Biomedical subjects

J Carretero

Publications and source records attributed to J Carretero.

At least 55 records · Page 3Linked to original sources

PubMed1994

In vitro and in vivo evidence for direct dopaminergic inhibition of VIP-immunoreactive pituitary cells.

In order to establish whether dopamine is involved in the regulation of immunocytochemical expression of VIP in pituitary cells, in vivo and in vitro studies were carried out on male rats after treatment with haloperidol and dopamine, respectively. In the in vivo studies, following intraventricular (third ventricle) administration of haloperidol, an increase in the total number of VIP-immunoreactive cells (p < 0.05) was observed; additionally, the cellular, cytoplasmic and nuclear areas were increased (p < 0.01). The in vitro studies demonstrated that dopamine induces a significant decrease (p < 0.05) in the total number of VIP-immunoreactive cells, which were smaller than the cells from the control dishes, because dopamine induces a significant decrease in their cellular, cytoplasmic and nuclear areas (p < 0.01). These results support the hypothesis that dopamine is a physiological inhibitor of pituitary VIP expression and suggest that dopamine modulates the auto- or paracrine effects of VIP in the rat pituitary.

Animals↗

PubMed1994

Changes in the neurosecretory axons of the neural lobe of the hypophysis of rats treated with met-enkephalin. An ultrastructural study.

Following administration of met-enkephalin into the third ventricle of rats of both sexes, an ultrastructural-morphometric study was carried out of the neural lobe of the hypophysis, comparing the results with those obtained in untreated animals, controls (injected intraventricularly with distilled water) and animals previously receiving naloxone intraperitoneally. In the untreated and control animals, both males and females, there was a high percentage (about 70%) of neurosecretory axons considered to have a normal morphology; after met-enkephalin administration, this percentage decreased and was accompanied by a rise (slightly more pronounced in the females) in the percentage of degranulated axons and a slight rise in axons with a morphology indicative of regenerative and degenerative phases. Previous administration of the opiate antagonist naloxone led to a rise in the number of axons in the degenerative phase with respect to the other groups of animals; this occurred in both sexes.

Animals↗

PubMed1994

Repercussion of craniopharyngioma on the morphology of the rostral wall of the III ventricle. A combined TEM and SEM study.

Using a combined scanning and electron microscope technique, the repercussion on the rostral wall of the III ventricle in a patient affected with a retrochiasmatic craniopharyngioma with growth in the ventricular direction were analysed. The apical surface of the ependymocytes was found to be free of cilia, although there were numerous microvilli. The most striking finding appreciated with the scanning electron microscope was the presence of bulbous protrusions towards the lumen of the ventricle; these were formed of cells with shapes, sizes and surface characteristics different from the rest of the ependyma, which appeared flattened. The ultrastructural study revealed the presence of large numbers of filaments and junction complexes both in the ependymal and subependymal cells. Additionally, the protruded zones corresponded to areas showing different degrees of cellular disorganization.

Cerebral Ventricles↗

PubMed1994

Immunohistochemical-morphometric study of the LH-adenohypophyseal cells following chronic treatment with met-enkephalin.

In order to test the possible effect of chronic treatment with met-enkephalin upon the LH-adenohypophyseal cells, an immunohistochemical-morphometric study was carried out in rats of both sexes receiving a daily dose of 40 micrograms of met-enkephalin intramuscularly over 15 days. Following the administration of the opioid, a drastic decrease in the cellular, cytoplasmic and nuclear areas when compared to the normal and control animals was detected. Morphologically, the main finding in males was the appearance of irregularly-shaped pseudovacuolated cells. On the other hand, in females a decrease in the intensity of reaction was found. These results strongly suggest a decrease in the activity of the LH-adenohypophyseal cells following chronic administration of met-enkephalin.

Animals↗

PubMed1993

Morphometric analysis of the hypoactivity of FSH-immunoreactive cells in estrogen-primed male rats.

In order to evaluate the repercussions of estradiol treatment on the morphology and activity of FSH-producing cells, an immunocytochemical and morphometric study was carried out in male rats treated chronically with estradiol, relating those findings to serum FSH levels at the time of sacrifice. Chronic administration of estradiol led to a decrease (p < 0.01) in serum hormone levels that was accompanied by a marked decrease in cellular size (p < 0.01) due to a decrease in nuclear and cytoplasmic area. Our findings suggest for the adult male rat an inhibitory effect on the synthesis and release of FSH following testicular atrophy induced by treatment with estradiol.

Analysis of Variance↗

PubMed1993

Ultrastructural and morphometric changes in somatotropic cells following intraventricular administration of Met-enkephalin to rats.

