Mitochondria Of Diabetic Rats Research Articles

Bambusa vulgaris leaves reverse mitochondria dysfunction in diabetic rats through modulation of mitochondria biogenic genes.

There is evidence that mitochondrial dysfunction mediated by hyperglycemia increases the incidence of diabetes and age-related insulin resistance. Thus, maintaining mitochondrial integrity may provide alternative therapeutic approach in diabetes treatment. This study aimed to evaluate the effect of Bambusa vulgaris leaf extract on mitochondrial biogenesis in the pancreas of diabetic rats. 11weeks old male rats (n=30) were purchased, and sorted into the following groups: control, diabetic control, diabetes+metformin (100mg/kg), diabetes+Aq. B.vulgaris (100mg/kg), diabetes+Aq. B.vulgaris (200mg/kg), and diabetes+Aq. B.vulgaris (300mg/kg). Diabetes was induced in the rats by a single dose of 65mg/kg streptozotocin (STZ). The mRNA expression of genes related to mitochondria biogenesis (pgc-1α, Nrf2, GSK3β, AMPK and SIRT2) and genes of Nrf2-Keap1-ARE signaling pathway were determined by reverse transcriptase polymerase chain reaction. Molecular docking studies including lock and key docking and prime MM-GBSA were incorporated to identify the lead chemical compounds in Bambusa vulgari. The results showed that B.vulgaris leaf extract promotes mitochondrial biogenesis via altering the mRNA expression of mitochondrial master regulator pgc-1α, otherupstream genes, and the Nrf2-Keap1-ARE antioxidant pathway. Through molecular docking results, cryptochlorogenic acid, hesperidin, orientin, vitexin, scopolin, and neochlorogenic were found as the crucial chemicals in B.vulgaris with the most modulating effect on PGC-1α, AMPK, and GSK3. This study thus suggests that B.vulgaris leaf extract restores the integrity of mitochondria in diabetic rats.

THE IMPACT OF SUCCINATE DERIVATIVE PHENSUCCINAL ON MITOCHONDRIAL FUNCTION AND REDOX STATUS IN THE HEART OF RATS WITH TYPE 2 DIABETES

Dysfunction of cardiac mitochondria appears to play a substantial role in cardiomyopathy and is a promising therapeutic target for many cardiovascular diseases. Persistent hyperglycaemia and hyperlipidemia are believed to be the main causes of increased oxidative stress, mitochondrial dysfunctions, fibrosis and apoptosis of cardiomyocytes in diabetes. We have previously shown that the low-toxic succinate derivative – Phensuccinal (beta-phenylethylamide-2 hydroxy-succinanylic acid, Phe) possesses antioxidant and anti-inflammatory properties. The aim of this study was to assess the effects of Phe on the mitochondrial function and oxidative status in the heart of rats with T2DM. Materials and Methods. T2DM was induced in Wistar rats by a high-caloric diet during 14 weeks combined with intraperitoneal injections of 25 mg/kg streptozotocin twice per week. All diabetic animals were divided into two groups: treated with vehicle or with Phe (in dose 50 mg/kg/day) for four weeks after diabetes induction. Redox status of rats’ heart mitochondria was estimated by determination of reactive oxygen species (ROS) production, GSH level and activity of antioxidant enzymes (Mn-superoxide dismutase, glutathione peroxidase and glutathione reductase). Mitochondrial function was determined by activity of aconitase, succinate dehydrogenase and cytochrome C oxidase in rats’ cardiomyocytes. Results. It was established that Phe inhibited oxidative stress in isolated heart mitochondria of rats with T2DM, which was confirmed by decreasing ROS production and increasing GSH level compared to diabetic rats. The use of Phe led to a normalization of antioxidant enzymes (Mn-superoxide dismutase and glutathione peroxidase) activity in the heart of diabetic rats. In addition, Phe improved metabolic activity of the heart mitochondria activating aconitase and succinate dehydrogenase in cardiomyocytes. We can suggest that Phe ameliorate mitochondrial dysfunction decreasing oxidative stress and preventing deficiency in complex II of ETC in the heart of rats with type 2 diabetes. Conclusion. The data of the present study confirmed the positive effect of Phe on redox homeostasis and functional state of the heart mitochondria in diabetic rats. We suggest that the use of Phe may contribute to the amelioration of cardiovascular risk in type 2 diabetes

Geranylgeraniol Increases Autophagy And Mitophagy Gene Expression In Soleus Of Rats With Diabetes

The autophagy and mitophagy (selective autophagy for mitochondria) processes are important in maintaining muscle homeostasis, e.g., removing damaged mitochondria. With diabetes, skeletal muscle autophagy decreases. Geranylgeraniol (GG) has been shown to reduce mitochondrial damage; however, the effect of GG on basal autophagy and mitophagy in diabetic rats is not known. PURPOSE: To determine the effect of GG on selective autophagy and mitophagy genes in rats with diabetes induced by a high-fat diet (HFD) with streptozotocin (STZ). METHODS: Sprague-Dawley rats were divided into three groups: normal diet (CON; n = 11), HFD with 35 mg/kg body weight of STZ (HFD; n = 9), and HFD/STZ with 800 mg/kg body weight of GG (GG; n = 9). On the 7th week, soleus muscles were collected and analyzed for gene expression of LC3A, LC3B, P62, PINK1, PARKIN, DRP, and MFN. Gene data were normalized to CON. RESULTS: A significant (p < 0.05) condition effect was found for autophagy (LC3A, LC3B, and P62) and mitophagy (PINK, DRP, and MFN) gene expression. For autophagy, HFD (0.14 ± 0.03-fold) had significantly lower LC3A than CON (1.00 ± 0.22-fold), lower LC3B (0.67 ± 0.26-fold vs. 2.37 ± 0.72-fold) and P62 (0.44 ± 0.13-fold vs. 1.70 ± 0.35-fold) than GG. HFD trended to have lower LC3A than GG (0.14 ± 0.03-fold vs. 0.86 ± 0.26-fold; p = 0.066) while CON trended to have lower LC3B than GG (1.00 ± 0.07-fold vs. 2.37 ± 0.72-fold; p = 0.078). For mitophagy, HFD (0.32 ± 0.07-fold) and GG (0.51 ± 0.15-fold) had significantly lower PINK1 than CON (1.00 ± 0.13-fold). Further, HFD had lower MFN than GG (0.31 ± 0.08-fold vs. 1.46 ± 0.25-fold) and lower DRP than CON (0.48 ± 0.11-fold vs. 1.00 ± 0.15-fold). HFD trended to have lower PARKIN than GG (0.46 ± 0.08-fold vs. 1.38 ± 0.38-fold; p = 0.053) with no difference between GG and CON. CONCLUSION: In comparison to HFD, GG consumption improved the basal transcript abundance of the selective skeletal muscle autophagic and mitophagic genes, which could indicate an increased capacity to remove damaged mitochondria in diabetic rats.

Oxidative stress and hepatocellular mitochondrial dysfunction attenuated by asiatic acid in streptozotocin-induced diabetic rats

Oxidative stress produced by mitochondria is one of the main causes for diabetes associated complications. This study was planned to assess the efficacy of asiatic acid (AA) on oxidative stress mediated hepatocellular mitochondrial dysfunction in streptozotocin (STZ)-induced type-2 diabetic rats. Diabetic rats were generated by intraperitoneal injection of STZ administered as single dose at 40 mg/kg body weight (b. wt.). Then the rats were treated with 20 mg of AA or 600 μg of glibenclamide (Glib)/kg b. wt, once in a day for 45 days. The results of this study illustrated that diabetic rat liver mitochondrial malondialdehyde (MDA), reactive oxygen species (ROS) and protein carbonyl (PCO) levels were significantly increased at the same time antioxidant enzymes and non-enzymes status was markedly diminished when compared with the liver mitochondria of normal control rats. A marked reduction in ROS, MDA, PCO and significant amelioration in non-enzymatic and enzymatic antioxidants were observed in diabetic rats treated with AA or Glib as compared with untreated diabetic control rats. Tricarboxylic acid (TCA) cycle enzymes like isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase and electron transport chain (ETC) complexes activities were significantly diminished in diabetic rats. Besides, mitochondrial uncoupling protein-2 (UCP2) expression was significantly upregulated at the same time adenosine triphosphate (ATP) level and mitochondrial membrane potential (MMP) was markedly lowered in the mitochondria of diabetic rats. AA or Glib treatment with diabetic rats restored the TCA cycle enzymes activities, ETC complexes, UCP2, MMP and ATP level to near normal control rats as compared with untreated diabetic control rats. Hence, the results of the current study indicated that AA ameliorated mitochondrial function by attenuating oxidative stress in STZ-induced type-2 diabetic rats.

