Trakia Journal of Sciences, Vol. 8, No 2, 2010 73 Trakia Journal of Sciences, Vol. 8, No 2, pp73-77, 2010 Copyright © 2009 Trakia University Available online at: http://www.uni-sz.bg ISSN 1313-7050 (print) ISSN 1313-3551 (online) Original Contribution MORPHOLOGY AND ULTRASONOGRAPHY OF THE PERICARDIAL AND EPICARDIAL ADIPOSE TISSUE IN HEALTHY RABBITS (Oryctolagus cuniculus) P. Yonkova 1* , D. Vladova 2 , R. Dimitrov 1 , А. Rusenov 3 , D. Zaprjanova 4 , P. Аtanassova 5 , M. Stefanov 2 1 Department of Veterinary Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria 2 Department of Morphology, Physiology and Nutrition of Animals, Faculty of Agriculture, Trakia University, Stara Zagora, Bulgaria 3 Department of Internal diseases, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria 4 Department of Pharmacology, Physiology of Animals and Physiological Chemistry, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria 5 Department of Anatomy, Histology and Embryology, Medical University, Plovdiv, Bulgaria ABSTRACT Rabbits develop a visceral type obesity and therefore is exceptionally suitable as a model for lipid metabolism investigation. Ten clinically healthy New Zealand White rabbits from both genders, weighing from 3.5 to 3.7 kg were used. The blood plasma concentrations of total cholesterol and triglycerides were 1.45 ± 0.15 mmol/L and 0.63 ± 0.01 mmol/L, respectively. The highest amount of pericardial adipose tissue was observed around the free surface of the right ventricle and the apex of the heart. The average mass of pericardial adipose tissue was 3.72 ± 0.24 g (0.1% of body weight and 47% of heart weight). By ultrasonography, pericardia adipose tissue was visualized as a moderately echoic homogeneous structure against the hyperechoic myocardium of the right ventricle. Its thickness was 3.2 ± 0.26 mm. The results of the present study showed that the rabbit was a suitable model for monitoring of quantitative changes in visceral fat depots in mammals, allowing their study in vivo by ultrasonography instead of utilizing dissection. Key words: rabbits, pericardial adipose tissue, epicardial adipose tissue, ultrasonography INTRODUCTION The New Zealand White rabbit belongs to average rabbit breeds (2–5 kg) bred for meat production. It is characterized with a rapid growth rate and is prone to deposition of large amounts of fat. Rabbits are small and relatively inexpensive models for research purposes (1, 2). The blood lipid profile in rabbits is similar to that in men. In this animal species, a central (visceral) type of obesity is developing, thus __________________________ *Correspondence to: Penka Yonkova Yonkova; Trakia University, Faculty of Veterinary Medicine, Department of Veterinary Anatomy, Histology and Embryology, Stara Zagora 6000, Bulgaria, tel. 00359 42699649; e-mail: pjon@abv.bg making it extremely appropriate for investigations on human lipid metabolism (3). The reference values of total blood cholesterol in rabbits according to (4) are between 0.14 and 1.86 mmol/L, and those of triglycerides: from 0.90 tо 1.55 mmol/L. (3) have established total cholesterol level of 1.99 mmol/L and triglycerides of 0.49 mmol/L in healthy male rabbits, and cholesterol values reported by (5) were between 0.90 and 1.4 mmol/L. In the thorax, the visceral adipose tissue is localized in the mediastinum and around the heart (6). The pericardial adipose tissue (PAT) is located on the parietal layer of the pericardium (7) covers about 80% of the heart