Coronary arteriosclerosis in dogfish (Scyliorhinus canicula). An assessment of some potential risk factors.

Abstract

Coronary myointimal lesions are described in the dogfish (Scyliorhinus canicula). These lesions are similar to those previously described in salmonids and are characterized by breaks in and disappearance of the inner elastic layer and intimal thickening as a result of inclusions of fibers and smooth muscle cells. Lesions are associated with all the branching points in the main subepicardial conal coronary arteries that supply the heart Intimal thickenings were rare in other parts of these arteries. However, we found extensive lesions unassociated with branching points in two main intramyocardial ventricular arteries that supply the ventricular spongy myocardium. We carried out a statistical study of the incidence and severity of these intramyocardial lesions in relation to several potential risk factors. Intimal thickenings were present in 90.5% of the fish specimens and 40% of the histological sections. Sex, reproductive stage, plasma triacylglycerol, and cholesterol (total and related to high-density lipoproteins) were not significantly related to either the incidence or severity of lesions. Total fish length was significantly correlated with the lesion severity index (r=0J3,p<0.01). We also found significant differences in incidence related to the location of lesions. The middle areas of the intramyocardial branches, very close to the atrioventricular canal, were more affected than the cranial and caudal areas. The dorsal and ventral artery walls were also more affected than the lateral ones. The preferential location of the lesions in areas presumably subjected to mechanical stress because of a bifurcating bloodstream or the pulsatile flow throughout the atrioventricular canal suggests that coronary arteriosclerosis in dogfish is an age-related process, with hemodynamic factors playing a primary or secondary pathogenetic role. This disease seems not to be related to some factors suggested for salmonids, such as reproductive cycle, anadromous migration, river pollution, or plasma lipid concentration. Several pathogenetic factors have been suggested. Since this disease was discovered and extensively studied in salmonids, physiological stress related to anadromous migration involving increased plasma 17-hydroxycorticosteroids has been proposed as a main causal Received June 11, 1992; revision accepted February 25, 1993. mechanism. 111 Other factors associated with developing coronary arteriosclerosis are alteration in sex hormone status during maturation, 712 environmental mutagens and poisons, 89 and high levels of apolipoprotein B (apo B)-containing lipoprotein, either spontaneous 13 or induced by diet. 1415 It is uncertain whether some of these associations can be considered cause-and-effect relations.Hemodynamic factors have only recently been considered in fish coronary arteriosclerosis. The reported absence of coronary arterial lesions in five species of elasmobranchs in relation to their high prevalence in salmonids has been attributed to the mechanical stress produced in the coronary artery of the ...

Naturally occurring lesions and micro‐organisms in two species of free‐living sharks: the spiny dogfish, Squalus acanthias L., and the smooth dogfish, Mustelus canis (Mitchill), from the north‐western Atlantic

“…Another study of 39 specimens of five different elasmobranchs failed to document coronary arterial lesions (Farrell, Davie & Sparksman 1992). The finding of coronary arteriosclerotic lesions predominantly in M. canis in this study, and the absence of myocardial pathology further support the hypothesis of species‐specific causal relationships suggested by García‐Garrido et al . (1993).…”

Introduction and comparison of two methods of assessment of coronary lesions in Atlantic salmon, Salmo salar L.

“…Coronary arteries on the ventral surface of the bulbus arteriosus, rostrally to the major bifurcation, the predilected site for arteriosclerosis in salmonids (Robertson, Wexler & Miller 1961; Moore et al. 1976a,b; Garcia‐Garrido, Muñoz‐Chápuli & de Andrés 1993), were examined.…”

Intimal thickening of coronary arteries in the rabbitfish, Chimaera monstrosa L. (Chondrichthyes: Holocephali)

“…Intimal thickening of coronary arteries in teleosts has been repeatedly reported since Robertson, Wexler & Miller (1961) described its occurrence in the Pacific salmon, Oncorhynchus tshawytscha (Walbaum). The tissue changes are characterized by (1) thinning, breaking, or replication of the inner elastic lamina, (2) focal intimal cellular proliferation , and (3) increase in collagen and elastic fibres with no evidence of lipid deposition (see review by García‐Garrido, Muñoz‐Chápuli & De Andrés 1993). The endothelial layer often remains intact, whereas the media becomes thinner, with disruption of the muscle fibres.…”