Biomedical subjects

J A Vega

Publications and source records attributed to J A Vega.

At least 19 recordsLinked to original sources

PubMed1992

Localization of 5-hydroxytryptamine-like immunoreactive cells and nerve fibers in the rat female reproductive system.

The presence of 5-hydroxytryptamine (5-HT)-like immunoreactivity (IR) was studied in the rat female reproductive system using polyclonal antibodies directed against 5-HT. Moreover, 5-HT levels in the ovary, oviduct, uterus, and cervix were measured by high-pressure liquid chromatography with electrochemical detection. The highest 5-HT concentrations were found in the oviduct, followed in descending order by the cervix, the ovary, and the uterus. Most 5-HT-like IR was observed in the cytoplasm of mast cells. These cells were found in the connective tissue around the fimbria, in the oviduct, in the uterus, and in the ovary. Mast cells are clustered in the proximity of the parenchymal blood vessels. Moreover, a few 5-HT-like nerve fibers were found distributed mainly perivascularily in the uterine cervix and in the uterine horns as well as in the oviduct. IR nerve fibers were rarely seen within the ovary. The present data provide direct evidence that 5-HT in the female reproductive system not only is associated with mast cells but is located in nerve fibre-like structures as well. The functional significance of this probable 5-HT-ergic innervation of the female reproductive tract discovered in the present study should be clarified in future investigations.

Animals↗

PubMed1992

Oral choline alfoscerate counteracts age-dependent loss of mossy fibres in the rat hippocampus.

Mossy fibres represent a major intrahippocampal associative pathway. They consist of axons of granule cells of the dentate gyrus and show an age-dependent loss as do the granule cells of the dentate gyrus. The present study was designed to assess whether long-term treatment of rats with choline alfoscerate in their drinking water would be effective in countering the loss of mossy fibres and of granule cells occurring with aging. Choline alfoscerate is a precursor in the biosynthesis of brain phospholipids and increases the bioavailability of choline in nervous tissue. Male Sprague-Dawley rats of 18 months of age were divided into two groups. One group received a daily dose of 100 mg/kg choline alfoscerate for 6 months; the other group was used as an untreated control. Twelve-month-old untreated animals were used as a reference group. The area occupied by mossy fibres, as well as their density, was significantly reduced in 24-month-old control rats in comparison with 12-month-old rats. The same is true for the density granule cells of the dentate gyrus which was decreased by about 20% in the oldest animals. In choline alfoscerate-treated rats both the area occupied by mossy fibres and their density were significantly higher than in age-matched controls. Moreover, the number of granule neurons of the hippocampus was higher by about 7% in choline alfoscerate-treated than in control 24-month-old rats. The above data suggest that choline alfoscerate treatment counteracts some anatomical changes of the rat hippocampus occurring in old age.

Administration, Oral↗

PubMed1992

Changes in glutathione content and localization in rat heart as a function of age.

The influence of aging on glutathione levels and distribution in the heart was studied in male Sprague-Dawley rats of 3 (young), 12 (adult) and 24 (old) months of age using biochemical and histofluorescence techniques, respectively. Biochemical assays of reduced glutathione (GSH) in the right and left ventricles and in the septum showed a significant decrease in GSH levels in adult in comparison with young animals. No further changes were noticeable between adult and old rats. GSH histofluorescence revealed a rather homogeneous distribution of the product of histochemical reaction within both right and left atria in 3-month-old rats. In 12-month-old rats a reduction of GSH histofluorescence in comparison with younger animals was noticeable. The loss is more consistent in the epicardial portion of the right atrium and in the endocardial region of the left atrium. In the atria of 24-month-old rats GSH reactivity was homogeneously distributed throughout the atrial wall and was significantly lower than in young or adult rats. In 3-month-old rats GSH histofluorescence was slightly lower in the epicardial than in the endocardial portions of both ventricles. In adult rats a significant decrease of GSH histofluorescence was noticeable in comparison with 3-month-old rats. The loss is particularly pronounced within the endocardial region of the left ventricle. In 24-month-old rats GSH histofluorescence showed no significant differences between adult rats. However, GSH was more homogeneously distributed throughout the ventricular wall than in adult animals. The significance of these data is discussed in relation to the role that GSH plays in protecting the myocytes against free radical damage.

