RESUMO
The high level transection of the spinal cord (C-7) provokes a sustained increase of rat liver catecholamines: biphasic increase in norepinephrine level 1 hour and 24 hour after the operation and 7-fold increase of dopamine content 4 hour after the chordotomy. In contrast to cervical transection, sham operation causes only an initial catecholamine increase, the maximum being at the first hour after the surgery. Our experimental data indicate a possible participation of cervical spinal pathways in regulation of liver catecholamine content. It is also shown that bilateral adrenalectomy augments liver norepinephrine concentration in spinal rats as compared to the non-adrenalectomized ones. The results presented here indicate that cervical chordotomy affects the functioning of the sympatho-adrenal system, thus provoking specific changes in liver catecholamine content. The potential effect of such changes on a liver metabolic system (tyrosine aminotransferase induction) is discussed.
Assuntos
Catecolaminas/metabolismo , Fígado/metabolismo , Traumatismos da Medula Espinal/metabolismo , Adrenalectomia , Animais , Dopamina/metabolismo , Epinefrina/metabolismo , Cinética , Masculino , Norepinefrina/metabolismo , Ratos , Ratos Wistar , Tirosina Transaminase/metabolismoRESUMO
A dosed mechanical pressure of 12.5 kg/cm2 applied for 1 min on depilated mouse skin did not cause cellular death or visible alterations of the cellular ultrastructures. However, it had a strong effect on the mitotic cycle of the epidermal cells-stimulating the cells to enter the mitotic cycle and temporarily blocking the G1-->S transition. This effect was strictly limited to the pressed area of the skin. The proto-oncogene c-fos was induced within the first 2 min following application of the pressure. The level of c-fos mRNA showed two peaks during the next 24 h. The first slight peak was preceded by a rapid increase in the cAMP level in the pressed skin, the second-by a fall in the cAMP concentration. A model is suggested to explain the observed effects by reversible functional damage of the cellular membrane affecting the enzymes maintaining the steady state level of cAMP.
Assuntos
Células Epidérmicas , Genes fos , Mitose , Animais , AMP Cíclico/metabolismo , Epiderme/metabolismo , Epiderme/ultraestrutura , Regulação da Expressão Gênica , Masculino , Camundongos , Microscopia Eletrônica , Pressão , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
1. The effect of endotoxin on glucocorticoid (GC) induction of liver TO and TAT was investigated. 2. It was found that endotoxin inhibited not only TO GC induction, but also that of TAT, though to a lesser extent (17.41%). 3. Endotoxin did not influence the binding capacity of liver cytosol for 3H-dexamethasone at the second hour after the toxin administration. 4. In in vivo experiments endotoxin inhibited with 57.2% the binding of 3H-dexamethasone to hepatic nuclei. 5. It is suggested that the lower extent of endotoxin inhibition of GC induction of TAT may be due to the counteracting action of some inductor(s) for TAT only.
Assuntos
Dexametasona/metabolismo , Endotoxinas/farmacologia , Glucocorticoides/farmacologia , Fígado/enzimologia , Triptofano Oxigenase/antagonistas & inibidores , Tirosina Transaminase/antagonistas & inibidores , Adrenalectomia , Animais , Ligação Competitiva , Núcleo Celular/metabolismo , Citosol/metabolismo , Indução Enzimática/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Ratos , Ratos Endogâmicos , Triptofano Oxigenase/biossíntese , Tirosina Transaminase/biossínteseRESUMO
The effect of high level section of the spinal cord upon the hepatic cyclic AMP system was investigated in the rat. We report that transection of the spinal cord dramatically decreases the basal level of cyclic AMP from 0.88 nmol/g liver to 0.36 nmol/g at 1 h and to 0.20 nmol/g at 4 h. This was not due to increased activity of cyclic AMP phosphodiesterase or to decreased activity of basal adenylate cyclase. The sensitivity of adenylate cyclase to its usual effectors in vitro was not impaired. It is proposed that the lowering of liver cyclic AMP below its basal level after high level section of the spinal cord is due to decreased levels of hepatic catecholamines and/or plasma glucagon.
Assuntos
AMP Cíclico/metabolismo , Fígado/metabolismo , Medula Espinal/fisiologia , 3',5'-AMP Cíclico Fosfodiesterases/metabolismo , Adenilil Ciclases/metabolismo , Animais , Cordotomia , Glucagon/farmacologia , Fígado/efeitos dos fármacos , Masculino , RatosRESUMO
1. Reserpine given to rats before the enhanced synthesis of DNA begins 14h after partial hepatectomy markedly depresses thymidine uptake into DNA at 24 hours.2. At this time decreased activity of liver thymidine kinase but unchanged thymidine 5'-nucleotidase were observed.3. Reserpine has no effect on DNA synthesis when administered simultaneously with the labelled thymidine 2 h before killing.4. With depressed DNA synthesis after reserpine administration there is no significant decrease of liver RNA synthesis.
