كليدواژه :
انسولين , زايلازين , گلوكز , متابوليسم
چكيده فارسي :
زمينه مطالعاتي: زايلازين به عنوان داروي بي هوشي و مسكن در جراحي به طور وسيعي در انسان و دام مورد استفاده قرار مي گيرد.
هدف: مطالعه حاضر به منظور بررسي تاثير تزريق زايلازين بر متابوليسم گاو شيري هنگام تغيير برخي از متابوليت هاي خوني بود.
روش كار: در اين مطالعه از تعداد 24 راس گاو هلشتاين با شكم زايش 0/1 ± 3/5 و 0/3 ± 28 (Mean ± SD) هفته شيردهي استفاده شد. تيمارها شامل تزريق انسولين (6 n= ؛ HypoG)، انسولين و گلوكز (5 n= ؛ EuG)، بتاهيدروكسي بوتيرات (5n= ؛ HyperB) و محلول نمكي 0/9% (8 n= ؛ Control) بوده كه به مدت 56 ساعت انجام پذيرفت. در ساعت چهل و هفتم آزمايش، زايلازين (16 ميكروگرم بر كيلوگرم وزن بدن) تزريق گرديد. نمونه خوني قبل از تزريق (ساعت صفر) و يك ساعت بعد از تزريق زايلازين گرفتهشد. تفاوت تغيير متابوليت ها با استفاده از رويه GLM و تفاوت بين غلظت متابوليت ها و هورمون ها قبل و بعد از تزريق زايلازين در داخل هر يك از گروه ها و بين تيمارهاي مختلف با استفاده از رويه Mixed نرم افزار آماري SAS ارزيابي آماري گرديد. داده ها به صورت Mean ± SEM بيان گرديد.
نتايج: زايلازين سبب افزايش غلظت گلوكز خون در گروه كنترل و HyperB گرديد. در همه گروه ها به استثناي HypoG غلظت اسيدهاي چرب كاهش يافت. غلظت بتاهيدروكسي بوتيرات و هورمون هاي انسولين و گلوكاگون تغييري نكرد ولي در گروه HypoG افزايش غلظت انسولين مشاهده شد. كاهش غلظت هورمون كورتيزول در همه گروه ها به استثناي HypoG مشاهده شد.
نتيجه گيري نهايي: تاثير زايلازين در زمان تغيير متابوليت ها متفاوت مي باشد. عدم تغيير غلظت گلوكز در گروه هايي كه انسولين دريافت كرده بودند ناشي از اثر ممانعت كنندگي انسولين بر افزايش غلظت گلوكز بود. با توجه به افزايش غلظت گلوكز در دو گروه از دام ها بدون تغيير در هورمون هاي انسولين و گلوكاگون، استنباط مي شود كه علاوه بر تنظيمات هورموني مكانيسم هاي ديگري نيز در تنظيم گلوكز دخالت دارند.
چكيده لاتين :
Introduction: Xylazine is widely used in human and animal for different purposes such as anesthetics and analgesics in surgery. This component induces sedative, muscle relaxation and analgesic in veterinary. Xylazine is a α-2 agonist which causes cardiovascular and respiratory problem in animals. There is evidence that xylazine injection changed metabolites and endocrine in different species.
In early lactation, the onset of copious milk production would bring about hepatic metabolic overloud to meet the energy and nutrient requirements for milk production. Elevation of energy and nutrient requirements for maintenance and milk synthesis cannot fulfill the feed intake, which consequently causes a negative energy balance (NEB) in early lactation in dairy cows. During a NEB, low plasma glucose concentrations are observed, while concomitantly concentrations of plasma free fatty acids (FFA) and subsequently ketone bodies are increased. Our earlier studies confirmed that manipulated insulin, glucose, and BHB concentrations, through infusion, changed plasma metabolites and endocrine in mid-lactating dairy cows, affected systemic/ local mammary metabolism, and immune response of the mammary gland.
Based on our previous results and proved effects of xylazine injection on metabolism, this study aimed to assess the effects of xylazine injection on dairy cow metabolism alongside the change in some of blood metabolites and endocrine.