Aging↗

PubMed1992

Immunohistochemical localization of epidermal growth factor and its receptor during odontogenesis in the rat.

The expression of epidermal growth factor (EGF) and epidermal growth factor receptor (EGFr) in developing teeth has been immunohistochemically studied in rat embryos (E-16 to E-21). Both EGF and EGFr showed a similar pattern of distribution. A very weak immunostaining was observed in the dental germ cells during the bud, cap, and bell teeth stages, as well as in few ectomesenchymal cells. In developed, but not erupted teeth, a moderate immunoreactivity for EGF and EGFr was present in the odontoblasts, in the ameloblasts and in the internal epithelial cells, but it was stronger in the dentine. In addition, the presence of EGF/EGFr was also observed in the intercalated ducts of salivary glands, primarily the submaxillary gland, in the maxillary bone cells, and in the cells of the peripheral and central nervous system. These results suggest that EGF has little or no effect during the early periods of tooth differentiation, whereas it is probably involved in the production of dentine. Moreover, EGF/EGFr seem to participate in the maturation and differentiation of other embryonic tissues such as tissues of the nervous system and bone.

Ameloblasts↗

PubMed1992

Nerve growth factor receptor immunoreactivity in non-nervous structures of the adult rat brain.

The non-neuronal distribution of nerve growth factor receptors (NGFr) in the adult rat brain was investigated immunohistochemically using an anti-NGFr monoclonal antibody (192-IgG). In addition to the neurons known to be NGF-dependent or containing NGF binding-sites, a moderate to strong NGFr immunoreactivity was observed in several non-nervous tissues such as the ependymal cells, the epithelial cells of the choroid plexus, the leptomeninge and the cerebral blood vessels. Vascular immunoreactivity for NGFr occurs in the adventitia and muscular layers of the large arteries (circle of Willis) and, apparently, in all the wall layers of the intermediate or small (pial-arachnoid) arteries. The present results provide direct evidence for the presence of non-neuronal NGFr in the brain of adult rats, and suggest a possible involvement of NGF in roles other than those classically thought.

Animals↗

PubMed1992

Expression of nerve growth factor receptor immunoreactivity in the rat choroid plexus.

The presence and localization of nerve growth factor receptors (NGFr) in the choroid plexus of the adult rat has been investigated immunohistochemically using an anti-rat NGFr monoclonal antibody (192-IgG). A moderate to strong immunoreaction was observed in the epithelial cells of the choroid plexus, whereas the choroidal blood vessels and connective tissue remained unlabelled. Moreover, no sex-differences were encountered in the NGFr immunoreaction intensity and Bouin fixative was more effective than 10% formaldehyde evidenciating the NGFr immunostain. Occasionally, ependymal cells displaying NGFr immunoreactivity were observed. Present data demonstrate that the choroid plexus of the rat contain NGFr, probably low-affinity NGFr, and suggest an involvement of NGF in the regulation of cerebrospinal fluid secretion, but the importance of these findings, if any, must be investigated in future studies.

Animals↗

PubMed1992

Nerve growth factor receptor (NGFR) immunoreactivity in skeletal muscles of the rat.

The peroxidase-antiperoxidase (PAP) method, and a specific monoclonal antibody (192-IgG) were used to determine the localization of nerve growth factor receptor (NGFr) in the skeletal muscles of the adult rats. The rectus femoris and the gastrocnemius (medialis and lateralis) muscles were analyzed. Occurrence of NGFr immunoreactivity was observed in: 1) a subpopulation of myelinated nerve fibers within muscle nerve trunks; 2) the vascular adventitia and nerve-like profiles around the blood vessels; 3) the outer capsule and the surface of the intrafusal muscle fibers of muscle spindles. Conversely, images, suggesting the presence of NGFr on muscle fibers or in motor end-plates, were not found. Our results suggest the presence of NGF-binding sites in sensory and sympathetic nerve fibers, and/or their target tissues localized on the skeletal muscles of the rat, whereas the motor nerve fibers lack of NGFr. The dependence of sympathetic neurons, proprioceptive primary sensory neurons, and motoneurons innervating the mammalian muscles upon NGF or other neurotrophic factors is discussed.

