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J Carretero

Publications and source records attributed to J Carretero.

At least 73 records · Page 4Linked to original sources
PubMed1992

Met-enkephalin induces fast synaptic plasticity of magnocellular neurons in the rat supraoptic nucleus.

A morphometric-ultrastructural study was made of the supraoptic nucleus of rats of both sexes following central administration of met-enkephalin. Ten minutes after met-enkephalin treatment the number of axo-somatic synapses was significantly increased. This effect was more pronounced in female rats than in males and could be prevented by preceding administration of naloxone. Animals that received naloxone followed by met-enkephalin showed a dilation of the rough endoplasmic reticulum into a vesicular shape. Our results provide preliminary evidence for a fast remodeling of synaptic input to magnocellular hypothalamic neurons. It is likely that the known inhibitory action of opioids on the hypothalamo-neurohypophysial system is partly mediated by this plasticity.

Animals↗
PubMed1991

Estrogenic modulation of met-enkephalin-induced prolactin secretion in rats.

In order to elucidate the possible role of estrogens in the sex-dependent modulation of met-enkephalin-induced prolactin secretion, and the cellular response at adenohypophyseal level, analyses of serum prolactin levels together with a morphometric study of prolactin-immunoreactive cells were carried out following intraventricular administration of the opioid to estrogen-primed male rats. Administration of the opioid led to an increase in the serum levels of the hormone and, morphometrically, a significant increase in the cellular, cytoplasmic and nuclear areas was observed. When naloxone was administered previously, the above, mentioned changes did not appear, and the values found were similar to those observed in the animals treated only with estrogens. The results suggest that the metenkephalin-induced prolactin secretion is modulated by the gonadal steroid environment.

Animals↗
PubMed1991

In vivo and in vitro evidence of growth hormone-releasing factor-like produced locally in the adenohypophyseal cells of the rat.

In order to characterize immunocytochemically the existence of GRF in the rat adenohypophysis and the origin of this hormone, an immunocytochemical and morphometric study was made of r-GRF-immunoreactive cells from the adenohypophysis of untreated adult rats, adult rats treated intraventricularly with colchicine and in primary cultures of adult rat adenohypophyseal cells that had been incubated with serum devoid of GRF. r-GRF immunoreactive cells were observed in untreated rat pituitaries, both male and female, although the numbers of positive cells were greater in the males (p less than 0.05) and were found to increase in number following treatment with colchicine (p less than 0.01). These cells appeared dispersed throughout the anterior lobe, without forming clusters, and were often close to blood vessels. Additionally, immunoreactive cells appeared in the cultures at 7 days of incubation. The presence of GRF-immunoreactive cells in the adenohypophysis of rats previously treated with colchicine suggests the existence of a non-hypothalamic origin for r-GRF; this is confirmed by the findings obtained in the in vitro studies which would corroborate the hypothesis that the origin of the neuropeptide is in the rat adenohypophysis itself.

Animals↗
PubMed1991

Sexually dependent changes in rat somatotropic cells following bilateral adrenalectomy.

In order to elucidate the existence of gender-related variations in both growth hormone (GH) release and the activity of somatotropic cells following bilateral adrenalectomy, a morphometric analysis was performed on GH-immunoreactive cells from adult male and female rats after bilateral adrenalectomy, correlating the findings with the serum levels of the hormone. The results obtained were compared to those found in untreated animals. Bilateral adrenalectomy was seen to induce a decrease in serum GH levels (p less than 0.01) in male rats; this was accompanied by a significant decrease in cellular area (p less than 0.01), cytoplasmic area (p less than 0.05) and nuclear area (p less than 0.01) and by a decrease in the cytoplasmic immunoreaction intensity of GH cells. By contrast, the above-mentioned changes did not appear in the female rats. These results suggest that the action of glucocorticoids on the synthesis and release of GH depends on the sex of the animal.

