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Alterations of the vessel wall innervation during diabetes mellitus
K Lovasova1, D Kluchova, S Rybarova
1Department of Anatomy, Faculty of Medicine, Safarikiensis University, Kosice, Slovakia. lovask@pobox.sk
Insights
Diabetes mellitus (DM) alters rat mitral valve vessels, causing dilatation. Nerve fibers in the valve show no nitric oxide synthase activity, suggesting metabolic changes impact neurotransmission.
Area of Science:
- Cardiovascular Pathology
- Diabetology
- Neurohistochemistry
Background:
- Diabetes mellitus (DM) significantly increases cardiovascular morbidity and mortality, particularly affecting coronary and valvular heart disease.
- The neural structures within heart valves remain understudied in various pathological conditions, including diabetes.
Purpose of the Study:
- To investigate morphological alterations in the anterior cusp of the rat mitral valve's vasculature during experimental diabetes mellitus.
- To identify the presence and localization of nerve fibers and nitric oxide synthase (NOS) activity in the mitral valve's anterior cusp under diabetic conditions.
Main Methods:
- A histochemical method utilizing NADPH-diaphorase (NADPH-d) staining was employed to detect indirect nitric oxide synthase (NOS) activity.
- Vessels, including arterioles and capillaries, and perivascular nerve fibers in the tunica adventitia of the anterior mitral valve cusp were examined in control and diabetic rats.
Main Results:
- Morphological alterations, specifically marked dilatation of vessels, were observed in the anterior mitral valve cusp of rats with 8-12 weeks of diabetes compared to controls.
- Arterioles and fine capillaries were identified in the attachment zone, with perivascular nerve fibers present in the tunica adventitia.
- No NADPH-diaphorase positive nerve fibers were detected in the tunica adventitia of the mitral valve cusp in either control or diabetic rats.
Conclusions:
- Experimental diabetes mellitus induces significant vascular dilatation in the anterior mitral valve cusp of rats.
- The absence of NADPH-d positive nerve fibers suggests that alterations in nitric oxide (NO) neurotransmission during diabetes may involve mechanisms beyond direct NOS activity in perivascular nerves.
- Metabolic changes associated with diabetes likely lead to altered NO neurotransmission, potentially through excessive NOS production (e.g., endothelial eNOS) in the vessel walls.
Abstract:
Coronary and valvular heart disease during diabetes mellitus (DM) are major contributors of morbidity and mortality in the diabetic population. Relatively little atention has been given to the study of heart valve nerve structures in different pathological processes. In this study we have demonstrated the presence of possible morphological alterations in vessels of the anterior cusp of the rat mitral valve during 8-12 weeks DM. A histochemical method was used for the detection of NADPH-diaphorase (NADPH-d), which is the indirect NO-synthase marker. Arterioles and fine capillaries were localized in the attachment zone of the anterior cusp. Perivascular nerve fibres were identified running in the tunica adventitia. A marked dilatation of the vessels was seen in diabetes in comparison with control samples. No NADPH-d positive nerve fibres were observed in the tunica adventitia. It can be presumed that metabolic changes in the vessel walls during DM reflect modified neurotransmission of NO by means of their excessive overproduction of NOS (endothelial--eNOS) in endothelial cells. (Fig. 6, Ref. 32.).