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NGF and bFGF protect rat hippocampal and human cortical neurons against hypoglycemic damage by stabilizing calcium homeostasis.

NGF and bFGF have recently been shown to have biological activity in central neurons, but their normal functions and mechanisms of action are unknown. Since central neurons are particularly vulnerable to hypoglycemia that occurs with ischemia or insulin overdose, we tested the hypothesis that growth factors can protect neurons against hypoglycemic damage. NGF and bFGF each prevented glucose deprivation-induced neuronal damage in human cerebral cortical and rat hippocampal cell cultures (EGF was ineffective). Protection was afforded when the growth factors were administered before (NGF and bFGF) or up to 12 hr following (NGF) the onset of hypoglycemia. Direct measurements of intracellular calcium levels and manipulations of calcium influx demonstrated that sustained elevations in intracellular calcium levels mediated the hypoglycemic damage. NGF and bFGF each prevented the hypoglycemia-induced elevations of intracellular calcium. These findings indicate that growth factors can stabilize neuronal calcium homeostasis in central neurons and thereby protect them against environmental insults.

Calcium↗

Hypoglycemic effect of Rehmannia glutinosa oligosaccharide in hyperglycemic and alloxan-induced diabetic rats and its mechanism.

The hypoglycemic and anti-diabetic effect of Rehmannia glutinosa oligosaccharide (ROS) in glucose-induced hyperglycemic and alloxan-induced diabetic rats and its mechanism was investigated in this paper. It was found that pretreatment of ROS in normal rats with 100 mg/kg for 3 days, i.p., induced a partial prevention of hyperglycemia caused by glucose (2g/kg, i.p.), while when hyperglycemia was induced in adrenalectomized (ADX) rats, the preventive effect of ROS on hyperglycemia was lost. In alloxan-induced diabetic rats, ROS (100 mg/kg for 15 days, i.p.) showed a significant decrease in blood glucose level and hepatic glucose-6-phosphatase activity with an increase in hepatic glycogen content. Furthermore, ROS raised plasma insulin level and lowered plasma corticosterone level in alloxan-induced diabetic rats. The results indicated that oligosaccharide of Rehmannia glutinosa Libosch. exerted a significant hypoglycemic effect in normal and alloxan-induced diabetic rats. The regulatory mechanism of ROS on glucose metabolism was adrenal dependent and had a close relation with the neuroendocrine system.

Alloxan↗

Hypoglycemic potency of novel trivalent chromium in hyperglycemic insulin-deficient rats.

Two sources of chromium III, "chromium 454" and "chromium picolinate," were tested in insulin-deficient Streptozocin-treated diabetic rats. This model was selected in order to evaluate the possibility of any hypoglycemic potency of chromium in a relative absence of blood insulin concentration. Three weeks of the treatment with CRC454 and CrP resulted in a 38% and 11% reduction of blood glucose levels, respectively. Body weight gains were equally improved by both treatments. Blood levels of CK, ALT and AST were significantly reduced by CRC454 and CrP. These results might suggest that any hypoglycemic effect of trivalent chromium under insulin-deficient conditions could be largely dependent upon the type of chromium agent and associated characteristics such as solubility and bioavalibility. In contrast, improvement of body weight gains and blood levels of CK, AST and ALT seems to be less dependent on the type of chromium compound under these experimental conditions. In conclusion, CRC454 showed significant reduction of hyperglycemia under insulin-deficient conditions.

Alanine Transaminase↗

Depletion of ATP and release of presynaptic inhibition in the CA1 region of hippocampal slices during hypoglycemic hypoxia.

Transient recovery (TR) of evoked synaptic potentials and ATP depletion during the late stage of hypoxic hypoglycemic insults were investigated in rat hippocampal slices. TR was observed not only in the late stage of insult, but also during recovery. The concentration of ATP corresponded to the appearance (27% of control) and disappearance (15% of control) of TR. Paired pulse studies showed the presynaptic nature of the release of inhibition of synaptic transmission during TR. Both N- and P/Q-type voltage-dependent calcium channels were involved in the appearance of TR. This evidence suggests that underlying mechanisms of TR appearance during hypoxic hypoglycemic insult might be related to ATP depletion and release of A1 adenosine receptor mediated inhibition of presynaptic voltage-dependent calcium channels.

