Changes in α7β1 integrin signaling after eccentric exercise in heat-shocked rat soleus.

Introduction: α7β1 integrin links the extracellular matrix to the focal adhesion (FA) in skeletal muscle and serves as a stabilizing and signal relayer. Heat shock (HS) induces expression of proteins that interact with the FA.

Methods: Male Wistar rats were assigned to 1 of 3 groups: control (CON); eccentric exercise (EE); or EE+HS (HS).

SOD1-G93A mice exhibit muscle-fiber-type-specific decreases in glucose uptake in the absence of whole-body changes in metabolism.

Background: Skeletal muscles play an important role in systemic glucose homeostasis and are purported to be the origin of the altered metabolic state observed in amyotrophic lateral sclerosis (ALS).

Objective: The purpose of this study was to evaluate whole-body and muscle-specific glucose metabolism in the SOD1-G93A mouse model of ALS.

Methods: We assessed glucose tolerance in early-, middle-, and late-stage SOD1-G93A and control mice using an intraperitoneal glucose tolerance test.

Acute heat stress prior to downhill running may enhance skeletal muscle remodeling.

Heat shock proteins (HSPs) are chaperones that are known to have important roles in facilitating protein synthesis, protein assembly and cellular protection. While HSPs are known to be induced by damaging exercise, little is known about how HSPs actually mediate skeletal muscle adaption to exercise. The purpose of this study was to determine the effects of a heat shock pretreatment and the ensuing increase in HSP expression on early remodeling and signaling (2 and 48 h) events of the soleus (Sol) muscle following a bout of downhill running.

In vivo stimulation of oestrogen receptor α increases insulin-stimulated skeletal muscle glucose uptake.

Previous studies suggest oestrogen receptor α (ERα) is involved in oestrogen-mediated regulation of glucose metabolism and is critical for maintenance of whole body insulin action. Despite this, the effect of direct ERα modulation in insulin-responsive tissues is unknown. The purpose of the current study was to determine the impact of ERα activation, using the ER subtype-selective ligand propylpyrazoletriyl (PPT), on skeletal muscle glucose uptake.

Altered estrogen receptor expression in skeletal muscle and adipose tissue of female rats fed a high-fat diet.

Estrogen receptors (ERs) are expressed in adipose tissue and skeletal muscle, with potential implications for glucose metabolism and insulin signaling. Previous studies examining the role of ERs in glucose metabolism have primarily used knockout mouse models of ERα and ERβ, and it is unknown whether ER expression is altered in response to an obesity-inducing high-fat diet (HFD). The purpose of the current study was to determine whether modulation of glucose metabolism in response to a HFD in intact and ovariectomized (OVX) female rats is associated with alterations in ER expression.

Acute heat treatment improves insulin-stimulated glucose uptake in aged skeletal muscle.

Aging is associated with insulin resistance and decreased insulin-stimulated glucose uptake into skeletal muscle. Although the mechanisms underlying age-related insulin resistance are not clearly defined, impaired defense against inflammation and tissue oxidative stress are likely causes. Heat shock proteins (HSPs) have been shown to protect tissue from oxidative stress and inhibit the activation of stress kinases such as JNK, known to interfere with the insulin signaling pathway.

Neurodegeneration in an animal model of Parkinson's disease is exacerbated by a high-fat diet.

Despite numerous clinical studies supporting a link between type 2 diabetes (T2D) and Parkinson's disease (PD), the clinical literature remains equivocal. We, therefore, sought to address the relationship between insulin resistance and nigrostriatal dopamine (DA) in a preclinical animal model. High-fat feeding in rodents is an established model of insulin resistance, characterized by increased adiposity, systemic oxidative stress, and hyperglycemia.

Age-related changes in HSP25 expression in basal ganglia and cortex of F344/BN rats.

Normal aging is associated with chronic oxidative stress. In the basal ganglia, oxidative stress may contribute to the increased risk of Parkinson's disease in the elderly. Neurons are thought to actively utilize compensatory defense mechanisms, such as heat shock proteins (HSPs), to protect from persisting stress.

Lipoic acid increases heat shock protein expression and inhibits stress kinase activation to improve insulin signaling in skeletal muscle from high-fat-fed rats.

The antioxidant alpha-lipoic acid (LA) has been shown to improve insulin action in high-fat (HF)-fed animal models, yet little is known about its underlying mechanisms of action. We hypothesize that LA acts by inducing heat shock proteins (HSPs), which then inhibit stress kinases known to interfere with insulin signaling intermediates. Male Wistar rats were fed a HF diet (60% calories from fat) for 6 wk, while controls received a chow diet (10% calories from fat).

Heat treatment improves glucose tolerance and prevents skeletal muscle insulin resistance in rats fed a high-fat diet.

Objective: Heat treatment and overexpression of heat shock protein 72 (HSP72) have been shown to protect against high-fat diet-induced insulin resistance, but little is known about the underlying mechanism or the target tissue of HSP action. The purpose of this study is to determine whether in vivo heat treatment can prevent skeletal muscle insulin resistance.

Research Design And Methods: Male Wistar rats were fed a high-fat diet (60% calories from fat) for 12 weeks and received a lower-body heat treatment (41 degrees C for 20 min) once per week.

Age-related differences in skeletal muscle insulin signaling: the role of stress kinases and heat shock proteins.

Aging is associated with an increase in insulin resistance in skeletal muscle, yet the underlying mechanism is not well established. We hypothesize that with aging, a chronic increase in stress kinase activation, coupled with a decrease in oxidative capacity, leads to insulin resistance in skeletal muscle. In aged (24 mo old) and young (3 mo old) Fischer 344 rats, 2-deoxyglucose uptake and insulin signaling [as measured by phosphorylation of insulin receptor substrate-1 (IRS-1), Akt (protein kinase B), and Akt substrate of 160 kDa (AS160)] decreased significantly with age.