Effects of thyroid and adrenal cortical hormones on restoration of liver protein and enzyme activity after partial hepatectomy in rats

Abstract

Propylthiouracil depressed and thyroxine elevated the succinoxidase activity of rat liver after 4 days of regeneration. Protein-depleted animals had a significant decrease in activity of succinic dehydrogenase and cytochrome oxidase, rate of restoration of liver mass, enzyme activity and new protein. Thyroxine increased the rate of regeneration and the enzyme activity even in protein-depleted animals. Adrenalectomized rats on low protein intake had a very low rate of regeneration and protein replacement and low amounts of new enzyme activity and new protein after partial hepatectomy. Increasing the dietary protein to 36% increased all of these factors significantly, but administration of cortisone or adrenal cortical extract, had little effect on enzyme activity even though its effect on protein restoration was about as good as that of the high protein intake. Apparently under certain conditions, these hormones can produce changes in specific enzyme proteins that are independent of changes in total cell protein.

Histochemical Studies of Regenerating Rat Liver in Experimental Cirrhosis after Partial Hepatectomy

“…Any other con clusion would be entirely speculative for the time being. Anyhow, il is worth while to mention the interesting observation of Tipton et al (1959) according to which the activity of succinic dehydro genase is increased by thyroxin but depressed by propylthiouracil on the fourth day of regeneration. One of the important functions of the liver being inactivation of Ihe hormones of the thyroid gland as well that of the corticosteroids (cf.…”

Amphibian regeneration and cellular heterochrony

“…This hypothesis would explain both regeneration (retrodifferentiation ~ redifferentiation) and malignancy (retrodifferentiation) and possibly even the reversal of malignancy (retro-differentiation ~ redifferentiation). The observations made by Adle et al (1958) and Tipton et al (1959), that the thyroid hormones thyroxine (T4) and triiodothyronine (T3) enhance rat liver regeneration, provide indirect evidence to support the hypothesis.…”

Effect of adrenal cortical steroids on liver regeneration

“…With rats bilaterally adrenalectornized and partially hepatectomized simultaneously, liver regeneration was reported to be depressed (Berman et al, 1947;Friedgood et al, 1950;Ferrari and Harkness, 1954;Tipton et al, 1959). When partial hepatectomy was carried out 2-10 days after adrenalectomy, a depression was noted by Rapport et al (1948) and Mehrotra and Mangalik (1956), an increase by Drabkin (1 950), and essentially no effect according to others (Canzanelli et al, 1949;Seidman et al, 1966;Stevens and Dougherty, 1968).…”

“…In this regard, the findings with steroids in such rats are in conflict. Thus, adrenal cortical extract was found to substitute for adrenalectomy, but deoxycorticosterone acetate (DOCA) appeared t o be stimulatory (Berman et al, 1947;Friedgood et al, 1950) and cortisone and adrenal cortical extract caused an increase in new protein (Tipton et al, 1959;Roberts, 1953); regeneration was said t o be depressed by cortisone (Stevens and Dougherty, 1968;Mehrotra and Mangalik, 1956) and by deoxycorticosterone acetate according to the last two workers. The doubly operated animals as such or in relation to the steroids have also been explored with respect to mitosis-stimulating principles (Cardoso et al, 1967), hepatic and serum lipids (Cardoso et al, 1968;Simek et al, 1968;Husakova and Simek, 1970) and to the distribution of electron-opaque bodies in the hepatic cells (Trotter, 1967).…”