Animals↗

PubMed1991

Age-related structural changes in the rat cerebellar cortex: effect of choline alfoscerate treatment.

The influence of ageing and of 3 months choline alfoscerate treatment on age-related microstructural changes in cerebellar cortex was studied in 3-, 12- and 24-month-old male Sprague-Dawley rats. The number of Purkinje and granule neurons, the density of Nissl bodies in the cytoplasm of Purkinje and granule neurons and the density of silver-gold impregnated fibres within molecular and granule cells layers were assessed by neurohistological and neurohistochemical techniques associated with microdensitometry and quantitative image analysis. The number of Purkinje and granule neurons was approximately the same in rats of 3 and 12 months and significantly decreased in 24-month-old animals. The density of Nissl bodies and of fine processes of silver-gold impregnated fibres were greatest in the cerebellar cortex of rats of 12 months of age, followed in descending order by 3- and 24-month-old rats. Both the density of Nissl bodies and of silver-gold impregnated fibres were significantly lower in the cerebellar cortex of the oldest age group considered in comparison with the young and middle age groups. Treatment with choline alfoscerate, a precursor in the biosynthesis of brain phospholipids which increases bioavailability of choline in the nervous tissue, noticeably reduced the loss of Purkinje and granule neurons in rats of 24 months. Moreover, it restored the density of Nissl bodies in the cytoplasm of Purkinje and granule neurons as well as the density of silver-gold stained fibres in the molecular and in the granule cells layers to values not significantly different from those found in rats of 3 months. These findings suggest that choline alfoscerate treatment may be effective in counteracting the age-dependent disarrangement of rat cerebellar cortex. The possible mechanisms of action of the compound on the microstructural changes of cerebellar cortex occurring with age are discussed.

Aging↗

PubMed1991

Autoradiographic localization of dopamine receptors in rat cerebral blood vessels.

Combined in vitro radioreceptor binding and autoradiographic techniques were used to analyze the pharmacological profile and the anatomical localization of dopamine (DA) DA1 and DA2 receptor sites in the arteries and arterioles of the pial-arachnoid membrane in the rat. [3H]SCH 23390, used as a ligand of DA1 receptors, was bound by sections of rat cerebral vessels in a manner consistent with the labeling of DA1 receptors, with a value of 2.2 nM for the dissociation constant (Kd) and of 68.4 fmol/mg protein for the density of binding sites (Bmax). The ligand was bound primarily by the medial layer of cerebral arteries. The density of silver grains developed after exposure of cerebral vessel sections to [3H]SCH 23390 was unchanged after chemical sympathectomy with 6-hydroxydopamine (6-OHDA) and was not significantly different in either the circle of Willis arteries or in the pial-arachnoid arteries and arterioles. [3H]Spiroperidol was used as ligand of DA2 receptors in the presence of ketanserin to block the possible binding to 5-HT2 receptors. [3H]Spiroperidol was bound by sections of rat cerebral vessels in a manner consistent with labeling of DA2 receptors, with Kd and Bmax values of 1.9 nM and 39.8 fmol/mg protein, respectively. The ligand was bound primarily by the adventitia and the adventitial-medial border as well as by the intimal layer of cerebral arteries. The accumulation of adventitial and adventitial-medial silver grains developed after exposure of cerebral vessels sections to [3H]spiroperidol did not occur in 6-OHDA-treated animals. In contrast, chemical sympathectomy was without effect on the density of intimal silver grains. The density of adventitial silver grains was higher in the anterior than in the posterior circle of Willis and pial-arachnoid arteries and arterioles, as well as in the pial-arachnoid arteries and arterioles than in circle of Willis arteries. These findings indicate the existence of both DA1 and DA2 receptor sites in the rat cerebrovascular tree.

Animals↗

PubMed1991

Presence of catecholamine-related enzymes in a subpopulation of primary sensory neurons in dorsal root ganglia of the rat.

The presence of enzymes (tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (D beta H)) and enzymatic activities (monoamino oxidase, (MAO)) related to catecholamine synthesis and degradation have been investigated in cervical, thoracic and lumbar dorsal root ganglia (DRG) of adult male rats using immunohistochemical and enzyme histochemical techniques, respectively. A small population (between 2-4%) of TH-like immunoreactive and MAO positive neurons was found. They were small in diameter (18 +/- 2 microns), predominate in lumbar DRG and did not display D beta H-like immunoreactivity. These sensory neurons which are likely catecholaminergic were insensitive to systemic administration of capsaicin and 6-hydroxydopamine. Colchicine administration caused an increase of TH-like immunoreactivity and MAO activity. Pargyline produced an increase in TH-like immunoreactivity and the disappearance of MAO activity. The possible dopaminergic nature of the subpopulation of DRG sensory neurons investigated in the present study is discussed.

Animals↗

PubMed1991

Immunohistochemical study of sensory nerve formations in human glabrous skin.

The sensory nerve formations (or corpuscles) of normal human glabrous skin from hand and fingers, obtained by punch biopsies, were studied by the streptavidin-biotin method using monoclonal antibodies directed against neurofilament protein (NFP), S-100 protein, glial fibrillary acidic protein (GFAP), cytokeratins, and vimentin. NFP immunoreactivity (IR) was observed in the central axons of most sensory formations, while S-100 protein IR was restricted to non-neuronal cells forming the so-called inner cells core or lamellar cells. Furthermore, vimentin IR was found in the same cells of Meissner's and glomerular corpuscles. None of the sensory nerve formations were stained for GFAP or keratin. The present results suggest that the main nature of the intermediate filaments of the non-neuronal cells of sensory nerve formations from human glabrous skin is represented by vimentin and not by GFAP. Thus, our findings suggest that lamellar and inner core cells of SNF are modified and specialized Schwann cells and not epithelial or perineurial derived cells.

Adult↗

PubMed1991

Study of the rat TSH-producing cells after met-enkephalin treatment: effects of dopamine antagonists.

The effects of single and repeated doses of met-enkephalin (Met-E) on the ultrastructure and TSH-like immunoreactivity (IR) of pituitary TSH-producing cells, and TSH plasma levels in male rats and the influence of pretreatment with a dopamine antagonist, haloperidol, on these, were evaluated. Both acute and repeated Met-E administration produced changes in TSH cells consisting of: an increase in TSH-like IR, enlargement and dilation of RER and Golgi apparatus, size-increase of secretory granules, and the presence of a variable number of cytoplasmic vacuoles. The ultrastructural changes were more evident in the chronically treated animals, whereas no differences were found in IR-intensity between both Met-E treated groups. Haloperidol alone modifies neither ultrastructure nor TSH-like IR of TSH producing cells, but it prevented the Met-E produced changes. On the other hand, Met-E treatment resulted in a decrease of TSH plasma levels, but being significant only in the acutely injected animals. No variations were produced by haloperidol alone, but it prevented the decrease of TSH plasma levels stimulated by Met-E. Our results suggest that Met-E plays a role in the release of TSH, and that dopamine is implicated in this process. The possible mechanisms through which Met-E influences TSH secretion are discussed.

Animals↗

PubMed1991

Ultrastructural, immunocytochemical and morphometric studies of pituitary prolactin cells after chronic administration of met-enkephalin.

The effects of chronic administration of met-enkephalin (40 micrograms/day, for 20 days) on the pituitary prolactin cells of Wistar male rats were studied at the light (PAP-immunohistochemical for PRL demonstration technique) and electron microscopy levels. The D. CIRCLE (mean diameter), D. MAX (maximum diameter) and FORM PE (circular factor of form; irregularity degree) form secretory granules, as well as their percent distribution, were also evaluated. The cellular alterations were variable. Most prolactin cells showed an increase in immunohistochemical reaction. At the electron microscope level the prolactin cells showed an enlargement and swelling of the RER and Golgi apparatus. The secretory granules were bigger and more spherical in experimental than in untreated and control animals. A number of cells showed a variable number of cytoplasmic vacuoles or a large central vacuole formed from dilated RER-cisternae. The authors discuss the possible mechanism whereby met-enkephalin exerts a control on prolactin cells.

Animals↗

PubMed1991

Effects of morphine on the pituitary-thyroid axis: morphological and analytical studies.

