Biomaterial Database

Thyroxine effect upon activity of uridine kinase in developing rat cerebellum. 1977

M E Weichsel

Experimental hyperthyroidism in the neonatal rat is known to accelerate cerebellar DNA biosynthesis resulting ultimately in a deficit in cell number at maturity. Because of the know shift to an earlier age in the developmental curve for cerebellar thymidine kinase activity in rats treated with thyroxine, we studied the activity of uridine kinase and DNA biosynthesis during rat cerebellar development under hyperthyroid conditions. Body weight and cerebellar wet weight in treated animals were noted to be significantly decreased below control values on days 4 and 12, respectively. Cerebellar DNA was significantly elevated above control values on days 4 and 6 (132 and 129% of control, respectively). Subsequently, DNA content fell significantly below control values through day 18. Uridine kinase activity was found to be increased significantly above control values at ages 2, 4, and 6 days (maximum 119% of control at age 4 days) following which activity fell significantly below control values by 15 days of age. Uridine kinase activity from both treated and control animals fell only moderately after the time of peak activity between 9 and 15 days of age, although the peak of the developmental curve for the enzyme appeared earlier in the treated animals. The data show a less pronounced early stimulation of cerebellar uridine kinase by thyroxine compared with previously reported thyroxine enhancement of thymidine kinase activity, although both enzymes are affected by thyroxine throughout cerebellar ontogenesis. The study thus provides evidence that uridine kinase is sensitive to hormonal stimulation during early stages of active cerebellar cell division, and that the enzyme may relate most closely in brain to the synthesis of RNA as well as the sustaining of cell function after the most active phase of cellular proliferation. In addition, the study emphasizes the use of enzyme-hormone relationships during development to provide information concerning critical interrelationships between metabolic pathways contributing to nucleic acid biosynthesis.

UI	MeSH Term	Description	Entries
D006980	Hyperthyroidism	Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE.	Hyperthyroid,Primary Hyperthyroidism,Hyperthyroidism, Primary,Hyperthyroids
D009929	Organ Size	The measurement of an organ in volume, mass, or heaviness.	Organ Volume,Organ Weight,Size, Organ,Weight, Organ
D010770	Phosphotransferases	A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7.	Kinases,Phosphotransferase,Phosphotransferases, ATP,Transphosphorylase,Transphosphorylases,Kinase,ATP Phosphotransferases
D001835	Body Weight	The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.	Body Weights,Weight, Body,Weights, Body
D002531	Cerebellum	The part of brain that lies behind the BRAIN STEM in the posterior base of skull (CRANIAL FOSSA, POSTERIOR). It is also known as the "little brain" with convolutions similar to those of CEREBRAL CORTEX, inner white matter, and deep cerebellar nuclei. Its function is to coordinate voluntary movements, maintain balance, and learn motor skills.	Cerebella,Corpus Cerebelli,Parencephalon,Cerebellums,Parencephalons
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D000367	Age Factors	Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.	Age Reporting,Age Factor,Factor, Age,Factors, Age
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000831	Animals, Newborn	Refers to animals in the period of time just after birth.	Animals, Neonatal,Animal, Neonatal,Animal, Newborn,Neonatal Animal,Neonatal Animals,Newborn Animal,Newborn Animals
D012313	RNA	A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated