Biomedical subjects

F Amenta

Publications and source records attributed to F Amenta.

333 records · Page 19Linked to original sources

PubMedDate not supplied

Dopamine receptors in the rat thymus.

Radioreceptor assay and autoradiographic techniques with 3H-SCH 23390 as a ligand were used to characterize pharmacologically and to localize anatomically dopamine D-1 receptor sites in sections of rat thymus. 3H-SCH 23390 was specifically bound to sections of rat thymus in a manner consistent with the labeling of D-1 receptor sites. Autoradiography demonstrated the accumulation of 3H-SCH 23390 binding sites in the cortex of the thymus rather than in corpuscles.

Animals↗

PubMedDate not supplied

Similarity of age-dependent changes in renal and striatal dopamine receptors.

A comparative analysis of the age-dependent changes in renal DA-1 and striatal D-1 dopamine receptors was performed in 3-(young), 12-(adult) and 27-(aged) month-old male Wistar rats by means of combined radioreceptor binding and autoradiographic techniques. 3H-SCH 23390 was used as a ligand of DA-1 or D-1 receptors. Experiments were performed on frozen sections of the kidney and of the striatum. The affinity of the ligand for both renal or striatal receptors did not show age-dependent changes. A significant loss in the density of DA-1 and D-1 sites was observed in the adult in comparison with young rats. A further decrease in the density of these sites was noticeable between adult and aged animals. These results suggest that renal DA-1 and striatal D-1 receptors are sensitive to aging to the same extent.

Aging↗

PubMedDate not supplied

Autoradiographic localization of peripheral [3H]-hydergine binding sites.

The anatomical distribution of the ergot derivative [3H]-hydergine (co-dergocrine mesylate) was analyzed by the use of an in vitro autoradiographic technique on frozen sections of rat heart, mesenteric and renal arteries, adrenal gland and kidney. In the heart, [3H]-hydergine was bound by atria and by myocytes of ventricles. In the arterial wall, the drug was bound primarily by the adventitia, by the adventitia-media border and by the intimal layer. The density of adventitial and adventitial-medial binding sites has an inverse relation with the diameter of mesenteric or renal vessels. In the adrenal gland, [3H]-hydergine was bound primarily by the medulla and, in lesser amounts, by the zona glomerulosa. In the kidney, the drug was localized within the arterial tree as well as in cortical tubules and in medullary collecting tubules. The above findings suggest that [3H]-hydergine is bound by various structures involved in the regulation of cardiovascular homeostasis. Interaction with these sites probably accounts for the antihypertensive action of hydergine.

Adrenal Glands↗

PubMedDate not supplied

Are muscarinic receptors present in rat pial or intracerebral vessels?

Experiments were performed to determine whether muscarinic receptors were present within rat pial or intracerebral vessels. Localization of muscarinic receptors was determined by autoradiography using [3H]-quinuclidinyl benzilate ([3H]-QNB) as a ligand on brain sections of the frontoparietal and the temporal cortex, the neostriatum and the hippocampus. [3H]-QNB was bound specifically to sections of rat brain in a manner consistent with the labelling of muscarinic receptors. A high density of muscarinic receptors was found primarily in the neostriatum, followed, in descending order, by the cerebral cortex and the hippocampus. However, no specific [3H]-QNB binding was observed at the level of either the pial or intraparenchymal vessels. On the basis of the present data, the existence of muscarinic receptors within rat pial arteries and arterioles, as well as within intracerebral vessels, seems to be highly questionable.

Animals↗

PubMedDate not supplied

Muscarinic cholinergic receptors in the hippocampus of the aged rat: effects of long-term hydergine administration.