Ultrastructural and Functional Changes in Liver Mitochondria in a Rat Model of Type I Diabetes Mellitus

Abstract—The characteristics of the ultrastructure and functioning of mitochondria in the liver of Sprague Dawley rats in the experimental model of type I diabetes mellitus have been investigated. It has been found that diabetes mellitus induced in response to streptozotocin administration at a dose of 75 mg/kg body weight was accompanied by disturbances in the structural organization of mitochondrial cristae and a decrease in the size of the organelles compared to the control. It has been also demonstrated that in type I diabetes the respiratory rates of liver mitochondria in metabolic states 2, 3, and 4 increase. This may be associated with an increase in the total content of fatty acids in liver mitochondria of diabetic rats. At the same time, streptozotocin-induced diabetes mellitus in rats did not affect the indices of oxidative phosphorylation efficiency (ADP/O, respiratory control ratio, and phosphorylation time) in liver mitochondria.

Effects of pomegranate seed oil on oxidant/antioxidant balance in heart and kidney homogenates and mitochondria of diabetic rats and high glucose-treated H9c2 cell line.

Oxidative stress is a major cause of diabetes complications. The present study aimed to investigate the beneficial effects of Pomegranate Seed Oil (PSO) on diabetes-induced changes in oxidant/antioxidant balance of the kidney, heart and mitochondria from rats and H9c2 cell line. In these in vivo and in vitro studies, male rats were divided into four groups (twelve each): group 1 served as control, group 2-4 received a single dose of streptozotocin (60 mg/kg, i.p), groups 3 and 4 received PSO (0.36 and 0.72 mg/kg/daily, gavage), respectively. After three weeks, six rats of each group and one week later the remaining animals were anaesthetized and the hearts and kidneys were removed and homogenized. Mitochondrial fractions were separated and enzyme activities were measured in each sample. H9c2 cells were pretreated with high levels of glucose (35 mM), and then, incubated with PSO. Finally, cell viability test, reactive oxygen species production and lipid peroxidation were evaluated. Significant reduction in enzymes activity (Superoxide dismutase, Glutathione S-transferase and Paraoxonase 1), compensatory elevation in Glutathione Reductase, Glutathione Peroxidase and Catalase activity followed by reduction after one week and significant elevation in Oxidative Stress Index (OSI) were observed in diabetic group. PSO treatment resulted in a significant increase in enzymes activity and decreased OSI values compared to diabetic group in both tissue and mitochondrial fractions. PSO remarkably decreased glucose-induced toxicity, ROS level and lipid peroxidation in H9c2 cells. Results suggested that PSO has a protective effect against diabetes-induced alterations in oxidant/antioxidant balance in tissues, mitochondrial and H9c2 cell line.

Delayed treatment with NSC23766 in streptozotocin-induced diabetic rats ameliorates post-ischemic neuronal apoptosis through suppression of mitochondrial p53 translocation

NSC23766, a specific inhibitor of Rac1, has recently been shown to protect against cerebral ischemic injury, although the effects of NSC23766 in a diabetic model have not been examined. Therefore, the aim of our study was to investigate if NSC23766 provided neuroprotection in streptozotocin-induced diabetic rats and to determine the potential mechanism through which NSC23766 works. Diabetic Sprague–Dawley rats were subjected to right middle cerebral artery occlusion (MCAO) for 90 min. NSC23766 (10 or 30 mg kg−1) or isotonic saline were administered intraperitoneally twice daily starting 24 h after cerebral ischemia, for three consecutive days. Cerebral infarct volume, neurological deficit scores, neuronal apoptosis, and the release of cytochrome c, as well as the generation of ROS and mitochondrial integrity, were evaluated 96 h after reperfusion. In addition, the mitochondrial translocation of p53 and the expression of p53-upregulated modulator of apoptosis (PUMA) in the mitochondria of the cerebral ischemic cortex were determined by western blotting. NSC23766 not only ameliorated post-ischemic neuronal apoptosis but also decreased cerebral ischemia-induced mitochondrial p53 translocation and the expression of PUMA in mitochondria in diabetic rats. Thus, our data indicate that NSC23766 has therapeutic potential against cerebral ischemic reperfusion injury and that NSC23766 significantly ameliorates neuronal apoptosis by suppressing mitochondrial p53 translocation in streptozotocin-induced diabetic rats.