Adenosine Triphosphate↗

Hypoglycemic effects of the wood of Taxus yunnanensis on streptozotocin-induced diabetic rats and its active components.

Hypoglycemic effects of the H(2)O and MeOH extracts of the wood of Taxus yunnanensis were examined in streptozotocin (STZ)-induced diabetic rats. The H(2)O extract significantly lowered the fasting blood glucose level by 33.7% at a 100mg/kg dose on intraperitoneal administration. From the active H(2)O extract of the wood, three lignans, i.e., isotaxiresinol (1), secoisolariciresinol (2) and taxiresinol (3), were isolated as major components. These lignans were further tested for their hypoglycemic effects on the same experimental model. At a dose of 100mg/kg (i.p.), isotaxiresinol (1) reduced the fasting blood glucose level of diabetic rats by 34.5%, while secoisolariciresinol (2) and taxiresinol (3) reduced by 33.4% and 20.9%, respectively. The blood glucose lowering effects of 1 and 2 were stronger than the mixture of tolbutamide (200mg/kg) and buformin (1mg/kg) used as a positive control, which lowered fasting blood glucose level by 24.0%.

Animals↗

Up-regulation of macrophage migration inhibitory factor gene and protein expression in glial tumor cells during hypoxic and hypoglycemic stress indicates a critical role for angiogenesis in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the most malignant variant of human glial tumors. A prominent feature of this tumor is the occurrence of necrosis and vascular proliferation. The regulation of glial neovascularization is still poorly understood and the characterization of factors involved in this process is of major clinical interest. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine released by leukocytes and by a variety of cells outside of the immune system. Recent work has shown that MIF may function to regulate cellular differentiation and proliferation in normal and tumor-derived cell lines, and may also contribute to the neovascularization of tumors. Our immunohistological analysis of MIF distribution in GBM tissues revealed the strong MIF protein accumulation in close association with necrotic areas and in tumor cells surrounding blood vessels. In addition, MIF expression was frequently associated with the presence of the tumor-suppressor gene p53. To substantiate the concept that MIF might be involved in the regulation of angiogenesis in GBM, we analyzed the MIF gene and protein expression under hypoxic and hypoglycemic stress conditions in vitro. Northern blot analysis showed a clear increase of MIF mRNA after hypoxia and hypoglycemia. We could also demonstrate that the increase of MIF transcripts on hypoxic stress can be explained by a profound transcriptional activation of the MIF gene. In parallel to the increase of MIF transcripts, we observed a significant rise in extracellular MIF protein on angiogenic stimulation. The data of our preliminary study suggest that the up-regulation of MIF expression during hypoxic and hypoglycemic stress might play a critical role for the neovascularization of glial tumors.

Blotting, Western↗

Hyperaminoacidemia due to the accumulation of gluconeogenic amino acid precursors in hypoglycemic small-for-gestational age infants.

The postnatal (3 to 12 hours) plasma amino acid patterns of normal full-term, nonhypoglycemic, and hypoglycemic small-for-gestational age infants were compared. Seventeen amino acid were separated by automatic column chromatography. It was found that hypoglycemia in SGA newborn infants was associated with a marked increase in total serum amino acid concentrations. This hyperaminoacidemia, which was mainly due to the increase in concentrations of alanine, glycine, proline, and valine, apparently reflected a decreased heapatic gluconeogenic capacity. A significant inverse correlation was observed between concentration of blood glucose and the accumulation of gluconeogenic amino acids. The proportionate accumulation of alanine, glycine, proline, and valine suggests a closely interrelated production and release of these amino acids from the peripheral pools. It is concluded that the changes in concentrations of plasma amino acids occurring in hypoglycemic SGA infants can be helpful in understanding the relative contribution of individual amino acids to gluconeogenesis in the human infant.

Alanine↗

The mechanism of hypoglycemic action of the semi-purified fractions of Averrhoa bilimbi in streptozotocin-diabetic rats.

