In almost all cases of adult onset "diseases," excess biochemical
activity (usually in the form of AA metabolites) causes dysfunction.
The evidence is so overwhelming that it's actually funny. Do some
www.pubmed.com searches.
Here are a couple of recent ones:
Cell Biochem Funct. 2003 Dec;21(4):325-30.
Oxidative damage and antioxidant enzyme activities in experimental
hypothyroidism.
Yilmaz S, Ozan S, Benzer F, Canatan H.
Department of Biochemistry, College of Veterinary Medicine, Firat
(Euphrates) University, Elazig 23119, Turkey. [email hidden]
Free radicals are now well known to damage cellular components. To
investigate whether age and thyroid level affect peroxidation speed, we
examined the levels of malondialdehyde and antioxidant enzyme
activities in different age groups of hypothyroid rats. Hypothyroidism
was induced in 30- and 60-day-old Wistar Albino rats by the i.p.
administration of propylthiouracil (10 mg kg(-1) body weight) for 15
days. While malondialdehyde levels of 30- or 60-day-old hypothyroid
rats were increased in liver, they were decreased in the tissues of the
heart and thyroid. While glucose-6-phosphate dehydrogenase activity
levels did not change in heart, brain and liver tissues of 30-day-old
rats, they increased in brain and heart tissues of 60-day-old
experimental groups, but decreased in the liver. Catalase activities
decreased in the liver and heart of rats with hypothyroidism, but
increased in erythrocytes. In control groups while malondialdehyde
levels increased in brain, heart and thymus with regard to age, they
decreased in plasma. Glucose-6-phosphate dehydrogenase and catalase
activities were not affected by age in tissues of the thymus, thyroid
and brain, but they were decreased in the heart tissue. The changes in
the levels of lipid peroxidation and antioxidant enzyme activities
which were determined in different tissues of hypothyroid rats indicate
a cause for functional disorder of these tissues. Moreover, there may
be changes depending on age at lipid peroxidation and antioxidant
enzyme activity levels. Copyright 2003 John Wiley & Sons, Ltd.
Indian J Exp Biol. 2003 Nov;41(11):1334-7.
Changes in lipid peroxidation and free radical scavengers in kidney of
hypothyroid and hyperthyroid rats.
Sawant BU, Nadkarni GD, Thakare UR, Joseph LJ, Rajan MG.
Laboratory Nuclear Medicine Section, Isotope Group, (BARC), C/o Tata
Memorial Centre Annexe, Parel, Mumbai 400 012, India.
[email hidden]
Kidney weight was significantly decreased in hypothyroidism (induced by
Na131I administration) and increased in hyperthyroidism (induced by
thyroxine treatment) as compared to control in female Wistar rats. The
tissue lipid peroxidation level remained unchanged in hyperthyroid rats
but significantly increased in hypothyroid rats. Superoxide dismutase
was decreased in both experimental groups but more so in hyperthyroid
rats. Catalase was reduced significantly in hyperthyroid rats but
remained unaffected in hypothyroid rats. Tissue glutathione peroxidase
(GPx) activity was increased while reduced glutathione levels remained
unaltered in both hypothyroid and hyperthyroid rats. Plasma GPx
activity was significantly low in both the hypothyroid and hyperthyroid
rats. The results suggest alterations in the oxidative stress in
hypothyroid and hyperthyroid rat kidneys with concomitant changes of
free radical scavengers.