Search PubMed⌕ Search

Biomedical subjects

F Amenta

Publications and source records attributed to F Amenta.

At least 217 records · Page 12Linked to original sources
PubMed1988

Capsaicin-sensitive tachykinin-like immunoreactivity in the thymus of rats and guinea-pigs.

Capsaicin-sensitive, substance P-like immunoreactivity (SP-LI) has been detected recently in rat thymus. Other tachykinins are frequently present with SP. In the present study, tachykinin-like immunoreactivity (TK-LI) was measured in guinea-pig, rat, mouse and hamster thymus with the amount detectable being greatest in guinea-pig, less in rat and least in mouse; it was not detectable in hamsters. In guinea-pig and rat thymus, but not in mouse, TK-LI was markedly reduced by pretreatment with capsaicin. TK-LI levels correlated significantly with those of SP-LI in both guinea-pig and rat thymus. High-performance liquid chromatography (HPLC) fractions considered to represent neurokinin A, eledoisin and neuropeptide K were present in guinea-pig thymus but only the first two were present in rat thymus.

Animals↗
PubMed1988

Increase in substance P levels in the lung of old rats.

Substance P levels in the lung of young (3-month-old), adult (12-month-old), senescent (20-month-old) and aged (28-month-old) male Wistar rats were determined by radioimmunoassay. Levels of substance P were constant until 28 months of age when these become significantly higher (approximately more than 2 times, p less than 0.001) than the values found in younger rats. Whether the increase of substance P content in the lung of old rats may reflect changes in the density of substance P containing nerve fibres or in the content of the peptide in single nerve fibres is discussed.

Aging↗
PubMed1988

Effect of prolonged co-dergocrine mesylate treatment on choline acetyltransferase levels in rat cerebral cortex after lesioning of the nucleus basalis magnocellularis (of Meynert).

The effects of monolateral lesions of the nucleus basalis magnocellularis (of Meynert) and of 1 or 4 weeks of co-dergocrine mesylate treatment (0.1 or 0.6 mg/kg) on choline acetyltransferase activity in rat frontal, parietal and occipital cortex were studied. According to the literature, ibotenic acid-induced lesions of the nucleus basalis magnocellularis cause a significant decrease in choline acetyltransferase activity in frontal and parietal cortex, but had no effect on enzyme activity in the occipital cortex or cortical areas controlateral to the lesion. Co-dergocrine administration caused, after 4 weeks of treatment, a dose related increase of choline acetyltransferase activity in the frontal and parietal cortex in the lesioned side. In contrast, it had no effect on the enzyme activity in the other cortical regions studied. The possible significance of the increased choline acetyltransferase activity elicited by co-dergocrine mesylate in cerebral cortex areas sensitive to nucleus basalis magnocellularis lesions is discussed.

Animals↗
PubMed1988

Increase in perivascular noradrenergic nerve density and decrease in acetylcholinesterase-positive sympathetic nerve density in the kidneys of spontaneously hypertensive rats.

The density and pattern of sympathetic nerve fibres in the kidneys of 16-week-old spontaneously hypertensive rats (SHR) and of control age-matched normotensive Wistar-Kyoto (WKY) rats were studied by catecholamine histofluorescence and acetylcholinesterase histochemical techniques. Varicose noradrenergic fibres primarily supply renal vasculature and were concentrated in small arteries and in afferent glomerular arterioles. The number and the density of these nerve fibres were increased in SHR. Acetylcholinesterase-positive nerve fibres were distributed to the renal vascular tree in the same way as the noradrenergic nerves and disappeared after chemical sympathectomy, suggesting their sympathetic nature. Acetylcholinesterase-positive perivascular nerve fibres were decreased in SHR. The possible significance of the two directional behaviour of sympathetic nerves (noradrenergic and acetylcholinesterase-positive) in the kidneys of SHR is discussed.

Acetylcholinesterase↗
PubMed1988

Autoradiographic localization of the GABAA receptor agonist [3H]-muscimol within rat kidney.