In the present study, we have examined the possible mechanism of the hypoglycemic action of the semi-purified fractions of an ethanolic extract of Averrhoa bilimbi Linn (Oxalidaceae) leaves (ABe) in streptozotocin-diabetic male Sprague-Dawley (SD) rats. The ABe was partitioned with water and butanol to yield a butanol-soluble fraction (BuF) and a water-soluble fraction (AF). The AF was further partitioned with ethyl acetate and hexane to obtain ethyl acetate (EF) and hexane (HF) soluble fractions. The hypoglycemic property of each fraction was assessed by the oral glucose tolerance test (OGTT) at a dose of 125-mg/kg-body weight in streptozotocin (STZ)-diabetic rats (STZ 60 mg/kg i.p.). Fractions AF, BuF and the reference drug metformin (500 mg/kg body weight), produced significant blood glucose-lowering effect in the diabetic rats when compared to the vehicle (distilled water). In the long-term study, the diabetic rats were randomly divided into 4 groups and treated orally by gavage with vehicle, AF (125 mg/kg body weight), BuF (125 mg/kg body weight), and metformin (500 mg/kg body weight) respectively twice a day for 14 days. On day 7 and day 14, AF and BuF, like the reference drug, metformin, lowered the fasting blood glucose concentration significantly (P < 0.05) when compared with the vehicle. The serum insulin level was significantly increased in the AF-treated rats only on day 14 when compared to that in the vehicle-treated rats on day zero (P < 0.05). The serum insulin level in BuF-treated rats was also significantly higher (P < 0.05) on both day 7 and day 14 compared to that on day zero. Hepatic glucose-6-phosphatase activity was significantly lower (P<0.05) in AF- and metformin-treated groups, but not in BuF-treated groups, compared to that in vehicle-treated group. However, there was no change in hepatic glycogen content in AF-, BuF- and metformin-treated group compared to the vehicle-treated group. These results indicate that AF is more potent than BuF in the amelioration of hyperglycemia in STZ-diabetic rats and is a potential source for the isolation of new orally active agent(s) for anti-diabetic therapy.

Animals↗

[Diffusion-weighted magnetic resonance imaging in hypoglycemic coma].

Hypoglycemia is a classic cause of coma and can result in irreversible neuronal loss. Until now, the main prognostic factors were depth of hypoglycemia and duration of coma. We report the case of a 55-Year-old woman who suffered severe hypoglycemic coma with abnormal cortico- subcortical diffusion weighted MR images. These MRI abnormalities preceded severe atrophy of these cerebral areas. This findings suggests that diffusion abnormalities in hypoglycemic coma may be related to neuronal loss and may thus have prognostic value.

Alcoholism↗

Hypoglycemic hemiplegia: a case study.

A 33-year-old man was seen in the emergency room with hypoglycemic hemiparesis of his left side. Hypoglycemic hemiparesis is an underrecognized manifestation of hypoglycemia and can mimic cerebrovascular disease, especially in the elderly. Although this is uncommon, hypoglycemia should be considered a part of the neurologic workup of any patient with a new onset of hemiparesis.

Adult↗

The effect of hypoglycemic sulfonylureas on human red blood cell transglutaminase activity.

We have examined the effect of glipizide, a hypoglycemic sulfonylurea, upon transglutaminase activity in human red blood cells. In a first series of experiments the in vitro effect of the drug was assessed. The results obtained showed that glipizide inhibits transglutaminase activity in human red blood cells. In a second approach, glipizide was administered orally to six type 2 diabetic patients during 3 months, in order to evaluate the long-term effect upon transglutaminase activity. Again, glipizide induced a significant decrease in the enzyme activity in blood red cells (P less than 0.01). We suggest that treatment of type 2 diabetes mellitus with hypoglycemic sulfonylureas could improve insulin effects by inhibiting cellular transglutaminase activity.

Calcium↗

Suicidal overdoses with hypoglycemic agents.

Suicide attempts using hypoglycemic agents are uncommon but are associated with a high level of morbidity and mortality. Their recognition is sometimes difficult and the duration of hypoglycemic effect is often prolonged. Two cases that illustrate the difficulties encountered in recognition and therapy are described. Effective therapy depends on adequate glucose supplementation to maintain euglycemia. Therapeutic intervention often must be maintained for several days. Glucocorticoids may be useful in difficult cases. Other modes of therapy, including glucagon, are unproven or controversial.

