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The aim of the study was to find the direct effects of a possible correlation between different glutamate concentrations (5, 50 and 200 µM) on the one hand and catecholamine release from rabbit hypothalamus homogenate during a 90 min incubation on the other hand. Brain structures were obtained from 12 decapitated female rabbits that were 12 weeks old. After decapitation the obtained brain of the animal was placed in 0.9% NaCl. Next, each brain structure from each rabbit (approx. 50 mg) was placed in incubation wells (cell culture Sigma) containing 1 ml of incubation medium (Krebs phosphate buffer containing glucose 0.3% bovine serum albumin and 0.1% BSA) without (control) or with three doses of Glu in a concentration of the following: I – 5 μM, II – 50 μM, and III – 200 μM. Every 30 minutes each slice of tissue of each brain structure was placed in the next hole with the medium. The medium collected after 30, 60 and 90 minutes of the experiment was used for dopamine, noradrenaline and adrenaline RIA measurement. The obtained results show that Glu has a direct influence on catecholamines release from the hypothalamus as a central brain structure of the HPA axis in stress inducing and adaptive processes. Generally, there was an inhibitory effect on catecholamine release from the hypothalamus homogenates. Our findings show that Glu has great influence on the brain’s motivational structure, which may indicate its contribution to stress response by modulating the amount of catecholamine released.
Human food and animal feed may contain phytoestrogens. These plant compounds possess a chemical structure and biological activity similar to animal estrogens. With regard to the important role of estrogens in males, it is necessary to extend knowledge pertaining to the influence of phytoestrogens on the male reproductive tract. These chemicals may affect the hypothalamic-pituitary-testis axis, controlling functions of the reproductive tract. The results showed in this review indicate that, especially in high doses, the phytoestrogens alter functions of hypothalamus, pituitary gland and testis. These effects depend on species, kind and treatment level of phytoestrogens, length of exposure as well as on the means of administration.
The aim of the study was the immunohistochemical evaluation of the impact of the age of animals treated with the sodium salt of glutamic acid on the behaviour of astrocytes of the infundibular nucleus (IN). Immunohistochemical peroxidase-antiperoxidase reactions were conducted on brain sections of 10-day-old (I) and 63-day-old (II) rats treated s.c with monosodium glutamate (MSG) in a dose of 4 g/kg b.w. for three consecutive days. The staining was performed using specific antibodies against glial fibrillary acidic protein (GFAP), S-100β protein and Ki-67 antigen. Cells immunopositive for the proteins under investigation were assessed morphologically and morphometrically in an Olympus BX51 light microscope with the Cell ^ D program. Statistically significant differences were tested using ANOVA and the non-parametric Kruskal-Wallis test. In the infundibular nucleus of 10-day-old rats treated with MSG, there was an increase in the number of GFAP, S-100β and Ki-67 immunopositive astrocytes without any changes in their morphology, which was typical of immature glia. In adult rats treated with MSG, a decrease in the number of cells expressing GFAP and S-100β was found. Most astrocytes had thick and weakly branched processes, in contrast to those observed in control animals. The results of our study showed a diverse behaviour of astroglia of IN in young and adult rats treated with MSG. In 10-day-old rats, hyperplasia of glia occurred, whereas in 63-day-old individuals there was a loss and hypertrophy of astrocytes, which may indicate a late stage of their reactivity. This information may contribute to targeting the therapy of diseases of the nervous system induced by the excitotoxic effects of glutamate.
Rats of Wistar strain at different inbred level: 0, 25, 37, 50 and 100% have been exposed to stress of 3 day starvation and 3h swimming. The control group have been subjected to ether anaestesia in order to collect blood samples. The effect of inbred level on the function of hypothalamic-pituitary-corticoadrenal axis have been studied. Corticotropin /ACTH/ and corticosterone /C/ concentrations in blood serum of female and male rats have been determined by RIA. Histological analysis of hypothalamic secretory nucleus, responsible for corticotropin releasing factor /CRF/ production, as well as fascicular layer of adrenal cortex responsible for glucocorticoid production has been made. It has been found that the potency of the hormones examined decreases with the increase of inbred level. The results prove sexual dimorphism in the rosponse of general adaptation syndrome. Females are less sensitive not only to the effort of rising homozygosity but also to stress.
One of the most important inhibitory neurotransmitter in the control of gonadoliberin (GnRH) secretion is gamma-aminobutyric acid (GABA). To examine the role of GABAA receptor mediating systems in the control of GnRH/LH release from the preoptic area and ventromedial hypothalamus of ewes in different reproductive stages (seasonal anestrus, follicular and luteal phase of the estrous cycle) the extracellular concentration of GnRH, ß-endorphin, noradrenaline, dopamine and metabolites of catecholamines: MHPG, DOPAC were quantified during local stimulation or blockade of GABAA receptors with muscimol or bicuculline, respectively. Stimulation of GABAA receptors in the preoptic area and ventromedial hypothalamus markedly attenuatted GnRH/LH release in the anestrous ewes and in sheep during follicular phase of the estrous cycle but did not affect these hormones secretion in animals during the luteal phase of the estrous cycle. The activation of GABAA receptors in these structures in different way affected ß-endorphinergic and catecholaininergic system activity in anestrous ewes arid animals during the follicular phase; lack of changes in the release of ß-endorphin, noradrenaline and dopamine was noted in ewes during the luteal phase. With the exception of preoptic area in anestrous ewes the blockade of GABAA receptors in the preoptic and ventromedial hypothalamus affected in specifical way the activity of ß-endorphinergic and catecholaminergic systems in these structure in all animals. In conclusion: presented results indicate that activation of GABAA receptors in the preoptic area and ventromedial hypothalamus of anestrous ewes and sheep during follicular phase of the estrous cycle inhibits GnRH/LH secretion. Presented results indicate that different neural mechanisms may be involved in the suppression of GnRH/LH by GABA directly through the GABAA receptor mechanism on the perikaria or on the axon terminals of GnRH cells, and/or indirectly through GABAA receptor processes on ß-endorphinergic and catecholaminergic systems. Lack of changes in GnRH/LH release during GABAA receptor activation in ewes during luteal phase of the estrous cycle indicates that the influence of GABA on GnRH-ergic activity depends on physiological state of animals. Blockade of GABAA receptors in the anestrous and cycling ewes does not change GnRH/LH release; it is suggested that blockade of GABAA recreceptors may change GnRH neurons response to ß-endorphin and dopamine.
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