Membrane fluidity and lipoperoxidation of placental mitochondria in diabetic rats (953.2)

Oxidative damage on biological molecules has been proposed as a major cause of alterations observed during diabetes. In this study, using the excimer forming monitor dipyrenylpropane (DPyP), we measured membrane fluidity of placental mitochondria in diabetic rats with 19 days of gestation and its respective normoglycemic controls. A significant increment (p &lt; 0.001) of mitochondrial membrane fluidity was found in diabetic rats, along with MDA increment. Physicochemical parameters had changes, i.e. lower activation energies in gel (23.0 ± 5.0 vs. 18.2 ± 4.0 kJ/mol) and liquid‐crystalline (13.9 ± 1.3 vs. 12.0 ± 0.4 kJ/mol) phases in the diabetic group (p &lt; 0.05); the transition temperature was lower in diabetic (37.8 ± 1.6 vs. 30 ± 2.0 °C), p &lt; 0.05. There were several changes in fatty acid composition. These results provide further evidence that oxidative stress may play a role in the increment of mitochondrial membrane fluidity during pregnancy in diabetic rats despite the physical effects of lipoperoxides in membranes.Acknowledgements: CONACYT postdoctoral Fellowship to MCFG; financial support from DGAPA‐PAPIIT UNAM to RMZ; financial support from CIC‐UMSNH (2.16 to ASM) and CONACYT (169093 to ASM).

The Protective Effect of Fasudil on the Structure and Function of Cardiac Mitochondria from Rats with Type 2 Diabetes Induced by Streptozotocin with a High-Fat Diet Is Mediated by the Attenuation of Oxidative Stress

Dysfunction of cardiac mitochondria appears to play a substantial role in cardiomyopathy or myocardial dysfunction and is a promising therapeutic target for many cardiovascular diseases. We investigated the effect of the Rho/Rho-associated protein kinase (ROCK) inhibitor fasudil on cardiac mitochondria from rats in which diabetes was induced by a combination of streptozotocin (STZ) and a sustained high-fat diet. Eight weeks after diabetes was induced by a single intraperitoneal injection of 50 mg/kg STZ followed by a sustained high-fat diet, either fasudil (5 mg/kg bid) or equivalent volumes of saline (control) were administered over four weeks. Fasudil significantly protected against the histopathologic changes of cardiac mitochondria in diabetic rats. Fasudil significantly reduced the abundances of the Rho A, ROCK 1, and ROCK 2 proteins, restored the activities of succinate dehydrogenase (SDH) and monoamine oxidase (MAO) in cardiac mitochondria, inhibited the opening of the mitochondrial permeability transition pore, and decreased the total antioxidant capacity, as well as levels of malonyldialdehyde, hydroxy radical, reduced glutathione, and superoxide dismutase in heart. Fasudil improved the structures of cardiac mitochondria and increased both SDH and MAO activities in cardiac mitochondria. These beneficial effects may be associated with the attenuation of oxidative stress caused by fasudil treatment.

The effects of aerobic exercise training on oxidative stress and uitrastructure of pancreas tissue in diabetic rats

Objective To investigate the effects of aerobic exercise training on oxidative stress and ultrastructure of pancreas tissue in diabetic rats and the mechanism of protective effects of aerobic exercise training on pancreatic mitochondria in diabetic rats. Methods Thirty Sprague-Dawley rats were randomly divided into three groups:a normal control group,a diabetic model group and an exercise diabetic group,with 10 rats in each group.Type 2 diabetic rat models were established by intra-abdominal injection of streptozotocin (STZ).The success rate of establishing diabetic rat models was 85.7％.The normal control group and diabetic model group were not given exercise training.Exercise group was trained with 8 weeks of swimming of medium strength,eg.60 min/time,5 d/week. After training for 8 weeks, the activities of superoxide dismutase (SOD), glutathion peroxidase (GPX),nitric oxide synthase (NOS) and the contents of malondialdehyde (MDA) and nitric oxide (NO) in pancreatic mitochondria were observed respectively.The ultrastructures of pancreas tissue in rats were observed under electron microscope. Results After swimming training for 8 weeks,the activities of SOD and GPx in pancreatic mitochondria in exercise diabetic group elevated more obviously than those in diabetic model group ( P ＜ 0.05 ),while the activity of NOS and the contents of MDA and NO reduced obviously (P ＜ 0.05 ).Compared with diabetic model group,the ultrastructures of pancreas tissue in exercise diabetic group improved,and the histomorphology was similar to normal control group. Conclusions Aerobic exercise training can provide protective effects on pancreas in diabetic rats,and can enhance antioxidation ability to eliminate free radicals,improve the ultrastructures of pancreas tissue. Key words: Aerobic exercise; Diabetes mellitus; Pancreas; Oxidative stress; Ultrastructure