The morphology of the TSH-producing pituitary cells and the thyroid gland, and plasma TSH, T3 and T4 hormone levels, were studied in normal rats, in rats treated with 10 micrograms morphine (M) and in M-treated animals pretreated with naloxone (Nx) (10 mg/kg). Morphological changes in the pituitary TSH cells and thyroid cells of M-treated animals were minimal and were not modified by Nx pretreatment. Plasma TSH levels in M-treated animals showed a significant decrease (P less than 0.05), which was not blocked by Nx pretreatment. No significant changes in plasma T3 or T4 levels were found in either experimental group.

Animals↗

PubMed1991

Immunohistochemical localization of S-100 protein subunits (alpha and beta) in dorsal root ganglia of the rat.

The distribution of S-100 protein and their subunits (alpha and beta) in lumbar dorsal root ganglia of adult rat was investigated immunohistochemically using monoclonal antibodies against the S-100 protein, alpha-subunit and beta-subunit of S-100 protein. The conventional S-100 protein antibody stained both neurons (large and intermediate in size; 20.3% and 41 +/- 3.2 microns of diameter) and glial cells (satellite cells and Schwann cells). The immunoreaction for the alpha-subunit was observed in the perikarya of some large and intermediate sized neurons (17.2%, 45.6 +/- 6.1 microns of diameter), satellite cells and Schwann cells, whereas the beta-subunit immunoreactivity was found principally in glial cells, and in a scarce number of large and intermediate sized neurons (2.8%, 43.3 +/- 5 microns of diameter) Our results demonstrate that a subpopulation of large and intermediate sized neurons of lumbar DRG contain alpha- and beta-subunits of S-100 protein, being alpha-subunit predominant. Furthermore, the satellite glial and Schwann cells contain also the two subunits but mainly beta-subunit. These data confirm previous studies about the presence of S-100 protein in neurons of the central and peripheral nervous system.

Animals↗

PubMed1990

Age-dependent changes of the sympathetic innervation of the rat kidney.

The influence of aging on the sympathetic innervation of the kidney was studied in 3- (considered to be young), 12- (considered to be adult) and 24- (considered to be old) month-old male Sprague-Dawley rats by means of high pressure liquid chromatography with electrochemical detection, catecholamine histofluorescence and acetylcholinesterase (AChE) histochemistry. Body and kidney weights were significantly increased in adult in comparison with young rats. No further increase of either body or kidney weight was appreciated in old rats. Noradrenaline levels were increased by about 48% in adult rats and were decreased in old rats (by approx. 22% vs. young and 60% vs. adult). The density of perivascular noradrenergic fibres was significantly increased in adult rats and decreased in old animals. The percentage of kidney glomeruli supplied by AChE-positive nerve fibres is also remarkably increased in 12-month old rats and decreased in 24-month-old rats. The present data indicate that there is a striking increase in the expression of sympathetic innervation of rat kidney at 12 months of age followed by a significant decrease in the expression of innervation in old age. These changes are discussed in relation to the age-dependent impairment of renal function.

Acetylcholinesterase↗

PubMed1990

Expression of glial fibrillary acidic protein-like and S-100 protein like immunoreactivities on cartilages of the rat vestibulum nasi. Post-natal development changes.

The cartilages of vestibulum nasi in rats of different ages (newborns, 1 week, 1 month and 12 months old) were studied immunohistochemically using monoclonal antibodies against glial fibrillary acidic protein (GFAP) and S-100 protein. The immunoreaction for both GFAP and S-100 protein results positive in a variable number of chondrocytes. The number of chondrocytes displaying GFAP-like immunoreaction does not change during development and maturation, whereas those showing S-100 protein-like immunoreactivity increase from birth to the adult state. The formation of cartilaginous tissue from neuroectodermic cells of neural crest has been postulated by several authors and our results strongly support these opinions; moreover, according to present findings S-100 protein could be involved in chondroid tissue formation.

Animals↗

PubMed1990

Immunohistochemical study of the sensory formations in the glabrous skin of the rat.

The presence of some cytoskeletal proteins related to the intermediate filaments glial fibrillary acidic protein -GFAP and vimentin) and S-100 protein has been investigated in sensory formations of the glabrous skin of the rat. A positive reaction both for S-100 protein and vimentin was found in the inner core and related cells of glomerular and simple sensory corpuscles; in contrast, no positive reaction was shown for GFAP. The authors discuss these results on the basis of the glial origin of the inner core and related cells in sensory formations.

Animals↗