The influence of thyroxine on intensity of energy metabolism in bone marrow myeloid cells and neutrophilic polymorphonuclear leukocytes of neonatal pig.
OBJECTIVE
To investigate the participation of thyroxine in the regulation of energy metabolism in neutrophilic polymorphonuclear leukocytes and their bone marrow precursors.


METHODS
The influence of L-thyroxine (T4; 4 mg/kg every 12 hr from day 2 to 10 of age) was estimated on the activity of hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G-6-PDH), NADP-dependent isocitrate dehydrogenase (ICDH) and cytochrome C-oxidase in bone marrow myeloid cells and circulating neutrophils of 3, 5 and 10 day (d) old piglets. Serum T4 and 3,5, 3'-triiodothyronine (T3) concentrations were estimated at every stage of experiment by radioimmunoassay. Bone marrow cells of myeloid lineage and blood neutrophilic polymorphonuclear leukocytes were separated by differential centrifugation of haematopoietic cell suspension using Ficoll-Hypaque gradients.


RESULTS
The hyperthyroid status resulted in significant increase in PFK and LDH activity in myelokaryocytes of 3 and 3-5 d piglets, while the activity of HK and PK in the cells of 3-10 d animals remained unchanged. Moreover, ICDH activity in myelokaryocytes increased on day 10 and that of cytochrome C oxidase in bone marrow cells at all intervals. Marked increase in HK and LDH activity on day 3-5 was found also in blood polymorphonuclear granulocytes, while PFK and PK activity was increased during the whole period. At the same time even the increase in ICDH and cytochrome C-oxidase activity was observed, respectively, in 3 and 5-10 d old piglet neutrophils. Besides that, T4 inhibited G-6-PDH activity in myeloid cells on day 3 to 10 and did not influence the enzyme activity in circulating leukocytes.


CONCLUSIONS
The administration of T4 resulted in preferential stimulation of oxidative stages of carbohydrate catabolism in myelocaryocytes, while the activity of glycolytic enzymes in these cells was less affected. On the contrary, the enzymes of glycolysis in blood neutrophils showed higher sensitivity to T4 action as compared to catalysts of oxidative reactions. The intensity of pentose phosphate pathway seems to be inhibited in bone marrow myelocaryocytes of T4 treated animals, while that in blood leukocytes remained unaffected.
Lviv State Medical University, Department of Biochemistry, Ukraine, babych@prima.meduniv.lviv.ua
H
H
Babych
H
H
Antonyak
A Y
AY
Sklyarov
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006098:Granulocytes / Q000201:enzymology / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009249:NADP / Q000494:pharmacology; D009504:Neutrophils / Q000201:enzymology / Q000378:metabolism*; D010732:Phosphofructokinase-1 / Q000378:metabolism; D013552:Swine; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology*; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D009249:NADP; D007770:L-Lactate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D003576:Electron Transport Complex IV; D006593:Hexokinase; D010732:Phosphofructokinase-1; D013974:Thyroxine