Adolescent↗

Hypoglycemic and hypoxic modulation of cortical micro-EEG activity in rat brain slices.

OBJECTIVE: Electroencephalogram (EEG) recordings exhibit stereotypic alterations during transient ischemia in mammals. One disadvantage of using in vitro models for ischemia studies is the lack of a sensitive electrophysiological measure for the degree of ischemic damage to a large population of neurons. The present study examined effects of hypoglycemia, hypoxia or both on an in vitro micro-EEG model, to determine whether this model provides a sensitive measure. METHODS: Theta frequency (4-8 Hz) micro-EEG oscillations were evoked in rat neocortical brain slices using the cholinergic agonist carbachol (100 microM) and the GABA(A) antagonist bicuculline (10 microM). Extracellular field micro-EEG signals and whole cell patch clamp recordings were used to monitor electrical activity. RESULTS: Upon removal of oxygen and/or glucose, theta oscillation amplitudes progressively declined to isoelectric levels. Low frequency delta oscillations (0.5-3.0 Hz) and burst suppression discharges were prominent during hypoglycemic episodes and upon recovery. Time to onset of isoelectric activity was faster in slices deprived of both glucose and oxygen (7.0 +/- 1.8 min) and oxygen alone (5.0 +/- 1.5 min) compared to hypoglycemia alone (25.6 +/- 3.8 min, P < 0.01, ANOVA). Hypoxia and hypoglycemia-induced isoelectric activity occurred prior to significant population spike depression from control levels (87.7 +/- 16.9% control amplitude, P > 0.35 (t test compared with control) for hypoglycemia; 93.6 +/- 27.0%, P > 0.72 for hypoxia). Spreading depression (SD) was observed in 11/12 (91.7%) slices deprived of both sugar and oxygen, but not in hypoxic (0/4) or hypoglycemic (0/5) slices. In all cases, SD occurred later than isoelectric activity. Theta oscillations recovered within 10 min in 12/13 (92.3%) slices that did not undergo SD, but slices that underwent SD failed to recover theta activity (0/4), though all (4/4) at least partially recovered the population spike (>40%). CONCLUSIONS: These results suggest that synchronized micro-EEG activity may be a useful and sensitive indicator of early-onset and possibly reversible ischemic damage.

Animals↗

Hypoglycemic and antihyperglycemic effect of Brassicajuncea diet and their effect on hepatic glycogen content and the key enzymes of carbohydrate metabolism.

Plants in the form of food or other remedial forms have been used for the treatment of various human ailments. Diabetes is one such disorder in which various form of plants and herbal remedies have been tried. Brassicajuncea (BJ) seeds (Rai) are consumed in India as a spice in various food items. Previous studies have shown the hypoglycemic effect of this plant in rats. The present study was undertaken to study the hypoglycemic and antihyperglycemic of various strengths (5, 10 and 15%) of BJ seed diet in alloxan and streptozotocin induced diabetes in albino rats. In addition, key enzymes of carbohydrate metabolism (glucokinase--EC 2.7.1.1, hexokinase--EC 2.7.1.1, and phosphofructokinase--EC 2.7.1.11) and hepatic glycogen content was also assessed to understand the mechanism of action. BJ diet (10 and 15%) showed significant antihyperglycemic effect in alloxan (35 mg/kg) but not in STZ (60 mg/kg) rats. It also failed to modulate the hepatic glycogen content and enzyme activities.

Alloxan↗

Correlates of hypoglycemic fear in type I and type II diabetes mellitus.

We examined whether fear of hypoglycemia in insulin-dependent diabetes mellitus was associated with (a) higher levels of trait anxiety and general fearfulness, (b) difficulty in differentiating symptoms of anxiety and hypoglycemia, and (c) past experience with hypoglycemia. Joslin Diabetes Center outpatients with Type I and Type II diabetes (N = 232), all requiring insulin, were surveyed. Type I patients experienced significantly more fear of hypoglycemia than Type II patients. For the Type I and Type II groups, higher scores on the Worry subscale of the Hypoglycemia Fear Survey (HFS-W) were associated with higher levels of trait anxiety and fear. Higher scores on the Behavior subscale (HFS-B) were associated with higher levels of fear. Among Type I subjects only, HFS-W scores were also positively associated with past hypoglycemic experience and with difficulty in differentiating anxiety and hypoglycemic symptoms. These latter relations remained significant even after the variance resulting from trait anxiety and fear was removed. Other significant associations with HFS-B scores were not observed.

