geranylgeranylacetone and Insulin-Resistance

Heat shock proteins (HSPs) are an important family of protective proteins. They are involved actively in an array of cellular processes, including protective effects on the cardiovascular system in response to various stimuli. Increasing evidence shows that pharmacologic interventions that induce expression of HSPs may be a novel approach for the treatment of cardiovascular diseases. However, agents that induce expression of HSPs used previously are toxic or have harmful side effects, which limit their clinical application. Geranylgeranylacetone (GGA) is not only a widely used antiulcer agent in Asia, but also a nontoxic inducer of HSPs expression. It increases the expression of HSPs rapidly in the presence of ischemia, anoxia, oxidative stress, and toxicants, thereby having significant protective effects. The cardioprotective effects of GGA have been corroborated by experiments in vivo and in vitro. Importantly, several derivatives of GGA have been synthesized that have improved pharmaco-chemical and HSPs-boosting properties. In this review, the current knowledge and potential cardioprotective mechanisms of GGA are summarized comprehensively. We discuss the protective effects of GGA in cardiovascular diseases and myocardial injury induced by physical or chemical injury. Currently available information suggests that GGA could be employed as a novel pharmacologic intervention against cardiovascular disease.

Topics: Animals; Anti-Arrhythmia Agents; Apoptosis; Arrhythmias, Cardiac; Cardiovascular Agents; Cardiovascular Diseases; Cardiovascular System; Diterpenes; Endothelium, Vascular; Heat-Shock Proteins; Humans; Insulin Resistance; Myocardium; Oxidative Stress; Treatment Outcome

Heat shock proteins (HSPs) are molecular chaperones with roles in longevity and muscular preservation. We aimed to show elevating HSP70 improves indices of health span. Aged C57/BL6 mice acclimated to a western diet were randomized into: geranylgeranylacetone (GGA)-treated (100 mg/kg/d), biweekly heat therapy (HT), or control. The GGA and HT are well-known pharmacological and environmental inducers of HSP70, respectively. Assessments before and after 8 weeks of treatment included glycemic endpoints, body composition, and muscular endurance, power, and perfusion. An HT mice had more than threefold, and GGA mice had a twofold greater HSP70 compared with control. Despite comparable body compositions, both treatment groups had significantly better insulin sensitivity and insulin signaling capacity. Compared with baseline, HT mice ran 23% longer than at study start, which was significantly more than GGA or control. Hanging ability (muscular endurance) also tended to be best preserved in HT mice. Muscle power, contractile force, capillary perfusion, and innervation were not different. Heat treatment has a clear benefit on muscular endurance, whereas HT and GGA both improved insulin sensitivity. Different effects may relate to muscle HSP70 levels. An HSP induction could be a promising approach for improving health span in the aged mice.

Topics: Animals; Body Composition; Diterpenes; Female; HSP70 Heat-Shock Proteins; Hyperthermia, Induced; Insulin Resistance; Mice; Mice, Inbred C57BL; Muscle Strength; Muscle, Skeletal; Physical Endurance; Random Allocation

Induction of heat shock protein (HSP)72 improves insulin resistance and obesity in diabetic animal models. Geranylgeranylacetone (GGA), known as an antiulcer drug, induces HSP72 and protects organs against several cellular stresses. This study investigated whether GGA administration would induce HSP72 in liver and render physiological protection against high-fat feeding in mice. A single and 4-wk oral administration of 200 mg/kg GGA was performed in high-fat diet (HFD)-fed mice. Metabolic parameters, cytokines, and gene expressions related to insulin signaling were evaluated. A single administration of GGA induced HSP72 in liver of normal chow-fed and HFD-fed mice. Insulin resistance after HFD was slightly ameliorated. Four weeks of GGA administration also increased HSP72 in liver and significantly improved insulin resistance and glucose homeostasis upon glucose challenge. Activation of c-jun NH₂-terminal kinase (JNK) was attenuated, and insulin signaling was improved in the liver of HFD mice. Visceral adiposity was decreased in GGA-treated mice, accompanied by reduced leptin and increased adiponectin levels. GGA can be a novel therapeutic approach to treat metabolic syndrome as well as type 2 diabetes by improving insulin signaling and reducing adiposity. These beneficial effects of GGA could be mediated through HSP72 induction and JNK inactivation in the liver.

Topics: Adiponectin; Animals; Area Under Curve; Blood Glucose; Body Weight; Diterpenes; Eating; Glucose Tolerance Test; HSP72 Heat-Shock Proteins; Insulin; Insulin Resistance; Intra-Abdominal Fat; Leptin; Liver; Male; Mice; Mice, Inbred C57BL; Signal Transduction

We investigated the effects of insulin resistance on the expression of heat-shock proteins (HSPs) and myocardial protection against ischemia/reperfusion injury. Male Sprague-Dawley rats received normal chow (CNT) or high-fat (HiF) diet. HiF diet for 6 weeks resulted in the development of insulin resistance, which was evaluated by oral glucose test and insulin tolerance test. Twenty-four hour after oral administration of geranylgeranylacetone (GGA) (200 mg/kg), the heart was isolated and perfused retrogradely with two different doses of insulin (0.1 or 1 mU/ml). Myocardial expression of HSP72 was examined using Western blot analysis. In the HiF group, the expression of HSP72 in response to GGA was decreased. The recovery of left ventricular developed pressure (LVDP) 30 min after reperfusion was tended to be lower in HiF group than in CNT group. Although GGA improved the recovery of LVDP in both CNT and HiF rats, LVDP during reperfusion period was significantly lower in HiF group than in CNT group. High-dose insulin perfusion caused deterioration of post-ischemic functional recovery and LVDP was not different between the two groups, but GGA-induced cardioprotection was preserved irrespective of the dose of insulin both in the CNT and HiF rats. This is the first demonstration that expression of HSP72 was depressed in the heart and that reduced HSP72 was related with less cardioprotection against ischemic insult in high-fat diet-induced insulin resistance rats.

Topics: Animals; Dietary Fats; Diterpenes; Glucose Tolerance Test; Heat-Shock Proteins; HSP72 Heat-Shock Proteins; Insulin; Insulin Resistance; Male; Myocardial Ischemia; Myocardial Reperfusion Injury; Rats; Rats, Sprague-Dawley