| Objective:The experiment is to study the influence ofβ2-agonist formoterol on cancer cachexia by establishing an experimental cancer cachectic model,observing the influence on condition,removed tumor weight,metabolism indicators,serum cytokine,survival time and the regulation of myostatin in skeletal muscle.Studying the mechanism of formoterol in anticachectic effects in the early stage.Methods:82 healthy BALB/c mice were randomized into 5 groups:healthy control group(HC) 10,cancer cachexia with physiologic solution group(CC) 18,cancer cachexia with Medroxyprogesterone group(MPA)18,cancer cachexia with prophylactic group(PG)18,cancer cachexia with Formoterol group(FG)18."CC"group,"MPA"group,"PG"groupand" FG"group received a inoculum of colon26 cells on right armpit to establish cancer cachexia model."HC"group received a corresponding volume of physiologic solution.8 mice were randomized selected from "CC"group,"MPA"group,"PG"group,and "FG"group were used to observe survival time.3-5 days later,the tumor could be touched in each tumor bearing group ."PG "group being administered a daily intraperitoneal dose of formoterol (2mg/kg body weight).On the 15th day, the other tumor bearing mice got into cancer cachexia."FG"group being administered a daily intraperitoneal dose of formoterol (2mg/kg body weight),"CC"group administered a corresponding intraperitoneal dose of physiologic solution."MPA"group theraped with Medroxyprogesterone (120mg/kg body weight/day).All groups were treated one week later,the animal were killed and collected tissue and serum.The rest mice which to observe survival time had daily drug therapy and write down the survival time.The serum levels of biochemical indicators were measured by omni-automatic biochemistry analyzer. The serum levels of cytokine TNF-αand IGF-1 were measured by RIA. The atrophy of gastrocnemius was observed by optical microscope.The expression of myostatin in gastrocnemius was investigated by immunohistochemistry.The differences in all indicators of each group were observed and contrasted. All data were analyzed with the spss13.0 software and expressed by ( x±s), the comparison among multitude simple mean by One-Way analysis of variance (One-Way ANOVA).Results:1 Animal model:The tumor could be touched on the tumor bearing mice when received inoculum of tumor cell 3-5 days later. The general condition had no obviously change.All tumor bearing mice got into cancer cachexia characterized coarse fur, anorexia and weight decreased more than 10% 15 days later.2The condition and removed tumor weight : In the begining,the body weight of each group had no notable difference (Ρ>0.05).15 days after tumor bearing,the mice in"CC"group had least food intake and worst condition.The food intake in "MPA"group,"PG"group and "FP"group was more than "CC"group ( P<0.05 ) .The last removed tumor weight in"MPA"group,"PG"group and "FG"group was higher than in"CC"group ( P<0.05 ) ;the last removed tumor weight in"PG"group was higher than in "MPA"group and "FG"group;the last tumor removed weight in "FG"was higher than in"MPA"group,with no significant difference(Ρ>0.05).3 Biochemical indicators:All tumor bearing mice were characterized by metabolic disorders.The glucose in "CC"group was lower than other groups(P<0.05);with drug intervened,the serum level of glucose in"MPA"group,"PG"group and "FG"group was higher than in "CC"group,with no significant difference(P>0.05);there was significant difference of the serum level of cholesterol between "MPA"group and"CC"group(P<0.05);there was no significant difference of the serum level total protein between "CC"group and "HC"group(P>0.05);the serum level of total protein in all tumor bearing mice and "HC"group has no significant difference(P>0.05).4 Cytokines:The serum level of TNF-αin each tumor bearing mice group was higher than in "HC"group;with drug intervened,the serum level of TNF-αin"MPA"group,"PG"gorup and "FG"group was lower obviously than in "CC"group(P<0.05);the serum level of TNF-αin "PG"group was lower than in "MPA"(P<0.05);the serum level of TNF-αin "FG"group was lower than in "MPA"group with no significant difference(P>0.05);the serum level of TNF-αin "PG"group was obviously lower than in "FG"group(P<0.05).The serum level of IGF-1 in each tumor bearing mice group was lower than in "HC"group(P<0.05);with drug intervened,there was no significant difference of the serum level of IGF-1 between each tumor bearing mice group and "HC"group (P>0.05).5The wet weight of grastrocnemius:The wet weight of gastrocnemius in each tumor bearing mice group was lower obviously than "HC"group(P<0.05);the wet weight of grastrocnemius in "PG"group and "FG"group was higher than "MPA"group and "CC"group(P<0.05);the wet weight of grastrocnemius in "PG"group was higher obviously than in "FG"group(P<0.05);there was no obviously difference of the wet weight of grastrocnemius between "CC"group and "MPA"group(P>0.05).6The atrophy of grastrocnemius observed by optical microscope:All tumor bearing mice characterized variable degrees of atrophy.The maximum cross sectional diameter in grastrocnemius of each tumor bearing group was shorter than in "HC"group(P<0.05);with drug intervened,the maximum diameter in "PG"group and "FG"group was longer obviously than "CC"group and "MPA"group(P<0.05);the maximum diameter in "PG"group was obviously longer than in "FG"group(P<0.05);there was no significant difference of maximum diameter between "CC"group and "MPA"grouop (P>0.05).7The activity of myostatin in grastrocnemius:The activity of myostatin in grastrocnemius in each tumor bearing group was more strengthened than in "HC"group(P<0.05);"CC"group was the most strenghtened;with drug intervened,the activity of myostatin in grastrcnemius in "PG"grouop and "FG"group was weaker than in "CC"group(P<0.05);there was no significant difference in activity of myostatin in grastracnemius between "MPA"group and "CC"group(P>0.05);the activity of myostatin in grastracnemius in "PG"group was weaker than in"FG"group,with significant difference(P<0.05).8The survival time:With drug intervened,the survival time in "MPA"group,"PG "group and "FG"group was longer than "CC"group(P<0.05);the survival time of "CC"group,"MPA"group,"PG"groupand"FG"groupwas23.38days,26.13days,26.25days and 28.50days;the survival time between "MPA"group and "PG"group had no difference(P>0.05);the survival time in "FG"group was longer than in "PG"group(P<0.05).Conclusions:1The study had successfully established an experimental animal model .Carcinoma cell caused in the host rapid loss of body weight gradually,particularly in skeletal muscle. This model provides contribution to study the mechanism of skeletal muscle depletion in cancer cachexia and the prevention and cure of cancer cachexia in the early stage.2In cancer cachectic model, there were cytokine disorder such as TNF-αand IGF-1.TNF-αhad an important role in the mechanism of cancer cachexia; with drug intervened,the serum level of IGF-1 had no significant changed.3Medroxyprogesterone increased the last tumor removed weight ,lowed the serum level of TNF-αand regulated the metabolic disorders.However,it had no effect on skeletal muscle.4Asβ2-agonist,formoterol atagonized the skeletal muscle depletion to take anticachectic effects. However,formoterol had no effect on metabolic disorders.With different mechanism compared to medroxyprogesterone,mice intervened with formoterol resulted in an reversal of the grastrocnemius muscle-wasting process.Formoterol increased the last tumor removed weight .5Myostatin,secreted from skeletal muscle in cancer cachexia ,up-regulated ubiquitin related genes to proteolysis in skeletal muscle. On the regulation of myostatin, the study indicatedβ2-agonist as a potential therapeutic tool in the early stage of cancer cachexia.6Both medroxyprogesterone and formoterol prolonged the survival time of cancer cachectic mice;preventive use of formoterol in prolong the survival time was the weakest. |
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