Age-related changes of insulin receptors, plasma insulin and glucose level

Abstract

The effects of aging on hepatic and erythrocyte insulin receptors have been investigated in 6, 12, 18 and 21-months-old compare to 3-months-old rats. Plasma insulin was elevated in 6, 12 and 18-months-old rats. Specific binding of insulin in liver was increased at the age of 8 months and accompanied with increase in concentration of low affinity binding sites, while specific binding to erythrocytes as well as concentration of both classes of binding sites was increased in 6-months-old rats. The protein and mRNA content of hepatic receptor were decreased only in the oldest animals. Plasma glucose was elevated starting from 12-months-old rats, while, after decrease in 6-months-old animals, citrulline was raised in the oldest group. The results demonstrating that specific binding of insulin in liver and erythrocytes and the concentration of binding sites in both tissues were not decreased during aging, as well as the absence of changes in affinity of insulin binding sites do not point out to occurrence of insulin resistance. However, the increase in insulinemia in the middle of lifespan, elevated plasma glucose and citrulline as well as decrease of hepatic receptor protein and mRNA content in the oldest animals indicate some age-related changes in insulin signaling.

A metabolic and functional overview of brain aging linked to neurological disorders

“…4) leading to various health problem such as diabetes, cardiovascular complications, osteoporosis and others. Veiga et al (2004) have reviewed the changes in the sex hormones and brain aging, and the authors have discussed the role of these hormones in modulating neurotransmitter synthesis, neurotransmitter receptor expression and synaptic transmission and remodeling, emphasizing that the nervous system E estrogen, P progesterone is a target for sex hormones and a source of sex steroids (Korićanac et al 2004; Table 5). The physiological variations in the concentration of sex hormones could affect the insulin receptor action and their interaction with glucose, thereby altering the carbohydrate metabolism (Valdes et al 1991).…”

“…Morever, the brain insulin/IR signal transduction, beside the regulation of glucose metabolism, delivers signals necessary for synaptic activity and plasticity, of memory formation and for memory storage as well as for cell differentiation (Kremerskothen et al 2002). Recently insulin levels have been measured in aging and show a decrease with age (Korićanac et al 2004), insulin levels are also decreased in DM as well as experimental diabetes in animal models (Fulop et al 2003;Biessels et al 2002b;Taha et al, unpublished).…”

Pengaruh Pemberian Sari Buah Belimbing Wuluh (Averrhoa Bilimbi L.) Terhadap Kadar Glukosa Darah Tikus Sprague Dawley

“…Tikus mulai mengalami peningkatan kadar glukosa darah setelah memasuki usia 12 minggu. 21 Peningkatan usia akan berpengaruh terhadap fungsi organ, salah satunya adalah sel beta pankreas. Sel beta pankreas semakin lama akan mengalami degradasi sehingga dapat menyebabkan penurunan hormon insulin yang dihasilkan.…”

Biogerontology in Serbia

“…Although insulin participates in regulation of hepatic gluconeogenesis, the role which changes in hepatic insulin receptor (IR) play in genesis of age-related insulin resistance is contraversial (Fulop et al 2003). Korićanac et al (2004) demonstrated no decrease in specific binding of insulin in liver and erythrocytes, or the concentration of binding sites in both tissues during aging. However, the increase in insulinemia, elevated plasma glucose level and NO level, as well as the decrease of hepatic receptor protein and mRNA content in the oldest rats, indicate some age-related changes in insulin signaling.…”