Stress hyperglycemia. The stress linked with criticalillness is characterized by alteration of hypothalamic–pituitary–adrenal(HPA) axis hormones, theautonomic nervous system, cytokines, and activationof immune-neuroendocrine axis,169,170 all in favorof hyperglycemia. Carbohydrates are usually the firstenergetic supply for various metabolic processes particularlyin cases of stress and tissue glycogen depletion.This stress causes release of adrenal hormonesvia stimulation of sympathetic nervous system duringstress leading to enhanced release of catecholamines,glucagon, and growth hormone, which furthermorepromote gluconeogenesis, glycogenolysis, and insulinresistance.171-179 On the other hand, it has been suggestedthat insulin release may be suppressed as aresult of enhanced activation of the pancreatic alphareceptors.180 The low insulin levels, together withinsulin resistance in the presence of increased secretionof the counter-regulatory hormones, results in akind of stress hyperglycemia. Inhibition of AChEactivity leads to activation of HPA axis and sympatheticautonomic nervous system, which consequentlyresult in hyperglycemia.181 Malathion decreasedhypothalamic corticotrophin releasing hormone in mRNA level that contributed to hypertriglyceridemia,carbohydrate metabolism, and diabetic form ofinsulin resistance, which are all associated withincreased levels of hypothalamic inducible nitricoxide (NO) synthase mRNA.182 Also, chlorpyrifos andmethoxychlor alter gonadotropin-releasing hormone(GnRH) biosynthesis in the hypothalamic cell line invitro, suggesting to have endocrine disrupting effectson GnRH neurons.183 Exposure to acephate and otherpesticides can increase plasma corticosterone anddeplete adrenal cholesterol content.36,184 Methyl parathionelevated plasma corticosterone concentration.44Malathion increased catecholamine and secretion ofglucocorticoids that provokes glycogenolysis and gluconeogenesis.82Plasma adrenocorticotropes hormone,corticosterone, and aldosterone levels were increasedby exposure to acephate and methamidophos. In fact,the effect of methamidophos on the adrenal cortex maybe mediated by the pituitary gland, while the effect ofacephate may be due to direct gland interaction.185 Followingcarbofuran exposure, the level of norepinephrineincreased in the olfactory bulbs, the telencephalichemispheres, and the hypothalamus. An increase in thelevel of dopamine was also found in hypothalamus.78Diazinon increased the synthesis of testosterone, causingchanges in carbohydrate metabolism.48 Fenitrothionblocked dihydrotestosterone-dependent androgenreceptor activity in human hepatoma cells.
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