An ultrastructural and morphometric study of Kurosumi et al. (1986) on type 1 GH cells in adult Sprague-Dawley rats, after the intraventricular administration of Met-enkephalin, with or without prior intraperitoneal administration of naloxone, was carried out and then compared to the same cellular type of untreated animals and of animals intraventricularly treated with distilled water, used as controls. The study demonstrated an increase of cellular (p < 0.05) and nuclear (p < 0.05) areas, an enlargement and dilation of the cisternae of the Golgi complex, with an increase in the Golgi area (p < 0.01) and the immature granules (p < 0.01); a greater development of the rough endoplasmic reticulum and an increase in the number of exocytosis (p < 0.01) and, only in male rats, an increase in the mature secretory granules (p < 0.01). The prior administration of naloxone prevented the appearance of these changes and also produced an increase (p < 0.01) of the organelles involved in the crinophagic phenomenon. These results suggest that the opioids play a modulating role, stimulating the synthesis and secretion of GH, which affects the ultrastructural features of the hypophyseal GH cells.

Animals↗

PubMed1993

Combined TEM and SEM analysis of the rostral wall of the human III ventricle.

A combined morphological study using transmission and scanning electron microscopy was carried out on the central zone of the rostral wall of the III ventricle from a sample taken during the operation of a patient with a retrochiasmatic craniopharyngioma. Under the scanning electron microscope, the apical cell wall of the ependymocytes generally appeared folded and lack in cilia, but with numerous microvilli developed to different extents. The flat surface cells were scarce and were polygonal in shape and limited by 3-7 prominent edges. Ultrastructural analysis revealed the existence of several types of ependymocytes and subependymal epithelial cells arranged in different layers; in both layers the presence of abundant neurofilaments and intercellular junctions was striking.

Brain Neoplasms↗

PubMed1992

Partial coexistence of NADPH-diaphorase and somatostatin in the rat hypothalamic paraventricular nucleus.

Coexistence of NADPH-diaphorase (ND) activity and somatostatin (SRIF) immunoreactivity was studied in the paraventricular nucleus (PVN) of the rat hypothalamus by successive incubations of the same sections. ND was found in all PVN subdivisions, mainly in the magnocellular ones. SRIF was practically restricted to the parvicellular periventricular subdivision. Contrary to other brain regions where a wide SRIF-ND coexistence has been observed, the periventricular parvicellular subdivision was the only place of the PVN where some neurons colocalize both markers. The combination of the immunocytochemical and the histochemical labelings allows a further permanent and easy-to-perform parcellation of periventricular PVN neurons.

Animals↗

PubMed1992

Morphometrical variations of prolactin cells in response to prolonged and systemic administration of Met-enkephalin in female rats.

A stimulatory effect on prolactin secretion had been describe after acute and systemic administration of met-enkephalin, but the effects of this opioid after chronic administration has not been reported, and the response of mammotroph cells is not clear. As a complement to previous studies, a morphometric analysis (light and electron microscopy) was carried out on prolactin cells from female rats treated chronically with met-enkephalin. Clear features of cellular hyperactivity appeared after chronic and systemic administration of the opioid, and these persisted for two weeks. The changes consisted in increases of cellular, cytoplasmic and nuclear areas, volume and surface densities of the Golgi complex and rough endoplasmic reticulum, as well as the numbers of exocytotic figures. These morphological alterations were paralleled by an increase in serum prolactin levels as detected by RIA. It is concluded that the increase in the synthesis and secretory activity of prolactin cells following chronic and systemic administration of met-enkephalin is very similar to those observed after acute and intraventricular administration.

Analysis of Variance↗

PubMed1992

Immunocytochemical evidence of hypothalamic regulation of adenohypophyseal VIP in the male rat.

In order to check whether hypothalamic stimulatory or inhibitory factors exert any kind of modulation on the morphology of VIP-immunoreactive cells in the rat hypophysis, the transport of these towards the hypophyseal portal system was blocked by intraventricular administration of colchicine in adult male rats, thereafter performing a morphometric study after characterizing the VIP-immunoreactive adenohypophyseal cells by immunocytochemical techniques. Colchicine administration led to a significant increase (p < 0.01) in the number of reactive cells observed. These cells were characterized by a larger cellular area (p < 0.01), owing to increases in nuclear area (p < 0.05) and cytoplasmic area (p < 0.05). Their morphology became more regular, with a predominance of polygonal and oval cells. The results suggest that the VIP-reactive cells of the rat hypophysis are subject to a hypothalamic inhibitory influence and their activity increasing when the hypothalamic effect is interrupted by intraventricular administration of colchicine.

Animals↗

PubMed1992

NADPH-diaphorase activity in the hypothalamic magnocellular neurosecretory nuclei of the rat.

A histochemical study of the distribution of NADPH diaphorase activity in the hypothalamus of normal rats was carried out. Our study demonstrates the presence of NADPH-diaphorase activity in the circularis and anterior and posterior fornicals nuclei for the first time. Additionally, we confirm the presence of NADPH-diaphorase-stained neurons in the paraventricular (both magno- and parvicellular neurons) and supraoptic nuclei, as well as a population of isolated positive neurons (not included in any hypothalamic nuclei) located among the different nuclei. Because NADPH diaphorase has recently been shown to be a nitric oxide synthase, our study reveals a wide presence of this enzymatic activity in the hypothalamus of the rat.

Animals↗

PubMed1992

Calbindin D-28K- and parvalbumin-reacting neurons in the hypothalamic magnocellular neurosecretory nuclei of the rat.