Adaptation, Psychological↗

Hypoglycemic effect of trans-dehydrocrotonin, a nor-clerodane diterpene from Croton cajucara.

trans-Dehydrocrotonin (t-DCTN), a 19-nor-clerodane diterpene isolated from the bark of Croton cajucara Benth. (Euphorbiaceae) demonstrated a significant hypoglycemic activity in alloxan-induced diabetic rats but not in normal rats, at oral doses of 25 and 50 mg/kg body weight. The drug also effectively lowered the blood sugar levels in glucose fed normal rats. The hypoglycemic effect of t-DCTN was almost comparable to that produced by glibenclamide (2 mg/kg), a clinically useful drug. The results indicate the antihyperglycemic potential of t-DCTN.

Animals↗

The comparative effects of tolbutamide and the non-hypoglycemic analog carboxytolbutamide on guanylate cyclase activity.

Tolbutamide and its non-hypoglycemic analog carboxytolbutamide increased soluble and particulate guanylate cyclase [E.C.4.6.1.2] activity twofold in liver, lung, colon, pancreas, kidney cortex, heart and spleen at a concentration of 1 microM. The ED50 for stimulation of guanylate cyclase activity was 50 nM for both agents. No stimulation of guanylate cyclase activity was observed with either agent when their concentrations were decreased to 1 nM. Maximal enhancement was at a concentration of 100 nM for both agents. Butylated hydroxytoluene, an antioxidant and hydroxyl radical scavenger, completely blocked any enhancement of guanylate cyclase by carboxytolbutamide, suggesting that its effect was due to a nonspecific oxidation reaction. Tolbutamide's augmentation of guanylate cyclase activity was not blocked by butylated hydroxytoluene. Varying the concentration of the guanylate cyclase co-factor manganese indicated that these sulfonylureas could not maximally activate guanylate cyclase without manganese being present. In addition to increased insulin receptors in monocytes and fibroblasts, the present findings, plus similar findings with the oral hypoglycemic agent glibenclamide, may help explain the mechanism of the extra-pancreatic effects of oral sulfonylurea agents at the cellular level.

Animals↗

Plasma glucose concentrations at the onset of hypoglycemic symptoms in patients with poorly controlled diabetes and in nondiabetics.

We tested the hypothesis that during decrements in plasma glucose concentration, symptoms of hypoglycemia may occur at higher glucose concentrations in patients with poorly controlled insulin-dependent diabetes mellitus than in persons without diabetes. Symptoms of hypoglycemia and counterregulatory neuroendocrine responses were quantified during hypoglycemic and euglycemic clamp studies in eight patients with insulin-dependent diabetes mellitus selected because their hemoglobin A1 levels were above 10 percent. These data were compared with similar observations in 10 nondiabetic subjects studied previously. Glycemic thresholds--the plasma glucose concentrations during each hypoglycemic clamp study at which a given symptom or biochemical measurement first exceeded its 95 percent confidence interval determined in the euglycemic clamp studies--were calculated for each variable. The mean (+/- SE) glycemic threshold for the symptoms of hypoglycemia was 4.3 +/- 0.3 mmol per liter (78 +/- 5 mg per deciliter) in patients with poorly controlled diabetes--significantly higher (P less than 0.001) than the value of 2.9 +/- 0.1 mmol per liter (53 +/- 2 mg per deciliter) in subjects without diabetes. The mean glycemic thresholds for growth hormone, epinephrine, and cortisol secretions were not significantly different in the two groups. Thus, during decreases in the plasma glucose concentration, patients with poorly controlled insulin-dependent diabetes mellitus may experience symptoms of hypoglycemia at higher plasma glucose concentrations than persons without diabetes. The mechanism underlying this observation remains to be defined.

Adult↗