Adrenalectomy↗
PubMed1991

Morphometric study of the LH-immunoreactive gonadotrophic cells of rats following treatment with methoclopramide.

The LH-immunoreactive cells of the adult rat hypophysis were studied morphometrically after chronic treatment with methoclopramide. The morphological features of these cells showed modifications in both male and female rats, after treatment. Additionally, morphometric changes revealed a significant decrease (p less than 0.05) in both cytoplasmic area, which was more evident in the female rats, and nuclear area, with respect to the normal and control animals. These findings suggest that chronic inhibition of the dopaminergic system in rats atrophies LH-immunoreactive gonadotrophic cells of rats.

Animals↗
PubMed1991

A comparative analysis of the vasotocin and vasopressin systems in the chicken and rat hypothalamus. An immunocytochemical study.

By means of the peroxidase-antiperoxidase technique a comparative immunocytochemical study of the distribution of the vasotocin- and vasopressin-reacting system in the chicken and rat hypothalamus was carried out. In both species it is possible to distinguish, on the basis of their topographical location, three different comparable populations: The first one is situated very close to the pial surface and the optic chiasma (L1 and L2 groups in the chicken and the supraoptic nucleus in the rat). The second one is located near to the third ventricle and corresponds to the suprachiasmatic nucleus of both species and the periventricular groups of the chicken (P1, P2, and P3 groups) and the periventricular subdivision of the paraventricular nucleus of the rat. The third one is situated between the two previous populations and consists of small clusters of reacting neurons (L3 and L5 groups in the chicken and the nucleus circularis and fornicalis in the rat) and to a large cluster of reacting neurons (L4 group in the chicken and the magnocellular part of the paraventricular nucleus in rat). In the median eminence of the chicken the immunoreactive axons were located in the internal zone and the anterior part of the external zone. However in the rat, the reaction was exclusively located in the internal zone.

Animals↗
PubMed1990

Morphological and functional study of the GH-immunoreactive adenohypophyseal cells in ovariectomized rats.

In view of the existence of a different secretion pattern of growth hormone (GH) between male and female rats, the aim of the present study was to analyse the role played by ovarian steroid hormones in the modulation of such secretion. To do so, postpubertal female rats were ovariectomized and killed at 30 days after the operation. The basal serum levels of growth hormone together with cell area, cytoplasmic area and nuclear area of the hypophyseal somatotropic cells of normal and ovariectomized rats were compared. The results obtained show that ovariectomy induces a significant decrease (p less than 0.05) in the basal serum levels of GH, accompanied by an increase in cellular and cytoplasmic areas, with no significant differences in nuclear area. Ovariectomy was also accompanied by an increase in reaction intensity and the number of GH-immunoreactive cells (p less than 0.01). These findings point to the shift towards a masculine secretory and morphological pattern following ovariectomy and supports the hypothesis that ovarian steroids intervene in the establishment of a different pattern in females compared to males.

Animals↗
PubMed1990

Morphometric changes of specific located vasopressin-reacting parvicellular neurons in the paraventricular nucleus of the rat after adrenalectomy.

The morphological-morphometric consequences of bilateral adrenalectomy on vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus were analyzed. Bilateral adrenalectomy led to a dramatic increase in the cellular area as well as the number of immunoreactive cells (when compared to those obtained in normal colchicine-treated animals) in the neurons located in the anterior, medial and periventricular parvicellular subdivisions of the paraventricular nucleus. By contrast, no changes were observed in either the dorsal or lateral parvicellular subdivisions or in any of the magnocellular subdivisions of the paraventricular nucleus.

Adrenalectomy↗
PubMed1990

Morphometric study of immunoreactive GH-cells of the adenohypophysis of rats treated with Met-enkephalin.