Material and methods: The study was carried out on 24 clinically healthy multiparous (3.5 ± 0.10) Holstein dairy cows at 28 ± 0.3 (MEAN ± SD) wks in milk. Cows were free of mastitis throughout the experimental period. Animals were housed in tie stalls two weeks before the start of experiment as adaptation period. Animals were fed ad libitum with good quality hay, an addition protein- and energy-rich concentrate fed to them according to their energy and protein requirements twice daily. They received minerals (50 g/ cow) per day. Fresh water was available entire the experimental period. The cows were milked twice a day at 0530 h and 1600 h. Treatment infusion includs: an insulin infusion to induce hypoglycemia (2.5 ± 0.1 mmol/L; HypoG, n=5), an insulin combined glucose infusion to study effects of sole insulin at concurrently normal glucose concentration (EuG, n=6), a Na-DL-β-OH-butyrate to obtain plasma BHBA concentration between 1.5 to 2.0 mmol/L (HyperB, n=5) comparable to those in spontaneous hyper ketonemia (above 1.2 mmol/L), and a 0.9 % NaCl infusion (NaCl, 20 mL/h) as control group (n=8).
On day before the start of infusion two indwelling intravenous catheters (Cavafix® Certo® Splittocan®, B. Braun Melsung AG, Germany) with a length of 32 cm and a diameter of 16 G were fixed in both jugular veins. The clamped infusions (56 h) started at 0900 am day one and continued to 0500 pm two days later. AS reported earlier (Kreipe et al. 2011; Vernay et al. 2012; Zarrin et al. 2013, 2014a,b) this study divided to two parts include: 48 h metabolites infusion to investigate the effects of manipulated metabolites concentration on metabolism and immune responses to metabolites infusion, and an addition 8 h to challenge mammary gland with lipopolysaccharide of E.coli (LPS) to investigate immune response simultaneously whit metabolite changing in dairy cows. At 47 h of infusion (1 h) before the intra-mammary LPS challenge to obtain mammary biopsies, a single dose of xylazine (16 μg/kg of BW) was injected. Blood samples were taken before (0 time) and 1 h after the xylazine injection. Plasma metabolites concentrations were measured enzymatically by commercial kits. Plasma insulin was measured by radioimmunoassay (RIA), and plasma glucagon concentrations were measured by using a commercial RIA kit. Changes of metabolites were evaluated by GLM procedure of SAS. Differences in plasma metabolites and endocrine parameters between before and after xylazine injection and between treatments were evaluated using the MIXED procedure of SAS with time points (0 and 1 h) and treatments (EuG, HyperB, HypoG, and Control) as fixed effects. Value presented as Mean ± SEM.
Results and discussion: As expected, plasma glucose concentrations decreased before xylazine injection (2.25 ± 0.1 mmol/L; P< 0.01) in HypoG group, which it was lower than other infusion groups (Kreipe et al. 2011; Zarrin et al. 2013). Xylazine injection increased plasma glucose concentrations in Control and HyperB groups (P< 0.05), which confirmed previous reported (Fayed et al. 1989; Okwudili et al. 2014). No change of plasma glucose concentration observed in HypoG and EuG groups, which can be explained by inhibitory effect of insulin on glucose concentration (Kreipe et al. 2011). In current study, xylazine injection did not changed plasma insulin concentrations, just an increase of insulin concentration observed in HypoG group, which can be explained by adjusted insulin infusion in this group to induced hypoglycemia. Glucagon concentrations did not react to xylazin injection in all treatment groups. In agreement with other researcher a decline of cortisol concentrations was observed in all treatment groups except HypoG (Sanhouri et al. 1992; Okwudili et al. 2014). Free fatty acids decreased in all treatment groups except HypoG, that this finding confirmed Ambrisko and Hikasa (2002) report. No change of beta-hydroxybutyrate concentrations observed between before and after xylazine injection in infusion groups.
Conclusion: The xylazine effects are different during the change of metabolites. Unchanged glucose concentration in HypoG and EuG is due to inhibitory effect of insulin on glucose elevation. Considering increasing glucose concentration in two animal groups without change in insulin and glucagon concentration, it can be speculated that other mechanisms than endocrine regulation contributes to glucose homeostasis.
