The incidence of diabetes mellitus is increasing among companion animals. This disease has similar characteristics in both humans and animals. Diabetes is frequently identified as an independent risk factor for infections associated with increased mortality. In the present study, homozygous diabetic (db/db) mice were infected with Listeria (L.) monocytogenes and then treated with the anti-diabetic drug exendin-4, a glucagon-like peptide 1 analogue. In aged db/db mice, decreased CD11b+ macrophage populations with higher lipid content and lower phagocytic activity were observed. Exendin-4 lowered high lipid levels and enhanced phagocytosis in macrophages from db/db mice infected with L. monocytogenes. Exendin-4 also ameliorated obesity and hyperglycemia, and improved ex vivo bacteria clearance by macrophages in the animals. Liver histology examined during L. monocytogenes infection indicated that abscess formation was much milder in exendin-4-treated db/db mice than in the control animals. Moreover, mechanistic studies demonstrated that expression of ATP binding cassette transporter 1, a sterol transporter, was higher in macrophages isolated from the exendin-4-treated db/db mice. Overall, our results suggest that exendin-4 decreases the risk of infection in diabetic animals by modifying the interaction between intracellular lipids and phagocytic macrophages.
ATP-Binding Cassette Transporters/metabolism ; Age Factors ; Animals ; Blood Chemical Analysis ; Cholesterol/metabolism ; Diabetes Mellitus, Type 2/*drug therapy/genetics ; Dyslipidemias/drug therapy/genetics ; Female ; Hyperglycemia/drug therapy/genetics ; Hypoglycemic Agents/*therapeutic use ; Injections, Intraperitoneal ; *Lipid Metabolism/drug effects ; Listeria monocytogenes/*drug effects/immunology ; Listeriosis/*drug therapy/immunology/microbiology ; Macrophages/drug effects/*metabolism ; Mice ; Obesity/drug therapy/genetics ; Peptides/*therapeutic use ; Phagocytosis/drug effects ; Venoms/*therapeutic use

OBJECTIVETo study the regulatory effect of lipi tiaozhi capsule (LTC) on the expression of peroxisome proliferator-activated receptor (PPAR) alpha and gamma mRNA in dyslipidemia rats and ApoE(-/-) mice, and to explore its mechanisms for regulating lipid metabolism. Methods 48 Wistar rats were randomly divided into the blank group, the model group, the treatment group (treated by LTC), and the control group (treated by Xuezhi-kang Capsule). After four-week modeling (except the blank group) 30 ApoE(-/-) mice were randomly divided into the blank group, the treatment group, and the control group. LTC was given by gastrogavage to rats and ApoE(-/-) mice in LTC groups while XZKC was given to XZKC groups. The medication was conducted once daily for eight weeks. The serum TC and TG contents of rats and mice were determined by enzymic method. The serum high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were detected by precipitation method. PPARalpha and gamma mRNA expressions were detected in the liver tissue of the rats and mice by fluorescent PCR.

RESULTSCompared with the model group and the blank group, the serum contents of TC, TG, and LDL-C of rats or mice in the treatment group decreased significantly (P < 0.01). The serum content of HDL-C increased significantly (P < 0.01). PPARalpha and gamma mRNA expressions of rats or mice increased significantly (P < 0.01). Compared with the control group, the serum contents of TC, TG, and LDL-C of mice and rats in the treatment group decreased (all P < 0.05), the serum content of HDL-C increased significantly (P < 0.05, P < 0.01). And PPARalpha and gamma mRNA expressions of rats or mice increased significantly (P < 0.05).

CONCLUSIONLTC could significantly increase PPARa and y mRNA expressions of experimental dyslipidemia rats and ApoE(-/-) mice, playing roles in regulating nuclear factors and further effecting lipid metabolism.

Animals ; Apolipoproteins E ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Dyslipidemias ; drug therapy ; metabolism ; Male ; Mice ; Mice, Knockout ; Peroxisome Proliferator-Activated Receptors ; genetics ; metabolism ; Phytotherapy ; RNA, Messenger ; genetics ; Rats ; Rats, Wistar