Studies on the metabolism of nucleic acids and other constituents in the adrenal gland

Ramaiah, Turuvekere R (1959) Studies on the metabolism of nucleic acids and other constituents in the adrenal gland. PhD thesis, University of Glasgow.

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Abstract

1. The effect of administration of ACTH on the metabolism of nucleic acid, phosphelipid and protein in the adrenal gland has been studied in the guinea-pig and in the rat. 2. It has been shown that ACTH does not cause Changes in nucleic acid and protein content of the gland until several hours after administration. 3. ACTH causes hypertrophy as evidenced by an increase in RNAP content per cell, and hyperplasia as shown by an increase in DNAP content of the gland. The response in the guinea-pig is more rapid and more pronounced than in the rat. In the guinea-pig increases ranging from 85-110% over the control values are obtainable for RAP by stimulation with Acthar-gel for 3-5 days, or by stimulation with a combination of Acthar-gel and lyophilised ACTH for 24 hours. The increase in MAP amounts to about 30% over the control value. In the rat the maximal increase obtained in RNAP is about 30%, while no measurable increase occurs in DNAP. 4. The suppression of endogenous ACTH by administration of cortisol to the rat is shown to be as effective as hypophysectomy. Such treatment results in rapid and extensive damage to the cortex, as shown by the decrease in nucleic acid content. A similar suppression of endogenous ACTH in the guinea-pig by cortical administration does not cause a severe decline in the nucleic acid content of the gland. The suggestion is made, in order to explain these differences in the two species, that the adrenal in the rat is functioning under greater stimulation of endogenous ACTH, the lack of which causes rapid degeneration, while in the guinea-pig the stimulation by circulating ACTH is comparatively small. 5. Studios on 32P incorporation into RNA indicate that in the rat the increase in RNA content of the adrenal gland under ACTH stimulation is caused by the cessation of REA breakdown, while in the guinea-pig the stimulation causes increased rate of synthesis of RNA, so that AOTH appears to control RNA metabolism in different ways in the two species. 6. Incorporation of 32p into DNA has shown that synthesis of DNA in the adrenal gland of the normal animal is negligible, while ACTH stimulation causes a large increase in incorporation in the guinea-pig and a smaller increase in the rat. 7. The effect of severe ascorbic acid deficiency on adrenal nucleic acid metabolism has been studied in the guinea-pig. It has been shown that the hypertrophy of the gland which occurs in acute scurvy can be prevented by simultaneous administration of cortisol, so that the stress caused by the disease presumably results in enhanced pituitary secretion of ACTH. 8. Dietary changes have been shown to cause significant changes in the LP and the PrN content of the rat adrenal, without change in nucleic acid content and to alter the pattern of 32P incorporation into various fractions of adrenal tissue. A protein-free diet with a high energy intake causes a decrease in LP ones PrN, while an adequate protein diet also providing a high energy intake, causes an increase in LP and PrN. An energy-rich diet decreases the incorporation of 32P into the acid soluble fraction, this decrease being more pronounced when the diet is protein-free. 9. The presence of a tumour in the body produces pronounced changes in the adrenal of the rat, tending to increase the LP and PrN content of the gland without, however, any significant change in the nucleic acid content. There is a marked suppression of incorporation of 32P into the acid soluble fraction of the adrenal. Increased synthesis of DNA is indicated by an increase in the specific activity of the adrenal DNA of rate bearing an infected tumour. 10. The significance of these changes as well as the possible role RNA, DNA and LP in adreno-cortical function is discussed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: J N Davidson
Keywords: Pharmacology
Date of Award: 1959
Depositing User: Enlighten Team
Unique ID: glathesis:1959-72585
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06
URI: http://theses.gla.ac.uk/id/eprint/72585

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