A comparison of the effect of L-triiodothyronine on the plasma lipid and cholesterol concentrations of the rat, chicken and guinea pig

Effect of thyroxine and thiourea on cholesterol total lipid and glycogen contents of brain of Singi fish (Heteropneustes fossilis bloch)

Three consecutive days injections of thyroxine of different doses (1, 2 and 4 ?g/g of body weight) caused significant increase in cholesterol content of cerebrum of Singi fish at 25 degrees C in comparison to the control. The cholesterol content of cerebellum, midbrain and medulla oblongata was enhanced significantly with higher doses of 2 and 4 ?g of thyroxine per g of body weight. The lipid and glycogen contents of whole brain were also found to increase with different doses of thyroxine after three consecutive days injections. These cellular constituents decreased with hypothyroid condition induced by thiourea treatment. The results indicate the thyroid hormonal regulation of lipid and carbohydrate metabolism in brain of Singi fish.

Intermediary metabolism in a lizard, Calotes versicolor: role of thyroid hormones

In Calotes versicolor, thyroidectomy did not alter the blood glucose level, lactate dehydrogenase (LDH liver and heart), acid phosphatase (Ac.Pase liver and kidney), and alkaline phosphatase (Alk.Pase liver and kidney) activities; significantly decreased the activities of glucose-6-phosphatase (G-6-Pase liver and kidney), glutamic oxaloacetic transaminase (GOT liver and heart), glutamic pyruvic transaminase (GPT liver), and urea concentration (liver and kidney); and increased liver cholesterol when compared to sham-operated controls. Administration of L-thyroxine (L-T4) or triiodo-L-thyronine (L-T3) to thyroidectomized lizards significantly stimulated the activities of G-6-Pase, Ac.Pase, GOT and GPT, concentration of glucose and urea, and decreased the cholesterol level. While the activities of all the enzymes studied and cholesterol level remain unchanged, glucose and urea levels decreased and increased, respectively, in thyroidectomized animals treated with actinomycin D. Chloramphenicol treatment did not affect any of the parameters studied. Simultaneous injections of actinomycin D or chloramphenicol with L-T4 prevented the hormone-stimulated activities of Ac.Pase, GOT, and GPT while the activities of LDH, G-6-Pase, Alk.Pase, glucose, urea, and cholesterol levels remain unchanged.