The distribution of calbindin D-28K- and parvalbumin-reacting neurons in the hypothalamic magnocellular neurosecretory nuclei of the rat was studied using the avidin-biotin-immunoperoxidase method and highly specific monoclonal antibodies. Incubation with anticalbindin D-28K-antiserum revealed immunoreactive neurons in the following nuclei: supraoptic, paraventricular (both in the magnocellular and parvicellular regions), circularis, fornicals and medial forebrain bundle. Incubation with parvalbumin antiserum displayed immunoreactive neurons only in the circularis nucleus. Additionally, it was possible to observe scattered calbindin and parvalbumin immunoreactive neurons (which do not form part of the nuclei considered) located in the hypothalamic area between the supraoptic and the paraventricular nuclei, especially for the calbindin D-28K antiserum.

Animals↗

PubMed1992

Morphometric analysis of GH-immunoreactive cells after GH release induced by treatment with estrogen in adult male rats.

In order to elucidate the response of somatotropic cells to the influence of gonadal steroids on the regulation of growth hormone secretory patterns, a morphometric analysis was carried out on the GH-immunoreactive cells of adult male rats treated chronically with intramuscular injections of estradiol valerate. The morphometric and morphological results obtained were correlated to the serum levels of GH at the moment of sacrifice. Treatment with a daily dose of 125 micrograms of estradiol vaterate over 15 d was seen to lead to an increase (p less than 0.01) in the serum GH values accompanied by a decrease in the intensity of reaction of the GH-cells and, morphometrically, a reduction in their size (p less than 0.01) due to a decrease in the cytoplasmic area (p less than 0.01), but without significant changes in the nuclear area. Our results suggest that in male rats estrogens enhance the release of the intracellular GH pool but that they do not affect hormone synthesis to a great extent.

Analysis of Variance↗

PubMed1992

CaBP D-28k and NADPH-diaphorase coexistence in the magnocellular neurosecretory nuclei.

Coexistence of the calcium binding protein calbindin D-28k and NADPH-diaphorase activity was studied in the magnocellular secretory nuclei of the rat hypothalamus using both immunocytochemical and histochemical techniques. Coexistence was found in all the nuclei considered (supraoptic, paraventricular, circularis and fornicals nuclei) with the exception of the hypothalamic area situated between the supraoptic and the paraventricular nuclei. Since both stainings are reliable markers, not based upon the physiological characteristics at a given moment, our study provides a further characterization of the neurons in the magnocellular neurosecretory nuclei.

Animals↗

PubMed1992

Glial fibrillary acidic protein-like immunoreactive ependymal elements in the third ventricle of the rat. A study at different stages of development.

Using the peroxidase-antiperoxidase method a study was made of the cells immunoreactive to glial fibrillary acidic protein (GFAP) anti-serum in the ependyma of the third ventricle of the rat at different stages of growth. Most of the ependymal cells of the third ventricle were seen to be unreactive to this protein; however, it was sometimes possible to observe some GFAP-immunoreactive ependymocytes and occasionally other immunoreactive cellular types, such as tanycytes and supraependymal cells. Despite this, the most frequent localization of the elements immunoreactive to the protein adopted the shape of an immunoreactive subependymal band situated parallel to the ventricular wall. As the weights of the animals increased an increase in the elements immunoreactive to this protein could be observed in all the zones considered, there being no differences between the male and female animals.

Age Factors↗

PubMed1992

Estradiol influences the LH response to met-enkephalin. An immunocytochemical and morphometric study.

In order to test the possible role of estradiol in the response of the LH-adenohypophyseal cells to the administration of met-enkephalin in the albino male rat, an immunocytochemical (peroxidase-antiperoxidase), morphometric (cellular and nuclear areas and numerical density) and radioimmunoassay (LH serum levels at the moment of sacrifice) study was carried out. The intraventricular administration of met-enkephalin (150 micrograms in 25 microliters of distilled water) does not produce any changes in the parameters considered. However, when the animals were pretreated with estradiol (chronically, 15 days), met-enkephalin produced a significant decrease in all the parameters considered.

Animals↗

PubMed1992

Morphometric changes in GH-immunoreactive adenohypophyseal cells induced by intraventricular administration of colchicine to adult rats.

In order to elucidate whether the gender differences observed in the somatotropic cells of adult rats are mediated by hypothalamic neuropeptides, a morphometric analysis was made of the GH-immunoreactive cells of adult rats treated intraventricularly with colchicine. The morphometric and morphological findings obtained were correlated to the basal serum levels of GH at the time of sacrifice. Treatment with colchicine was seen to increase serum GH levels; this increase was accompanied by an increase in the intensity of the reaction of the GH-cells and, morphometrically, an increase in their size due to an increase in the nuclear area, but with no significant changes in the cytoplasmic area. The results suggest that in the absence of somatostatin and GRF the basal release of GH is elevated in a similar fashion in both sexes, in turn suggesting that gonadal steroids might act at hypothalamic level on the release of somatostatin and, indirectly, on the intracellular pool of GH and hormonal secretion.

Animals↗

PubMed1992

Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin.

Using the peroxidase-antiperoxidase immunocytochemical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.

Animals↗