By the use of combined radioreceptor binding and autoradiographic techniques, the pharmacological characteristics of (3H)-muscimol binding and the localization of the label were studied. (3H)-Muscimol was bound by sections of rat kidney in a manner consistent with the existence of specific gamma-aminobutyric acid 'A' (GABAA) receptors with KD and Bmax values of 23.7 nmol/l and 1.15 pmol/mg tissue, respectively. (3H)-Muscimol was bound by convoluted tubules of the renal cortex and by the collecting tubules. Our findings demonstrating the existence of recognition sites for the GABAA receptor agonist muscimol in the kidney suggest that GABA has a role in renal function.

Animals↗
PubMed1988

GABAA receptor sites modulating catecholamine secretion in the rat adrenal gland: evidence from 3H-muscimol autoradiography and in vivo functional studies.

The occurrence and distribution of specific 3H-muscimol binding sites, most probably identical with A type gamma-aminobutyric acid (GABA) receptors, were studied in sections of the rat adrenal gland by light microscope autoradiography. Specific binding was found primarily in the adrenal medulla, in association with chromaffin cells. A limited number of binding sites was also observed within the adrenal cortex. In urethane-anaesthetized hexamethonium-pretreated rats, intravenous GABA produced a set of 'excitatory' cardiovascular effects (increase in heart rate, force of contraction and blood pressure) which were mimicked by intravenous muscimol but not by intravenous baclofen, and were antagonized by pretreatment with bicuculline. The cardiovascular excitatory effects of intravenous GABA were unaffected by reserpine pretreatment, markedly reduced by administration of phentolamine plus propranolol, and almost completely abolished by adrenalectomy. Our findings indicate the presence of GABA receptor sites on adrenal chromaffin cells, whose excitation can produce changes in cardiovascular function.

Adrenal Cortex↗
PubMed1988

Effect of ageing on the nerve fibre population of rat optic nerve.

The age-related changes in the number and density of optic nerve fibres were studied in 3-month-old (young), 12-month-old (adult), 20-month-old (senescent) and 30-month-old (aged) male Wistar rats. Two-micrometer-thick resin-embedded transverse sections of the optic nerve of animals of the different age groups were stained with toluidine blue and examined under a light microscope at low (X5) and high (X500) magnification. The optic nerve cross-sectional area and the number of nerve fibres with diameters shorter or longer than 1 micron were assessed by means of computerized image analysis. Optic nerve cross-sectional area is constant in young and adult rats, but is increased in senescence. The number of optic nerve fibres with a diameter less than 1 micron is decreased by about 18 and 12% in 20-month-old rats versus 3- and 12-month-old rats, respectively. The number of these nerve fibres is decreased by about 43, 39 and 30% in 30-month-old rats versus 3-, 12- and 20-month-old animals, respectively. In contrast no age-dependent changes were observed in nerve fibres with diameters greater than 1 micron. The present data suggest that age-related impairment of nerve cell population described by other authors in rat retina and visual cortex occurs also at the level of the optic nerve.

Aging↗
PubMed1988

Effects of long-term Hydergine administration on lipofuscin accumulation in senescent rat brain.

The effects of ageing and of 6 months of Hydergine treatment on lipofuscin deposition within the cytoplasma of pyramidal neurons of rat prefrontal cortex, hippocampus (fields CA1 and CA3) and of Purkinje neurons were assessed microfluorimetrically. No lipofuscin autofluorescence was detected in the nerve cell populations of 3-month-old rats, but lipopigment had accumulated in nerve cell bodies of 16-month-old animals and increased significantly thereafter in rats of 22 months of age. In 22-month-old rats, Hydergine administration (0.6 and 1 mg/kg p.o.) started at 16 months caused a significant dose-related decrease in lipofuscin accumulation within the cytoplasm of the various kinds of nerve cells examined.

Aging↗
PubMed1988

Similarity of vasopressin receptors in seminal vesicles and renal medulla of pigs.