The effects of senescence and of long-term hydergine treatment on the density and the pattern of muscarinic cholinergic receptors in rat hippocampus were studied using combined radioreceptor binding and autoradiography with [3H]-quinuclidinyl-benzilate ([3H]-QNB) as a ligand. [3H]-QNB accumulated in the hippocampus of 3 month old rats, primarily in the stratum oriens of the CA1 and CA2 fields, followed in descending order by the molecular layer of granule cells of the dentate gyrus and the CA3 field. The density and pattern of [3H]-QNB binding sites in the hippocampus of 16 month old rats were the same. In contrast, the density of [3H]-QNB binding sites in the hippocampus of 22 months old rats was significantly reduced, mainly in the granule cells of the dentate gyrus, next in the CA3 and in the CA1-CA2 fields. Hydergine treatment (0.6 mg/kg and 1 mg/kg, p.o.), started at 16 months of age and continued for 6 months, caused a dose-related restoration of the number of [3H]-QNB binding sites, primarily in the CA1 and CA2 fields and in lesser amounts of the dentate gyrus. The possibility that the therapeutic effects of hydergine administration on memory function in the elderly might be related to an effect on cholinergic muscarinic receptors of the ageing hippocampus is discussed.

Aging↗

PubMedDate not supplied

Vasoactive intestinal polypeptide-sensitive cyclic adenosine monophosphate generating system in the rat portal vein.

The effect of vasoactive intestinal polypeptide (VIP) on the 3'-5'-cyclic adenosine monophosphate (cAMP) generating system in membrane particles of rat portal vein was studied. In the presence of 10 microM GTP, VIP increased the concentration of cAMP in a dose-dependent manner. The removal of endothelium had no effect on cAMP production elicited by VIP. alpha- and beta-adrenergic as well as muscarinic receptor blocking agents did not inhibit VIP-dependent cAMP increase. Also various peptides, structurally analogous to VIP or active on portal vein smooth muscle, had no effect on cAMP production elicited by VIP. The present data, combined with those reported in the literature of an active relaxation of portal vein smooth muscle by VIP, suggest the existence of functionally active VIP receptors coupled to the adenylate cyclase system in the rat portal vein.

Animals↗

PubMedDate not supplied

Effect of dopamine on the cyclic adenosine monophosphate generating system in the rabbit internal carotid and middle cerebral artery.

The effect of in vitro addition of dopamine on the 3'-5'-cyclic adenosine monophosphate (cAMP) generating system of rabbit internal carotid and middle cerebral artery was studied. Dopamine increased cAMP levels in a dose-dependent manner in both arteries. The DA1-receptor antagonist SCH 23390 decreased the dopamine-elicited cAMP increase. On the contrary, the DA2-receptor antagonist L-sulpiride caused an increase in dopamine-dependent cAMP levels. The simultaneous addition of SCH 23390 and of L-sulpiride abolished any effect of dopamine on cAMP content. The DA2-receptor agonists bromocriptine and co-dergocrine decreased cAMP levels. The above findings indicate the existence in the rabbit internal carotid and middle cerebral artery of 2 types of dopamine receptors mediating respectively, the increase (DA1-effect) and the decrease (DA2-effect) of cAMP levels.

Animals↗

PubMedDate not supplied

Autoradiographic localization of the dopaminergic agonist 3H-dihydroergotoxine within the male reproductive system.

By the use of combined radioreceptor binding and autoradiographic techniques, we analyzed the anatomical localization of the dopaminergic agonist 3H-dihydroergotoxine in tissue sections of rat male sex organs. The drug was bound by smooth muscle cells of the deferent duct, seminal vesicles and prostate gland as well as by the glandular tissue of seminal vesicles and prostate gland. These data allow us to hypothesize that the effect of dopaminergic agonists on male sexual function may be due, at least in part, to a direct interaction with dopamine receptors present in the reproductive organs.

Animals↗

PubMedDate not supplied

[Anterior communicating artery: morphologic and structural aspects].

The gross anatomy of the anterior communicating artery has been studied in 40 adult brains removed at autopsy. We have observed 6 different anatomicals variant of the artery. A histological study shows that the wall of the artery is constituted with three layers: intima, media and adventitia. Moreover the structure of the arterial wall is different in some anatomicals variant. The findings are discussed.

Adult↗