Morphological and morphometric changes were found in adenohypophyseal GH immunoreactive cells after intraventricular administration of Met-enkephalin to adult rats of both sexes. Morphologically, following Met-enkephalin treatment, the males showed cells stained intensely and homogeneously in their cytoplasm, while the females showed cells with a weaker degree of staining and a cytoplasm with a granular aspect; previous administration of naloxone prevented the changes observed in the males and intensified the reaction in the females. Morphometrically, in all the groups of animals studied, the males showed a greater cellular area than the females, accompanied by a decrease in the cytoplasmic area but without significant differences in the nuclear area. Met-enkephalin in both sexes produced an increase in cellular area, accompanied by a significant increase in the cytoplasmic area and, although less manifest, in the nuclear area. Neither kind of change appeared when naloxone was administered prior to Met-enkephalin treatment.

Animals↗
PubMed1990

Bisoprolol vs. chlorthalidone: a randomized, double-blind, comparative study in arterial hypertension.

The antihypertensive effect and tolerance of bisoprolol and chlorthalidone were evaluated in a randomized, double-blind, controlled trial during 4 weeks of treatment. A total of46 patients, aged 18-65 years, were initially included; 41 patients presenting with a diastolic blood pressure between 95 and 120 mm Hg at the end of a previous placebo period completed the trial. They were randomly allocated to two groups: 22 patients were treated with bisoprolol 10 mg o.d., and 19 patients with chlorthalidone 50 mg o.d. Both treatments induced a significant reduction in systolic and diastolic blood pressure (p < 0.001). No difference in antihypertensive efficacy was found between the two treatments after 4 weeks. However, with chlorthalidone, significant changes were found with regard to serum potassium (decrease; p < 0.001) and uric acid (increase: p < 0.05) and the incidence of clinical side effects was higher in the chlorthalidone group (37%) in comparison to the patients treated with bisoprolol (13%).

Adrenergic beta-Antagonists↗
PubMed1990

Bisoprolol and nifedipine SR in the treatment of hypertension in the elderly.

Forty outpatients (11 men and 29 women) aged between 65 and 85 years (mean age of 68 years) with mild to moderate hypertension [mean systolic/diastolic blood pressure (SBP/DBP) after 2 weeks on placebo of 175/102 mm Hg] were included in a randomized, double-blind, parallel-group study to compare the efficacy and tolerance of 10 mg of bisoprolol once daily (o.d., n = 20) and 20 mg of nifedipine sustained release (SR) b.i.d. (n = 20) during 4 weeks of treatment. SBP and DBP were significantly reduced compared to baseline with both treatments. There was no significant difference in efficacy between the two treatments after 2 and 4 weeks. After 2 weeks, the number of patients with normalized DBP (< or =90 mm Hg) was higher with bisoprolol than with nifedipine, this difference no longer being present after 4 weeks. Resting heart rate was significantly reduced with bisoprolol from 78+/-8 to 68+/-9 beats/min after 4 weeks, but there was no change in heart rate with nifedipine. Adverse events were reported by 6 patients on bisoprolol (20 events) and 12 patients on nifedipine (51 events) and the overall tolerance of bisoprolol was considered to be significantly better than that of nifedipine. Because bisoprolol is equally effective when administered once daily in comparison with nifedipine SR, which has to be given twice daily, and since bisoprolol exhibits a better tolerance, this beta-blocker appears to be a useful drug of first choice for the treatment of elderly hypertensive patients.

Adrenergic beta-Antagonists↗
PubMed1989

Morphofunctional study of mammotropic cells following intraventricular administration of met-enkephalin.

An ultrastructural and morphometric study was carried out on the adenohypophyseal mammotropic cells of rats treated intraventricularly with an acute dose (150 micrograms) of Met-enkephalin. In the female rats, clear features of cellular hyperactivity appeared after opioid administration. The changes affected the Golgi complex, the rough endoplasmic reticulum, the mature and immature secretory granules and the images of exocytosis. Such changes did not appear when naloxone was administered before the opioid, and naloxone induced an increase in the numerical density of lysosomal dense bodies with lipoid inclusions. In the male animals, administration of an identical dose of Met-enkephalin caused only a few significant changes, similar to those observed in the controls. It is concluded that Met-enkephalin administered intraventricularly causes evident modifications in the mammotropic cells of female rats whereas such changes in the male animals are not significant.

