PECULIARITIES OF MORPHOFUNCTIONAL CHANGES OF MASTICATORY MUSCLES IN IODINE-DEFICIENT CONDITIONS

Abstract

The problem of iodine deficiency is becoming increasingly important in Ukraine. According to the United Nations Children’s Fund (UNICEF), each and all regions of Ukraine suffer from “hidden hunger”. The World Health Assembly has stated that the elimination of iodine deficiency will be as much a triumph for health care system as the eradication of smallpox and poliomyelitis. The goal of this study was to establish the peculiarities of structural organization of the masticatory muscles of rats in experimentally induced iodine deficiency. The research material involved masticatory muscle of 36 white outbred male rats, which were divided into groups: group І – intact animals; group ІІ – kept in iodine deficiency condition; group III – exposed to iodine deficiency with the addition of goitriferous food. All manipulations with test animals were performed in agreement with the regulations on the protection of vertebrate animals. The methods used in the study included: biochemical, histological, histochemical, submicroscopic, morphometric and statistical research methods. It has been established that under the conditions of iodine deficiency the lumen of arterial vessels in masticatory muscles becomes narrowed, the vascular vessels become thickened due to membrane oedema. The number of hemocapillaries per unit area of muscle fibre goes down in all the studied muscles. The number of muscle fibres with intermediate succinate dehydrogenase activity decreases with the simultaneous increase in muscle fibres with low succinate dehydrogenase activity. Furthermore, the oedematous changes are the most prominent in muscle fibres with low succinate dehydrogenase activity. In conditions of iodine deficiency with the addition of goitriferous products, we can observe the progression of luminal narrowing of the artery and wall thickening in masticatory muscles where oedematous-dystrophic changes are considerably marked. There is a tendency in the growth in haemocapillaries number per 1 μm2. Histostructurally, the loss of cross striation is quite noticeable. The cross-section diameter increases, especially in muscle fibres with low succinate dehydrogenase activity and muscle fibres with high succinate dehydrogenase activity in the masticatory muscle proper of immature animals. Ultrastructurally, the oedematous-dystrophic changes of myofibrils and mitochondria were revealed. Thus, under the conditions of iodine deficient diet the lumen of arterial vessels narrows in the masticatory muscles, their wall thickens due to oedema of the membranes, which progresses in iodine deficient diet with the addition of goitriferous products. The number of hemocapillaries per unit area of muscle fibre decreases in both study groups. Changes in vascular bed lead to the redistribution of the number of muscle fibres and their significant oedema.