ENDOCARDIOSIS OF VALVULAR COMPLEX IN AGING STURGEONS (Acipenser SPP.): FIRST REPORT

Valvular endocardiosis is a degenerative process characterized by matrix proliferation and degeneration affecting cardiac valves. It is a common age-related lesion in animal and human species [1,2,3]. A limited documentation of fish valvular lesions is available [4] and to date no data have been reported on Acipenser species. The adult sturgeon heart is formed by sinus venosus, atrium, ventricle and outflow tract (conus arteriosus and bulbus arteriosus). Valve systems appear at the sinoatrial and atrioventricular junctions and in the conus arteriosus [5,6]. The present study represents the first description of morphological features of valvular endocardiosis in Acipenser spp. A total of 54 specimens of Acipenser spp. were collected in an italian fish farm and divided into three groups according to age and body weight: group 1 (G-1), 2-5 years, 0.5-2 kg, male, A. baerii and A. transmontanus (13 animals), ; group 2 (G-2), 6-10 years, 6-9 kg, A. baerii (5 male), A. transmontanus (6 female); group 3 (G-3), 12-16 years, 27-60 kg, female, A. gueldenstatedtii and A. transmontanus, 30 animals. Hearts were fixed in 10% buffered formalin solution and submitted to macroscopical evaluation. Samples of valve systems were processed for histological evaluation, embedded in paraffin and stained with Haematoxylin & Eosin, Weigert Van Gieson, Toluidine Blue and Alcian Blue stains. Valves lesions were scored on a 0 to 3 scale on the basis of the severity. Data were analyzed by Shapiro-Wilk normality test and Mann-Whitney U test (P<0.05) by means of GraphPad Prism® software. Valvular endocardiosis affected all the animals of the group 3. Particularly severe lesions characterized by verrucous proliferation with distortion of the valves and increase of myxomatoid Alcian positive matrix affected the valves at the bulboventricular junction. Fish of the group 1 and 2 generally showed no endocardiosis or low grade lesions; in particular atrioventricular valves were always less affected. All valves of group 3 showed a statistically significant increase of severity. The presence of most severe lesions in aged animals permits to consider endocardiosis an age-related lesion as observed in other species. A systematic study on a larger number of young fish is ongoing to confirm these preliminary results. [1] Aupperle H., Disatian S. Pathology, protein expression and signaling in myxomatous mitral valve degeneration: comparison of dogs and humans. J Vet Cardiol, 14:59-71, 2012; [2] Castagnaro M. et al. Mophological and biochemical invetigsations of mitral valve endocardiosis in pigs. Res Vet Sci, 62:121-125, 1997; [3] Donnelly KB. Cardiac valvular pathology: comparative pathology and animal models of acquired cardiac valvular diseases. Toxicol Pathol 36:204-217, 2008; [4 ]Cooper TK., Spitsbergen JM. Valvular and mural endocardiosis in aging zebrafish (Danio rerio). Vet Path. 52:504- 509,2016; [5] Burggren WW., Keller BB. Development of cardiovascular systems. Molecules to organisms. Cambridge University Press, New York 1997; [6] Icardo JM. et al. The structure of the conus arteriosus of the sturgeon (Acipenser naccarii) heart. I and II. Anat Rec 267:17– 27; 268:388– 398, 2002.