Browsing by Subject "Hypophysis"

Now showing 1 - 5 of 5
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    Architecture of the mammalian pituitary cholinergic system with observations on a putative blood acetylcholine sensor
    (Murcia : F. Hernández, 1996) Caffé, A. R.
    Acetylcholine ( ACh) play s an important role in pituitary gland function. Little is known, however, about the source and trajectory of pituitary ACh, the location of pituitary cholinergic receptors. and the pathways along which the release of pituitary ACh is controlled. Therefore choline acetyltransferase (ChAT) immunoreactive profiles have been investigated in the rat median eminence and pituitary. Furthermore, both muscarinic- (mAChRp-L) and nicotinic receptor proteinlike (nAChRp-L) immunoreactivity have been examined in the rat, rabbit, and cat pituitary. The results have demonstrated that the rat pituitary ChAT network is composed of neurons in the hypothalamic arcuate nucleus and a great number of terminals in the median eminence. In the pituitary, ChAT immunolabeled profiles were virtually absent. This suggests that much of the ACh acting on pituitary cells is released as a humoral factor from the median eminence. Al1 the examined animals expressed mAChRp-L immunostained endocrine cells in the intermediate lobe. Apart from this, marked species differences in AChRp-L immunolabeled profiles have been found. In addition, strong mAChRp-L immunoreactive rod to cone-shaped bodies were detected associated with blood vessels of the anterior and intermediate lobes in the rat and rabbit, but not in the cat. The immunolabeling was present in particles on the body plasma membrane. These characteristics suggest that the function of these structures might be to sense pituitary blood ACh levels. Consequently the name hlood acetylcholine reading hodies (BARBs) was adopted to indicate these stmctures. It is proposed that the BARBs may play a role in the feedback control of ACh release from the median eminence.
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    Effect of hypertension and captopril treatment on the vasopressin in the rat median eminence and posterior lobe of the hypophysis. An immunohistochemical study
    (Murcia : F. Hernández, 1999) Castañeyra Perdomo, A.; Pérez Delgado, M.M.; Carmona-Calero, E.; Pérez-González, H.; Marrero-Gordillo, N.; Ferres Torres, R.
    The present study analyses the effects of hypertension andlor its oral treatment with captopril (angiotensine-converting enzyme inhibitor) on the rat median eminence (ME) and the posterior lobe of the hypophysis (PL). After an immunohistochemical reaction using an antibody against arginine-vasopressin, we compared by densitometry the amount of vasopressin immunoreactive material (vasopressin-ir) of these centers in 4 groups of animals: control Wistar Kyoto rats (WKY), spontaneously hypertensive rats (SHR), WKY rats treated with captopril (WKY-T) and SHR rats also treated with the same drug (SHR-T). Captopril was administrated at a dosage of 0.1 mglml in. the drinking water from the 8th to the 15th weeks. We have found that the rats showing the lowest level of vasopressin-ir, in both ME and PL, were those from the SHR group, the concentration increasing after oral captopril treatment (SHR-T), although without reaching the values of WKY rats. Then, ACE inhibition by captopril influences vasopressin content in brain areas where the hormone is concentrated before being released, which supports the hypothesis that suggests a central modulatory effect of ACE inhibitors, contributing to their therapeutic action on hypertension.
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    Effect of hypertension on the angiotensin II fibres arriving at the posterior lobe of the hypophysis of the rat. An immunohistochemical study
    (Murcia : F. Hernández, 2000) Pérez Delgado, M.M.; Carmona-Calero, E.; Marrero-Gordillo, N.; Pérez-González, H.; Castañeyra Perdomo, A.
    We studied immunohistochemically the posterior lobe of the hypophysis (PL) of 15-week-old spontaneously hypertensive rats (SHR) and of matched normotensive Wistar Kyoto rats (WKY), by using our own polyclonal antibody raised in mice against Angiotensin I1 (mouse-antiangiotensin 11, MAAII). The blood pressure, water intake and volume of the PL were also recorded. The SHR rats were hypertensive, drank more water and showed a clear hypertrophy of their hypophysial PL. Also the PL of the SHR animals showed an increase in the immunoreactivity to the antiangiotensin I1 antibody in the fibres arriving at the PL, with respect to the PL of WKY rats. This increase is compatible with the hyperactivity of the brain RAS, depletion of vasopressin content in the PL and increase in plasmatic levels of vasopressin described in SHR rats with respect to normotensive animals, as angiotensin I1 could locally stimulate vasopressin release to plasma from the neurohypophysis.
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    Morhometric changes in GH-immunoreactive adenohypophyseal cells induced by intraventricular administration of colchicine to adult rats
    (Murcia : F. Hernández, 1992) Carretero, J.; Sánchez, F.; Rubio, M.; Juanes, J.A.; Blanco, E.; González, R.; Riesco, J. M.; Vázquez, R.
    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 leve1 on the release of somatostatin and, indirectly, on the intracellular pool of GH and hormonal secretion.
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    Morphometric study of the LH-immunoreactive gonadotrophic cells of rats following treatment with methoclopramide
    (Murcia : F. Hernández, 1991) Carretero, J.; Sánchez, F.; Montero, M.; González, R.; Blanco, E.; Riesco, J. M.; Vázquez, R.
    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 < 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.