in the diabetic group. When added for 5 s or 2 h, insulin did not alter basal or CCK-8-stimulated [3H]IP3 and [3H]IP4 levels in either nondiabetic or diabetic rat acini. However, after a 4-h incubation, insulin increased basal [3H]IP3 and [3H]IP4 levels in diabetic rat acini and potentiated the actions of CCK-8 on both inositol phosphates. Insulinlike growth factor I did not alter [3H]IP3 and [3H]IP4 levels either acutely or after a 4-h incubation. These findings point to a defect in the signal-transduction pathway that is activated by CCK-8 and other calcium-mobilizing agonists in the diabetic rat pancreas and suggest that insulin, acting via its own receptor, exerts long-term regulatory effects on PIP2 hydrolysis in the pancreatic acinar cell.

Animals↗

PubMed1990

Hypoglycemic activity of Swertia chirayita (Roxb ex Flem) Karst.

Hexane fraction of S. chirayita (250 mg/kg body wt.) induced significant fall in blood sugar and significant increase in plasma IRI simultaneously after single oral administration without influencing liver glycogen concentration in albino rats. On the other hand, daily administration for 28 days resulted in significant lowering of blood sugar and increase in plasma IRI along with a significant rise in liver glycogen. Intestinal absorption of glucose was not inhibited by hexane fraction. It is suggested that hexane fraction of S. chirayita possibly acts through its insulin releasing effect.

Animals↗

PubMed1989

Blood sugar lowering potentiality of selected Cucurbitaceae plants of Indian origin.

Using five experimental models, the blood sugar lowering efficacy of eight plants of Cucurbitaceae family has been assessed. The ethanolic extract of Cucumis sativus Linn, Cucumis melo utilissimum Roxb, Cucumis melo Linn, Benincasa hispida Thunb Cogn and Tricosanthes anguina Nees, when administered in 250 mg/kg dose, orally to rats failed to lower blood sugar or to depress the peak value, after glucose load. However, ethanolic extract of Momordica charantia Linn plant and Coccinia indica Whit and Arn root significantly lowered blood sugar in fasted model and depressed the peak value in glucose loaded model. Ethanolic extract of Tricosanthes dioica Roxb plant caused a significant lowering of blood sugar in fasted rats and depressed the peak value in glucose loaded single and longterm fed groups of rats. The ethanolic extract of the aerial part of T. dioica also induced significant depression in the peak values in the glucose loaded models.

Analysis of Variance↗

PubMed1989

Anti-secretagogue effect of lithium on isolated rat islets of Langerhans.

Administration of lithium carbonate solution (50 mg/kg, po, twice daily) to Charles Foster male albino rats for 45 consecutive days caused an intolerance to oral glucose. Inhibition in (pro)insulin biosynthesis followed by a significant fall in immunoreactive insulin release was seen in islets isolated from identically treated rats. As the activities of acid phosphatase and cathepsin B were unaltered, it is possible that the anti-secretagogue effect is sequential to inhibition of (pro)insulin biosynthesis by lithium.

Animals↗