Animals↗
PubMed1989

Study of h-TSH immunoreactive adenohypophyseal cells following treatment with methymazole.

The TSH-producing adenohypohyseal cells of Wistar rats were studied after treatment with orally administered methymazole by the PAP immunocytochemical method. These cells were compared with those of normal animals. The effects of methymazole were different in the females to those observed in males. In both sexes, the numerical density (number of TSH cells per 1000 microns 2) increased after treatment. The cellular and cytoplasmic areas increased in the females while they decreased in the males. The nuclear area and the nuclear area/cytoplasmic area ratio increased in the males and decreased in the females following treatment with methymazole. This treatment caused the appearance of large, intensely stained cells, with an eccentric nucleus and cytoplasmic processes accompanied by weakly stained cells that were situated close to blood vessels.

Animals↗
PubMed1989

Three dimensional study of the rat urinary bladder in states of contraction and distension.

A qualitative and quantitative study of the apical surface of the superficial cells of the rat urinary bladder was made when the bladder was in states of contraction and distension. The study was performed with the scanning electron microscope. Qualitatively, no significant changes were observed with respect to the regional cell topography analyzed (fundus, body and neck of bladder) and only a progressive disappearance of folds and grooves with a more pronounced flattening of the poligonal luminal cell surface was apparent as distension increased. The quantitative data found point to significant differences between the cell populations analyzed, in particular the hexagonal cells, both at regional level and with respect to the state of contraction-distension of the urinary bladder. Isolated immature cells can be seen occupying the area left by desquamated cells that have different shapes, sizes and morphological characteristics to the mature cells.

Animals↗
PubMed1988

Annular gap junctions in cuboidal ependymocytes of the median eminence of the rat after intraventricular administration of methysergide and thyrotropin releasing hormone.

The annular gap junctions in the cuboidal ependymocytes of the median eminence of rats were studied after intraventricular administration (3rd ventricle) of methysergide and thyrotropin releasing hormone. Isolated annular gap junctions were found in the ependymocytes of normal animals. In experimental rats an increase was observed in the number of annular gap junctions at 5 min after administration of the drugs; the increase was more apparent at 10 min postadministration. Likewise, the ependymocytes showed a clear development of the Golgi complex and an increase in the number of vesicles close to the lateral membranes. Accordingly, the increase observed in annular gap junctions could be interpreted as a sign of cellular activity indicative of a greater exchange of substances through the ependymocytes.

Animals↗
PubMed1988

Ultrastructure of the surface of the organum vasculosum laminae terminalis in different animal species.

A scanning electron microscope study was made of the surface of the organum vasculosum laminae terminalis of the rat, dog and cat. The ependyma of this organ, in all three species, is lacking in cilia or is only monociliate; it exhibits numerous supraependymal processes and cell bodies and in the different species studied there are differences that affect the number, size and distribution of the supraependymal cells. There is a great richness of vessels in the supraepedymal layer of the organum vasculosum laminae terminalis.

Animals↗
PubMed1987

Morphology of the neural lobe of the hypophysis in rats treated with furosemide. I. Neurosecretory axons.

The changes found in the neurosecretory axons of the neural lobe of the hypophysis were studied in rats treated with furosemide for three days: over the whole period of treatment, the animals, according to each group, were deprived or not of water. In the animals with free access to water the axons contained neurosecretory granules with scarce content and low electron density; only some of them had vacuoles and autophagic bodies. In the animals deprived of water axon morphology was variable and axons showing vacuoles and autophagic bodies were abundant, as well as those presenting lamellar and dense bodies and also those in which filaments prevailed. The most outstanding modifications in this last group of animals were related to the dehydration and were not found in those animals which were given access to water again and which were in consequence rehydrated.

Animals↗