Biomedical subjects

Jorge Pacheco-Rosado

Publications and source records attributed to Jorge Pacheco-Rosado.

3 recordsLinked to original sources

PubMed2005

Selective decrease of Na+/k+ -ATPase activity in the brain of hypothyroid rats.

The present work was performed in order to know if mild hypothyroidism in rats modifies the activity of the Na+/K+ -ATPase in different regions of the brain. Male Wistar rats (300-350 g) were randomly divided into three groups: (1) control group (n=8) drank tap water. (2) hypothyroid group (n=8) treated with 60 mg/kg of methimazole in drinking water; and (3) replaced group (n=8) treated with 60 mg/kg of methimazole plus 35 microg/kg of thyroid hormone (T3) in drinking water. After four weeks of treatment, the rats of all groups were sacrificed by decapitation. The cortex, amygdala, hippocampus and cerebellum were dissected and frozen at -70 degrees C until assay. For enzymatic assay, the tissues were homogenized. The Na+/K+ -ATPase activity was determined by quantifying inorganic phosphate after the samples were incubated with ATP in the presence and absence of 1 mM ouabain. The Na+/K+ -ATPase activity is expressed as pmoles Pi/hr/mg protein. The results showed that the Na+/K+ -ATPase activity in the cortex, amygdala and hippocampus, but not in cerebellum, was lower in hypothyroid group than in control group (p<0.05). The co-administration of methimazole and T3 avoided the decrease of Na+/K+ -ATPase activity, except in amygdala. According to the results obtained we concluded that methimazole treatment decreased the Na+/K+- ATPase activity in the brain's regions which are related to seizures onset. That decrement in enzyme activity was avoided with the coadministration of thyroid hormone.

Animals↗

PubMed2004

Perinatal hypothyroidism increases the susceptibility to lidocaine-kindling in adult rats.

The present study was developed to ascertain whether or not susceptibility to lidocaine-kindling persists into adulthood in perinatal hypothyroid rats. Pregnant Wistar rats were randomly divided into two groups: the first one, a control group, that drank tap water; and a second one, a hypothyroid group, were treated with 0.02% propylthiouracil in their drinking water from the 14th gestational day to the 10th postpartum day. The pups of both groups were maintained with food and tap water ad libitum until the experiment was over. The pups of each group were divided to test the susceptibility to lidocaine-kindling at 30 and 100 days old, for this, lidocaine (50 mg/kg, i.p.) was administered daily. The seizures were usually present in the form of tonic attacks of fore and hind limbs, followed by intermittent clonic movements. An animal was considered kindled when it showed clonic movements for two consecutive days. We observed that the number of stimuli necessary to produce lidocaine-kindling seizures in hypothyroid rats was significantly lower than in the control group for both ages. Also, the percentage of kindled rats aged 30 days (73% and 89%) was greater than aged of 100 days (26% and 59%) in both control and hypothyroid groups, respectively. In conclusion, the perinatal hypothyroidism increases the susceptibility to lidocaine-kindling in adult rats.

Age Factors↗

PubMed2004

Kainic acid does not affect CA3 hippocampal region pyramidal cells in hypothyroid rats.

Thyroid hormones exert a crucial role on trophic events of the central nervous system during development, adulthood, and ageing. The deficiency of thyroid hormones could also produce a deficiency in neurotransmission in the hippocampal region. Kainic acid (KA) has become an important tool for studying functions related to excitatory amino acid transmission in mammals. Its neurotoxic effects on the pyramidal neurons of the CA3 hippocampal region are well known. We have examined the neurotoxicity of KA on these cells in hypothyroid rats. The hypothyroid state was induced by administration of methimazole. After 4 weeks of treatment, KA was administered once intraperitoneally at doses of 0, 1, 2.5, and 5mg/kg to the hypothyroid group, and 0 and 5mg/kg to the euthyroid group. In the euthyroid group, KA reduced the neuronal density in the CA3 hippocampal region, and in the hypothyroid rats with no administration of KA, the neuronal density of the CA3 hippocampal region is reduced also. Administering KA in hypothyroid rats did not reduce the number of CA3 pyramidal cells.

Animals↗