Proteome, Phosphoproteome, and Hydroxyproteome of Liver Mitochondria in Diabetic Rats at Early Pathogenic Stages

It has been proposed that mitochondrial dysfunction is involved in the pathogenesis of type 2 diabetes (T2D). To dissect the underlying mechanisms, we performed a multiplexed proteomics study on liver mitochondria isolated from a spontaneous diabetic rat model before/after they were rendered diabetic. Altogether, we identified 1091 mitochondrial proteins, 228 phosphoproteins, and 355 hydroxyproteins. Mitochondrial proteins were found to undergo expression changes in a highly correlated fashion during T2D development. For example, proteins involved in beta-oxidation, the tricarboxylic acid cycle, oxidative phosphorylation, and other bioenergetic processes were coordinately up-regulated, indicating that liver cells confronted T2D by increasing energy expenditure and activating pathways that rid themselves of the constitutively increased flux of glucose and lipid. Notably, activation of oxidative phosphorylation was immediately related to the overproduction of reactive oxygen species, which caused oxidative stress within the cells. Increased oxidative stress was also evidenced by our post-translational modification profiles such that mitochondrial proteins were more heavily hydroxylated during T2D development. Moreover, we observed a distinct depression of antiapoptosis and antioxidative stress proteins that might reflect a higher apoptotic index under the diabetic stage. We suggest that such changes in systematic metabolism were causally linked to the development of T2D. Comparing proteomics data against microarray data, we demonstrated that many T2D-related alterations were unidentifiable by either proteomics or genomics approaches alone, underscoring the importance of integrating different approaches. Our compendium could help to unveil pathogenic events in mitochondria leading to T2D and be useful for the discovery of diagnosis biomarker and therapeutic targets of T2D.

Diabetes impairs the enzymatic disposal of 4-hydroxynonenal in rat liver

This study assesses whether the HNE accumulation we formerly observed in liver microsomes and mitochondria of BB/Wor diabetic rats depends on an increased rate of lipoperoxidation or on impairment of enzymatic removal. There are three main HNE metabolizing enzymes: glutathione-S-transferase (GST), aldehyde dehydrogenase (ALDH), and alcohol dehydrogenase (ADH). In this study we show that GST and ALDH activities are reduced in liver microsomes and mitochondria of diabetic rats; in contrast, ADH activity remains unchanged. The role of each enzyme in HNE removal was evaluated by using enzymatic inhibitors. The roles of both GST and ALDH were markedly reduced in diabetic rats, while ADH-mediated consumption was significantly increased. However, the higher level of lipohydroperoxides in diabetic liver indicated more marked lipoperoxidation. We therefore think that HNE accumulation in diabetic liver may depend on both mechanisms: increased lipoperoxidation and decreased enzymatic removal. We suggest that glycoxidation and/or hyperglycemic pseudohypoxia may be involved in the enzymatic impairment observed. Moreover, since HNE exerts toxic effects on enzymes, HNE accumulation, deficiency of HNE removal, and production of reactive oxygen species can generate vicious circles able to amplify the damage.

Physical training reverses defect in mitochondrial energy production in heart of chronically diabetic rats.

This study examined the impact of physical training on cardiac mitochondrial respiration of rats with chronic diabetes mellitus. Diabetes was induced by an intravenous injection of STZ (50 mg/kg) and only rats with a blood glucose level between 14 and 22 mM 1 wk later were kept in the protocol. Exercise training was conducted on a treadmill with a progressive 10-wk program. Animals were killed at the end of the training program, and mitochondria were isolated from ventricular tissue by differential centrifugation. Both state 3 respiration and oxidative phosphorylation rates were depressed significantly in the mitochondria of diabetic rats. These alterations were reversed completely to normal by physical training, without any significant changes in plasma glucose or insulin levels. The activity of ANT was not affected by diabetes or training. These results indicate that the depressed OPR present in isolated heart mitochondria from chronically diabetic rats is reversed to normal by physical training, apparently by mechanisms independent of blood glucose control. This correction in mitochondrial energy production may explain the improvement in cardiac function previously reported in trained diabetic rats.

Improving effects obtained by the ovariectomy or treatment with tamoxifen of female diabetic rats over the function and enzyme activities of liver mitochondria.

