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Biomedical subjects

A Guidotti

Publications and source records attributed to A Guidotti.

At least 235 records · Page 13Linked to original sources
PubMed1980

Modulation of nicotinic receptors by opiate receptor agonists in cultured adrenal chromaffin cells.

Morphological, physiological and pharmacological evidence indicates that opioid peptides, which in the brain are located intraneurally, may function as neurotransmitters. Similar evidence is not yet available for the opioid peptides that are stored in chromaffin cells of adrenal medulla and in axon terminals located in adrenal medulla and sympathetic ganglia. The present report contributes evidence suggesting that the opioid peptides which are stored in the axon terminals of the splanchnic nerves located in adrenal medulla may function as neuromodulators of the acetylcholine receptors located on chromaffin cells that are involved in catecholamine release. We support this functional role of the opioid peptides by showing that primary cultures of chromaffin cells of bovine medulla contain opiate receptors. When these receptors are occupied by specific agonists, the number of nicotinic receptors and the amount of catecholamine released by maximal doses of nicotine are reduced. Thus, like in other neuronal systems also in adrenal medulla, the action of opioid peptides is inhibitory. The specificity of this action is in part supported by the inability of opiate receptor agonists to reduce the Ca2+-dependent release of catecholamines elicited by K+ ions.

Adrenal Medulla↗
PubMed1980

Calmodulin in brain of schizophrenics.

A heat-stable Ca2+-dependent regular protein with the characteristics of calmodulin was extracted and purified from striatum and cerebral cortex of autopsied human brains. The human calmodulin preparation cross-reacts with Ca2+-dependent phosphodiesterase isolated from rat, bovine, and human cerebral cortex. There was no significant difference between calmodulin content measured in membranes obtained from striatum or cortex of nine control subjects without a psychiatric history and seven schizophrenic individuals.

Adult↗
PubMed1980

A simple and rapid method for the assay of cyclic GMP-dependent protein kinase.

A method for the isolation in partially purified cyclic GMP-dependent protein kinase (cGPK) from cerebellum is described. It involves a step-elution of an ion-exchange column charged with the post-mitochondrial supernatant of cerebellar homogenate. The cGPK activity is defined as the protein kinase activity in presence minus that in absence of cyclic GMP. Under the assay conditions used no interference by cyclic AMP-dependent protein kinase, and only negligible activities of cyclic nucleotide phosphodiesterase and phosphoprotein phosphatase could be detected.

Animals↗
PubMed1980

Prolonged survival of bovine adrenal chromaffin cells in rat cerebral ventricles.

Dispersed, cultured bovine adrenal chromaffin cells transplanted into the cerebral ventricles of neonatal and adult rats survived at least 2 mo without evidence of immunological rejection. The cells can be identified by their strong yellow fluorescent reaction with glyoxylic acid, which suggests that they maintain intact the capability of synthesizing and storing catecholamines. The cells did not show sprouting or process formation and appeared to be free in the ventricle or aggregated in clusters. This shows that cells from different animal species and from different tissue origins can be transplanted and can survive in the cerebral ventricles.

Adrenal Medulla↗
PubMed1979

GABA receptors in clonal cell lines: a model for study of benzodiazepine action at molecular level.

A "recptor unit" for gamma-aminobutyric acid (GABA), which includes brainlike receptor binding sites for tritium-labeled GABA and benzodiazepines (diazepam, clonazepam, and flunitrazepam) and a thermostable endogenous protein (GABA modulin) that inhibits both GABA and benzodiazepine binding, has been demonstrated in membranes prepared from NB2a neuroblastoma and C6 glioma clonal cell lines. In these cells, as in brain, diazepam (1 micromolar) prevents the effect of GABA modulin, and in turn GABA (0.oma and, to a lesser extent, the glioma cells represent a suitable model to study the interactions and the sequence of membrane and intracellular events triggered by the stimulation of benzodiazepine and GABA receptors.

Animals↗
PubMed1979

Action of harmaline and diazepam on the cerebellar content of cyclic GMP and on the activities of two endogenous inhibitors of protein kinase.

The rat cerebellum contains a significant amount of cGMP-dependent protein kinase, cAMP-dependent and cyclic nucleotide-independent protein kinase, and a large concentration of protein kinase inhibitors. These inhibitors are thermostable proteins which can be separated by gel chromatography into two molecular forms: the type 1 and type 2 inhibitors of protein kinase (14). The type 1 inhibitor blocks the rat cerebellar cAMP-dependent protein kinase activity while the type 2 inhibitor blocks the cGMP-dependent protein kinase, the cAMP-dependent protein kinase, and the cyclic nucleotide-independent protein kinases. The activity of the type 2 inhibitor increased or decreased in opposite direction to changes of cerebellar cGMP content generated by injection of 10 mg/kg harmaline 2.5 mg diazepam. No changes of type 1 inhibitor were observed under these conditions. The drug-induced shift of type 2 inhibitor of protein kinase was not mediated by changes in protein synthesis because it persisted after pretreatment with cycloheximide. These results are compatible with the hypothesis that cGMP modulates phosphorylation in cerebellum by changing the relationship between cGMP-dependent protein kinase and type 2 inhibitor content.

Alkaloids↗