Effects of hypo- and hyper-thyroidism on in vivo lipogenesis in fed and fasted rats.
Thyroidectomized rats (T) daily injected with either 0, 0.1, 1.8 or 25 microgram of L-thyroxine/100 g body wt. were compared with intact controls (C). The appearance of radioactivity in fatty acids 30 min after the i.p. injection of (3-14C)pyruvate was reduced in adipose tissue and enhanced in liver of T+25, being no differences between the other groups and C. (14C)-Fatty acids are reduced with 3 h of fasting only in the adipose tissue of T+1.8 and C, while 24 h produces a reduction in liver in the T+1.8, T+25 and C, and in adipose tissue in the T+1.8 and C animals. The highest percentage of radioactivity was observed in the liver glyceride glycerol fraction, being greater in T+25 than in the other groups. Fasting produces an increment in the (14C)-glyceride glycerol fraction. Being significant only in thehypothyroid animals in both liver and adipose tissue. The most sensitive parameter to fasting was the formation of (14C)-non-saponifiable lipid in both the C and T+1.8 animals, while it does not change in T+0 or T+0.1, but is enhanced within 24 h in the adipose tissue of T+25. It is proposed that most of the observed changes are due to the other endocrine disfunction s which appear in hypo- and hyperthyroidism, as the in vivo results do not comply with in vitro effects of thyroxine onlipogenesis of others.
D000818:Animals; D001835:Body Weight; D004822:Epididymis / Q000378:metabolism; D005215:Fasting; D005227:Fatty Acids / Q000096:biosynthesis; D005989:Glycerides / Q000096:biosynthesis; D006980:Hyperthyroidism / Q000378:metabolism*; D007037:Hypothyroidism / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism; D008297:Male; D011773:Pyruvates / Q000378:metabolism; D051381:Rats; D013965:Thyroidectomy; D013974:Thyroxine
D005227:Fatty Acids; D005989:Glycerides; D008055:Lipids; D011773:Pyruvates; D013974:Thyroxine