Sodium pentobarbital dosages for exsanguination affect biochemical, molecular and histological measurements in rats

Abstract

Rodents are widely used for animal research in Egypt. Pentobarbital is the most common anesthetic agent; however overdoses may affect the experimental outcomes and limit the use of tissues. To investigate the effects of sodium pentobarbital overdoses during exsanguination, three groups (6 rats/ group) of male and female rats were injected i.p. with 50, 100 and 150 mg/kg of sodium pentobarbital, then carotid exsanguination was performed immediately after loss of consciousness. Hypoxiainducible factor 1-alpha (Hif1a) and tumor necrosis factor-alpha (Tnfa) mRNA expressions in liver and kidney organs were evaluated. As well as, serum aminotransferase activities (AST&ALT), glucose, urea, creatinine, malondialdehyde (MDA), reduced glutathione (GSH) and catalase (CAT) levels were determined. The histological alterations in liver, kidney and spleen were studied. It was found that Hif1a and Tnfa were significantly overexpressed in the studied organs and serum AST, glucose, creatinine and urea levels were significantly increased after sodium pentobarbital overdoses (100 and 150 mg/kg) compared to 50 mg/kg dose. Similarly, significant increase in MDA and GSH levels of liver, kidney and spleen were noticed. Results showed gender difference where Hif1a and Tnfa levels were significantly overexpressed at high dose of sodium pentobarbital of liver and kidney organs in female more than male rats. Since euthanasia protocol may influence the physiological variables and affect genes' expression, it is recommended to avoid sodium pentobarbital overdose during euthanasia as it may interfere with the biochemical, molecular and histological measurements. In Egypt, rodents are considered the first choice for the majority of animal research and training. Euthanasia of animals is generally performed upon completion of the study or if a humane endpoint has been reached. Last updates of the Canadian Council on Animal Care (CCAC) and American Veterinary Medical Association (AVMA) euthanasia guidelines 1 describe several techniques for successful euthanasia to refine killing methods for rats and other laboratory animals 2. Euthanasia procedures are divided into two main methods; chemical and physical. Ideally, a mechanical method, such as exsanguination, should be implemented after the chemical death. Pentobarbital is an anesthetic agent commonly used in euthanasia. Olsen and Li (2011) reported that sodium pentobarbital is an injectable, fast-acting, central nervous system depressant which acts via GABA receptors to cause a loss of consciousness and cardiovascular depression 3. In the AVMA Guidelines, anesthetic overdose is recommended as an acceptable method of euthanasia. For rodents, overdose of sodium pentobarbital is the most preferable euthanizing agent 4-6. The main reported negative side effects of pentobarbital mono-anesthesia are cardiovascular and respiratory systems depression, decreased arterial blood pressure, peripheral vasodilation, decreased cardiac output and depression of the vasopressor response to hemorrhage 7. Moreover, ...

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