To test the hypothesis that the vasopressin receptors found in seminal vesicles are similar to those present in the renal tubules competition experiments were performed with vasopressin and several analogues with different specificities for the V1 and V2 subtypes of vasopressin receptor. Autoradiographic studies were carried out on sections from seminal vesicles and kidney to identify the cellular target of vasopressin. Vasopressin receptors in renal medulla and seminal vesicles of pigs shared the same rank order of potency for vasopressin and its analogues and were localized in the epithelium of the seminal vesicles and in collecting tubules of renal medulla. These results strongly suggest that the vasopressin receptors present in kidney and seminal vesicles belong to the same subtype, V2, of vasopressin receptor.

Animals↗
PubMed1988

Effect of long-term treatment with acetyl-L-carnitine on structural changes of ageing rat brain.

The effects of long-term treatment (11 months) with acetyl-L-carnitine (75 mg/kg daily) on the morphology of brain and optic nerve was studied in 16 senescent (22-month-old) Wistar rats (nine untreated, seven treated). Five young rats (aged 3 months) were used for comparison. Senescence was found to cause a structural disorganization of cerebral cortex, hippocampus and cerebellar cortex, and a decrease in the volume densities of the pyramidal neurons of layers 2 and 5 of the prefrontal cortex. An impaired myelination of the pyramidal tract and of the optic nerve was also observed. Besides improving the structural organization of the cerebral areas under study, treatment with acetyl-L-carnitine increased the volume densities of pyramidal neurons of the prefrontal cortex layers under observation. It must be added that myelination of the pyramidal tract and optic nerve was found to be less impaired after acetyl-L-carnitine administration.

Acetylcarnitine↗
PubMed1988

The peptidergic innervation of the guinea pig uterine artery in pregnancy.

The influence of pregnancy on the density and pattern of the peptidergic innervation of the guinea pig uterine artery was studied. Whole mount stretch preparations of the uterine artery from estrus and late pregnant guinea pigs were processed for the immunohistochemical demonstration of neuropeptide Y (NPY)-, vasoactive intestinal polypeptide (VIP)-, calcitonin gene-related peptide (CGRP)- and substance P (SP)- immunoreactive nerve fibres. In late pregnancy the density of NPY- and CGRP- containing nerve fibres was remarkably decreased, while that of VIP- and SP- immunoreactive nerves showed a moderate reduction. The meaning and the possible physiological relevance of the decreased density of peptide-immunoreactive nerves in the uterine artery in late pregnancy are discussed.

Animals↗
PubMed1987

Autoradiographic localization of the GABAA receptor agonist [3H]muscimol in rat cerebral vessels.

By the use of combined in vitro radioreceptor binding and autoradiographic techniques with [3H]muscimol as a ligand, we analyzed the distribution of GABAA receptor sites in the arteries of the circle of Willis as well as in the arteries and arterioles of the pial-arachnoid membrane in the rat. [3H]Muscimol was bound by sections of rat cerebral vessels in a manner consistent with the existence of GABAA receptors, with Kd and Bmax values of 46 nM and 0.60 pmol/mg tissue respectively. [3H]Muscimol was bound by the medial layer of cerebral arteries, while no specific binding was observed in the intima, the adventitia and the adventitial-medial border. These findings suggest that the vasodilatory action of GABA on in vitro preparations of cerebral vessels is mediated by muscular receptor sites. The posterior cerebral arteries are richer in [3H]muscimol binding sites than the anterior ones. Pial-arachnoid arterioles, which are of critical importance in controlling local cerebral blood flow, did not exhibit any significant binding of [3H]muscimol. These results may explain the difficulty in manipulating pharmacologically the cerebral tissue perfusion in intact animals using GABAergic agonists.

Animals↗
PubMed1987

Dopamine receptors mediating the stimulation and the inhibition of adenylate cyclase in rat prostate gland.

The effect of dopamine on the 3',5'-cyclic adenosine monophosphate (cAMP) generating system of membrane particles of rat prostate gland was studied. Dopamine increased the concentration of cAMP in a dose-dependent manner. The selective D1 receptor inhibitor SCH 23390 caused a decrease in dopamine-elicited cAMP levels. Any effect of dopamine on prostatic cAMP concentration was abolished by the simultaneous addition to the incubation medium of SCH 23390 and of the D2 receptor blocking agent (-)-sulpiride. Also the D2 receptor agonist bromocriptine decreased cAMP levels. The present data indicate the existence, in the rat prostate gland, of two types of dopamine receptors mediating, respectively, the activation (D1 effect) and the inhibition (D2 effect) of adenylate cyclase activity.