In the present work we studied, in female chronic diabetic rats the effect of either the parenteral administration of tamoxifen (TAM) (500 micrograms.kg-1.day-1) for 15 days or the ovariectomy upon the respiration and oscillatory behaviour of intact mitochondria and the activities of 3-hydroxybutyrate dehydrogenase (HBD) and cytochrome c oxidase (Cox) of disrupted liver mitochondria. The treatment with TAM as well as the ovariectomy of diabetic animals significantly increased the respiratory control (RC) and the state 3 (S3) of respiration of intact liver mitochondria with the three substrates assayed (3-hydroxybutyrate, malate-glutamate and succinate). Both treatments also lowered significantly the damped factors of the oscillatory variation of liver intact mitochondria of diabetic rats. Moreover, the two above-mentioned treatments restored the activities of HBD and Cox of liver disrupted mitochondria to normal values. The effect of estrogens at level of its receptors in the modulation of liver mitochondrial function and liver HBD and Cox activities in chronic diabetes is discussed.

Incorporation of [32P]phosphate into the pyruvate dehydrogenase complex in rat heart mitochondria.

1. Evidence is given for three sites of phosphorylation in the alpha-chains of the decarboxylase component of purified rat heart pyruvate dehydrogenase complex, analogous to those established for procine and bovine complexes. Inactivation of rat heart complex was correlated with phosphorylation of site 1. Relative initial rates of phosphorylation were site 1 greater than site 2 greater than site 3. 2. Methods are described for measurement of incorporation of 32Pi into the complex in rat heart mitochondria oxidizing 2-oxoglutarate + L-malate (total, sites 1, 2 and 3). Inactivation of the complex was related linearly to phosphorylation of site 1 in mitochondria of normal or diabetic rats. The relative initial rates of phosphorylation were site 1 greater than site 2 greater than site 3. Rates of site-2 and site-3 phosphorylation may have been closer to that of site 1 in mitochondria of diabetic rats than in mitochondria of normal rats. 3. The concentration of inactive (phosphorylated) complex was varied in mitochondria from normal rats by inhibiting the kinase reaction with pyruvate at concentrations ranging from 0.15 to 0.4 mM. The results showed that the concentration of inactive complex is related linearly to incorporation of 32Pi into site 1. Inhibition of 32Pi incorporations with pyruvate at all concentrations over this range was site 3 greater than site 2 greater than site 1. 4. With mitochondria from diabetic rats, pyruvate (0.15-0.4 mM) inhibited incorporation of 32Pi into site 3, but it had no effect on the concentration of inactive complex or on incorporations of 32Pi into site 1 or site 2. It is concluded that site-3 phosphorylation is not required for inactivation of the complex in rat heart mitochondria. 5. Evidence is given that phosphorylation of sites 2 and 3 may inhibit reactivation of the complex by dephosphorylation in rat heart mitochondria.

Ultrastructural changes in Leydig cells of streptozotocininduced diabetic rats

Hyperglycemia (experimental diabetes) was induced in adult male rats by destruction of the pancreatic beta cells with a single intravenous injection of streptozotocin (STZ). Testes from diabetic, from insulin-treated diabetic, and from sham-injected normal rats were fxed by vascular perfusion. The fine structure of Leydig cells was examined at two, three, and four weeks after the STZ injection in the untreated diabetic animals, and at four weeks in the controls and insulin-treated diabetic rats. A number of morphological changes was observed in Leydig cells of untreated diabetic animals. Most obvious of these was an accumulation of lipid droplets, not normally present in Leydig cells in adults of this species. Smooth endoplasmic reticulum (SER) was markedly reduced in Leydig cells of the hyperglycemic rats. Several types of intracellular bodies were seen exclusively in Leydig cells of the untreated diabetic animals. Many resembled secondary lysosomes or dense bodies, while others appeared to be autophagic vacuoles. In addition, a small, granule-containing lamellar structure was seen either within a typical dense body or free in the cytoplasm. Myelin-like structures were commonly observed within the cytoplasm of the Leydig cell or within mitochondria. The appearance of the mitochondria in diabetic rats was otherwise normal. The extracellular spaces surrounding Leydig cells from untreated hyperglycemic rats also contained large accumulations of myelin-like material. These structural changes appear to be direct consequences of the diabetic state of the animals, since the ultrastructure of insulin-treated diabetic rats did not differ from that of the controls. These findings may reflect an alteration or breakdown of Leydig cell components normally involved in the synthesis of androgen, and correlate with previous reports of lowered circulating levels of testosterone in diabetic rats.

Depression of respiratory activities in the liver mitochondria of diabetic rats and the restorative action of insulin.

Depression of respiratory activities in the liver mitochondria of diabetic rats and the restorative action of insulin.