Biochemistry
Parinaz Hajiyousefipour; Mehdi Basaki; Davoud Kianifard; Yousef Panahi; Mehri Anisi
Abstract
Nicotine is a natural alkaloid and the primary cause of tobacco addiction. Nicotine stimulates the brain, raises blood pressure and heart rate, increases metabolic rate, suppresses appetite, and regulates body weight through binding to nicotinic acetylcholine receptors (nAChRs). Nicotine causes weight ...
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Nicotine is a natural alkaloid and the primary cause of tobacco addiction. Nicotine stimulates the brain, raises blood pressure and heart rate, increases metabolic rate, suppresses appetite, and regulates body weight through binding to nicotinic acetylcholine receptors (nAChRs). Nicotine causes weight loss, enzyme leakage, lipid peroxidation, and oxidative stress in the liver. To investigate the time-dependent effects of nicotine on liver function rats were injected intraperitoneally daily with of nicotine (2 mg/kg). Forty blood samples were taken at four stages, as four independent groups, before nicotine administration and 30 minutes, one week, and four weeks after the first nicotine administration. Serum glucose, albumin, urea, and uric acid were measured by standard methods. After four weeks of nicotine administration, liver samples were fixed in a 10% formaldehyde solution, and diameters of the central vein, hepatocyte, and sinusoid and thickness of the liver capsule were measured. Short and long-term nicotine administration decreased serum glucose and albumin. Serum urea and uric acid decreased following immediate, short-term, and long-term nicotine administration. Also, the diameter of hepatocytes and sinusoids increased after four weeks of nicotine administration. Nicotine reduces hepatic synthesis of glucose, albumin, urea, and uric acid time-dependently through various regulatory mechanisms. Investigating nicotine's effects on the genes and enzymes involved in liver metabolism will help to clarify the molecular mechanisms of nicotine's effects.
Animal physiology
Mehdi Basaki
Abstract
A review on hibernation was done by extensive search in main databases, using appropriate keywords and reading the newer and more cited articles from more reliable journals. This review investigated biochemical and molecular strategies of hibernating mammals to combat cold and lack of food and water. ...
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A review on hibernation was done by extensive search in main databases, using appropriate keywords and reading the newer and more cited articles from more reliable journals. This review investigated biochemical and molecular strategies of hibernating mammals to combat cold and lack of food and water. Growth and survival in times of resource scarcity require behavioral, physiological, cellular, and molecular adaptation in a relatively short time. Hibernation is a set of physiological strategies that allow animals to live in cold and lack food and water. Mammalian hibernation is a physiological state during which animals repeatedly experience periods of torpor and Interbout arousal. Hibernation varies in different kinds of animals. The inactive periods of heterotherms are more like deep sleep than hibernation. Voluntary hibernators enter a dormant period only when food resources are low, the weather is cold, and the season is changing. Obligate hibernations enter the inactive period seasonally, regardless of food availability, ambient temperature, and photoperiod. Obligate hibernating mammals can slow their metabolism, lower their body temperature, and fall into a torpor state. The energy supply is mainly made from fats stored pre-hibernation in this stage. This is associated with the upregulation of enzymes responsible for carbohydrate metabolism and the downregulation of enzymes responsible for fatty acid oxidation during hibernation. Non-stimulation of smell, taste, and oral-pharyngeal and digestive nerves and hormones such as leptin and insulin play a role in the neural suppression of feeding behavior from the hypothalamus. As water leaves the muscles, the plasma osmolality of hibernating animals decreases. Reducing blood osmolality acts as a thirst-suppression message to the brain. Hibernations are tolerant to cold both behaviorally and at the cellular level because the sensory neurons in these animals are less sensitive to cold. Also, hibernators have less cold-sensitive neurons in their hypothalamus. Hibernation is not simply a reduction in body temperature and vital parameters, but an active process that is seasonally regulated at the cellular and molecular levels. This seasonal adaptation is controlled by hormonal, neural, genetic, and epigenetic regulations. As different kinds of animals can hibernate, comparative studies are necessary to discover the central events of hibernation. What we have learned from the mechanism of animals hibernation can be used to develop methods to improve human health. Hibernation strategies can help reduce muscle and bone disuse atrophy, increase limb preservation time, fight obesity, and prevent reperfusion injury following myocardial infarction and stroke. Many questions about hibernation remain to be addressed in future research.
