Experimental Hypothyroidism Inhibits δ-Aminolevulinate Dehydratase Activity in Neonatal Rat Blood and Liver

Propylthiouracil-induced hypothyroidism during lactation alters leucine and mannose metabolism in rat cerebellar slices

Thyroid hormone deficiency during perinatal development results in significant alterations in neurological functions. The relationship between such events and brain metabolism is not completely understood. The aim of this study was to investigate the effects of hypothyroidism on leucine, mannose, glucose and lactate metabolism in rat cerebellar slices. Experimental hypothyroidism was induced by exposing mothers and pups to propylthiouracil (PTU) until weaning - postnatal day 21. Metabolic analyses were performed in postnatal day 10 (PND10) and 21 (PND21) animals. A matching group of animals received the same oral treatment also after weaning until adulthood PND60 with T3 supplement during lactation (P1-P21). In PND21 animals, PTU treatment significantly increased the rate of leucine oxidation to CO2, although glucose and lactate oxidations were not affected. PTU treatment also increased the oxidation of leucine to CO2 at PND60 (adult animals). PND10 hypothyroidism animals showed a decrease in conversion of mannose to glycolipids and glycoprotein compared with the control group. However, PTU treatment increased the conversion of mannose to glycolipids and glycoprotein in PND21 animals. The replacement of T3 normalized mannose and leucine metabolism in adult rats. These results indicate that deficits in thyroid hormones during lactation could delay or alter brain development and metabolism.

Cardiovascular and hematologic effects produced by chronic treatment with etoricoxib in normotensive rats

PURPOSE

Evaluate the cardiovascular and hematological effects produced by chronic treatment with two dosis of etoricoxib in Wistar normotensive rats.

METHODS

Thirty rats have been used and divided into one control group and two etoricoxib (10mg/kg and 30mg/kg) treatments groups for 60 days. The mean arterial pressure (MAP) was taken during the whole experimental period and at the end of this period, under anesthesia blood samples were taken, and further the withdrawn of the aorta, heart, brain, liver, and kidneys for the anatomopathologic study.

RESULTS

The treatment with etoricoxib (30mg/Kg) produced a significant increase of the MAP from the 28th day of the experiment and from the platelets when compared to the control group and to the group treated with 10mg/Kg, besides producing a highly significant difference in hematocrit and in the red blood cells in relation to the control group. On the other hand the treatment with etoricoxib has not caused histopathological changes when compared to the control.

CONCLUSION

These data show that the chronic treatment with etoricoxib leads to increase of the MAP, and to important hematological changes which seem to be associated to the hemoconcentration although not producing anatomopathological significant changes.

Congenital hypothyroidism is associated with intermediate filament misregulation, glutamate transporters down-regulation and MAPK activation in developing rat brain

Developmental thyroid hormone (TH) deficiency leads to mental retardation and neurological deficits in humans. In this study, congenital hypothyroidism was induced in rats by adding 0.05% 6-propyl-2-thiouracil in the drinking water during gestation and suckling period. This treatment induced hyperphosphorylation of neurofilaments, the neuronal intermediate filament (IF) proteins, of heavy, medium and low molecular weight (NF-H, NF-M and NF-L, respectively) without altering the phosphorylation level of astrocyte IF proteins, glial fibrillary acidic protein (GFAP) and vimentin in cerebral cortex of rats. NF-H was hyperphosphorylated on KSP repeats in the carboxy-terminal tail domain. Furthermore, the immunocontent of GFAP and NF subunits was down-regulated, while vimentin was unaltered both in tissue homogenate and in cytoskeletal fraction of hypothyroid animals. Moreover, we verified the immunocontent of astrocyte glutamate/aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) as well as activation of mitogen-activated protein kinases (MAPKs) in hypothyroid rats. Results showed that hypothyroidism is associated with decreased GLAST and GLT-1 immunocontent. Additionally, we demonstrated increased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation without altering Jun N-terminal kinase (JNK) and p38(MAPK) phosphorylation. However, total JNK levels were down-regulated. Taken together, these results suggest that the thyroid status could modulate the integrity of neuronal cytoskeleton acting on the endogenous NF-associated phosphorylating system and that such effect could be related to glutamate-induced excitotoxicity, as well as ERK1/2 and JNK modulation. These events could be somehow related to the neurological dysfunction described in hypothyroidism.