Drugs online research references
Neurochem Int. 1993 Jun;22(6):589-98.
Developmental changes in rat brain monoamine metabolism and beta-adrenoceptor subtypes after chronic prenatal exposure to propranolol.
Erdtsieck-Ernste EB, Feenstra MG, Botterblom MH, Boer GJ.
Netherlands Institute for Brain Research, Amsterdam.
The aim of this study was to investigate whether a chronic prenatal beta-blockade can alter the maturation of the noradrenergic system in the rat brain. Pregnant female and adult male rats were treated for 10 days with the beta-antagonist propranolol dissolved in the drinking water (40-50 mg/kg/day). Direct and long-term effects on beta-adrenoceptors and monoamine metabolism in various rat brain regions were determined. After the prenatal treatment the propranolol level in the foetal brain was 0.9 micrograms/g, while in the adult brain 2.0 micrograms/g was present. The foetal beta 1-receptors were significantly up-regulated by propranolol (200%), whereas the beta 2-receptor number remained unaltered. On postnatal days 4 and 21 the number of both beta-subtypes was the same as that of controls. Noradrenaline, its metabolite 3-methoxy-4-hydroxyphenylglycol and their ratio were unaltered directly after the prenatal treatment. In the PN 21 offspring, however, the metabolite level had increased in the frontal cortex (+ 17%) and hippocampus (+ 32%), and the ratio in the hippocampus (37%) and medulla pons (+ 34%). Prenatal treatment also induced a significant increase of the 5-hydroxyindoleacetic acid.5-hydroxytryptamine ratio (+ 15%) in the medulla pons at GD 21. No direct or lasting effects were found on dopamine metabolism. Propranolol treatment of adult rats gave no direct changes in monoamine metabolism. We concluded that chronic prenatal propranolol exposure (a) reversibly up-regulates foetal beta 1-adrenoceptors, and (b) increases the NA activity in the brain in later life.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8390323&dopt=Abstract
J Neurochem. 1993 Jul;61(1):80-4.
Mechanisms of alpha-Sialosyl cholesterol action to suppress both cyclic AMP production and DNA synthesis of rat glial cells.
Ito J, Kato T, Tanaka R.
Department of Biochemistry, Nagoya City University Medical School, Japan.
alpha-Sialosyl cholesterol (alpha-SC) that elicited morphological differentiation of rat astrocytes not only lowered intracellular cyclic AMP (cAMP) levels but also inhibited cAMP production induced by either alpha-isoproterenol, cholera toxin, or forskolin. The targets of alpha-SC in the cAMP production system of rat astrocytes were investigated to understand the mechanism of the alpha-SC action on cAMP production. cAMP production evoked by alpha-isoproterenol (1 microM) was entirely canceled by beta blockers such as propranolol and timolol (1 microM), but not by alpha-SC. Concentrations of alpha-SC greater than 15 microM were required for 50% inhibition of the activation by a beta agonist. Although alpha-SC inhibited in a dose-dependent manner the activities of membrane-associated adenylate cyclase that had been stimulated by either GTP gamma S of forskolin, alpha-SC inhibited neither GTP-binding activities nor GTPase activities of the membrane-associated G proteins. These findings suggest that alpha-SC suppresses adenylate cyclase directly, but not beta receptors or G proteins, and that it promotes the morphological differentiation of rat astrocytes through a mechanism regulating directly the cytoskeletal organization, regardless of intracellular cAMP level. alpha-SC (30 microM) suppressed 40% of DNA synthesis in the cell-free system, which contained the cytosolic extracts and the nucleus fraction prepared from rat astrocytoma C6 cells. Approximately 25% of alpha-SC incorporated in the astrocyte cytoplasm was transferred to the nuclei by 10 min after the addition.(ABSTRACT TRUNCATED AT 250 WORDS)
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8390569&dopt=Abstract
Eye. 1993;7 ( Pt 1):122-6.
Beta-adrenergic receptors in human anterior optic nerve: an autoradiographic study.
Dawidek GM, Robinson MI.
Department of Ophthalmology, University Hospital of Wales, Cardiff.
Sections of human anterior optic nerve and nerve head were incubated in a physiological solution containing a radiolabelled beta blocker at a low concentration. The beta blocker used was (-)-(125iodo)-cyanopindolol, which has a high affinity and specificity for beta-adrenergic receptors. Concurrent incubations were performed with a great excess of unlabelled beta blocker added to demonstrate non-specific binding. Following incubation the sections were washed and dried. They were then apposed to photographic film for 5 days and developed. Incubations were performed with the stereoisomers of propranolol and an alpha blocker as well as specific beta-one and beta-two blockers. Beta-adrenergic receptors were demonstrated in anterior optic nerve and optic nerve head. The majority were of the beta-two subtype.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8392006&dopt=Abstract
Herbs and Pharmaceuticals Online ||
Hair Million herbal formula for hair loss and hair growth ||
Wellstreet online pharmacy for click-order prescription medications ||
Altace Online Pharmacy ||
Rx Drugs USA, Prescription Drugs Online Pharmacy ||
Insurance plans and information ||
Insurance policies for all purposes ||
Antibiotics and prescription medications online literature ||