Effect of hypothyreosis on the content of ceramides in rat tissues.
Ceramide is the second messenger in the sphingomyelin signalling pathway. A number of extracellular stimuli increase the content of ceramide in the cell. There are some data indicating that the content of ceramide may also be regulated by hormones. The aim of the present study was to examine the effect of hypothyreosis on the content and composition of ceramide in rat tissues. The rats were thyroidectomized and thereafter they received propylthiouracyl in drinking water. The control rats were sham operated. 30 days after thyroidectomy or sham operation the rats were anaesthetized and samples of the liver, white and red vastus lateralis and left ventricle were taken. One set of samples was frozen in liquid nitrogen for analysis of ceramide. Another set of samples was freshly homogenized in chloroform/methanol for further determination of the content of sphingomyelin phosphorous. The content and composition of ceramide-fatty acids was determined by means of gas-liquid chromatography. Twelve ceramides containing different fatty acid residues were identified in both groups. Hypothyreosis reduced the total content of ceramide in each tissue studied: in the heart by 50.9%, in the red vastus by 28.6%, in the white vastus by 29.4% and in the liver by 22%. Concomitantly, the content of individual ceramides was either reduced, stable or even elevated, depending on the tissue. The content of sphingomyelin was elevated in both sections of the vastus lateralis and remained stable in the heart and the liver. The ratio: total content of sphingomyelin to total content of ceramide was elevated in the muscles and remained stable in the liver. This indicates that the reduction in the content of ceramide in the tissues of hypothyroid rats may be a consequence either of a reduction in the formation of ceramide from sphingomyelin, its increased hydrolysis or both. It is concluded that normal thyroid function is needed to maintain the content and composition of ceramide in the tissues.
Górska
M
M
Department of Gerontology, Medical University of Białystok, Białystok, Poland. gorski@amb.edu.pl
Dobrzyń
A
A
Langfort
J
J
Górski
J
J
D000818:Animals; D002518:Ceramides / Q000378:metabolism*; D002849:Chromatography, Gas; D007037:Hypothyroidism / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013109:Sphingomyelins / Q000378:metabolism; D013961:Thyroid Gland / Q000502:physiology; D013965:Thyroidectomy; D014018:Tissue Distribution
D002518:Ceramides; D013109:Sphingomyelins