Adenylyl Cyclases↗
PubMed1987

Cutaneous lesions in capsaicin-pretreated rats. A trophic role of capsaicin-sensitive afferents?

1. The time course and regional distribution of 'spontaneous' cutaneous lesions in rats desensitized to capsaicin as newborns was correlated to behavioural observations and regional distribution of substance P-like immunoreactivity (SP-LI) and tachykinin-like immunoreactivity (TK-LI) in various skin areas. 2. 'Spontaneous' skin lesions in the form of wounds, scabs and areas of alopecia were observed in 80-90% of rats desensitized to capsaicin. No major sex-related differences were observed with regard to incidence and distribution of the lesions with the possible exception of a lesser tendency to bilateral lesions in female rats. 3. 'Spontaneous' skin lesions were almost restricted to the head: the areas most frequently affected were snouts, periocular and retroauricular regions and ventral area of the neck. 4. No major differences were observed between capsaicin- or vehicle-treated animals in spontaneous or novelty-induced grooming as well as in open-field gross behaviour. Likewise, no differences were observed in the mouse-killing behaviour. 5. Both SP-LI and TK-LI in various skin areas were significantly reduced by systemic capsaicin pretreatment. The rank order of various skin areas for SP-LI or TK-LI levels was: snouts greater than thigh greater than neck greater than abdomen approximately equal to retroauricular region. 6. Intradermal injection of Arg-neurokinin B, a potent and water soluble derivative of neurokinin B, produced a similar plasma extravasation (Evans blue leakage technique) in the skin of vehicle- or capsaicin-pretreated rats. 7. In capsaicin-desensitized rats fur regrowth (measured at abdominal level, 28 days after shaving) was significantly less than in vehicle-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Vasoactive intestinal polypeptide levels and distribution in the penis of old rats.

Vasoactive intestinal polypeptide (VIP) levels and distribution were studied in the penis of young-adult (3-month-old) and old (30-month-old) Wistar rats by radioimmunoassay and immunofluorescence. No significant changes in tissue VIP concentrations or distribution occurred in the penis of old rats compared to young-adult rats. The present data indicate that the age-related impairment of male sexual function is not dependent on modifications of the VIP-ergic innervation of penile tissue.

Aging↗
PubMed1987

Enzyme histochemistry of the choroid plexus in old rats.

The influence of ageing on the metabolic profile of lateral ventricle choroid plexus epithelial cells from young (3-month-old) and aged (26-month-old) male Wistar rats was studied using enzyme histochemical techniques. The following enzymatic activities related to energy transduction were examined: lactate-(LDH) and succinate- (SDH) dehydrogenases; NADH2-tetrazolium reductase (NADHD) and alpha-glycerophosphate-dehydrogenase (GPDH). The intensity of enzymatic staining within single choroid plexus epithelial cells from young and old animals was assessed microphotometrically. In the choroid plexus epithelial cells of young rats NADHD was the enzymatic activity more heavily stained; cell levels of LHD and GPDH were approximately the same and SDH reactivity was less intense. In old age LDH was reduced by 9.3%, SDH was reduced by 26.1%, NADHD was reduced by 8.6% and GPDH was reduced by 3.6%. The possibility that impaired energy transduction mechanisms at the level of choroid plexus epithelium in old age may influence functional activity of the choroid plexus is discussed.

Aging↗
PubMed1987

Enzyme histochemistry of monoamine oxidase in the heart of aged rats.

The distribution of monoamine oxidase types A and B in the heart of young (3-month-old) and aged (26-month) Wistar rats was studied by histochemical methods. In young rats, MAO activity was higher in the left ventricle than in the right. Enzyme reactivity was present within both muscle cells and the blood vessel wall. Histochemical staining was abolished by clorgyline administration. In the heart of aged rats, we observed a very remarkable increase of clorgyline sensitive MAO activity primarily at the level of myocardial cells. The right ventricle showed the highest increase of MAO reactivity.

Aging↗