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  • 1
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The hypothalamic corticotropin-releasing hormone system and the sympathetic nervous system are anatomically and functionally interconnected and hormones of the hypothalamic-pituitary-adrenocortical axis contribute to the regulation of catecholaminergic systems. To investigate the role of glucocorticoids on activity of the adrenal gland, we analysed plasma and adrenal catecholamines, tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) mRNA expression in rats injected with metyrapone or dexamethasone. Metyrapone-treated rats had significantly lower epinephrine and higher norepinephrine production than control rats. Metyrapone increased TH protein synthesis and TH mRNA expression whereas its administration did not affect PNMT mRNA expression. Dexamethasone restored plasma and adrenal epinephrine concentrations and increased PNMT mRNA levels, which is consistent with an absolute requirement of glucocorticoids for PNMT expression. Adrenal denervation completely abolished the metyrapone-induced TH mRNA expression. Blockage of cholinergic neurotransmission by nicotinic or muscarinic receptor antagonists did not prevent the metyrapone-induced rise in TH mRNA. Finally, pituitary adenylate cyclase activating polypeptide (PACAP) adrenal content was not affected by metyrapone. These results provide evidence that metyrapone-induced corticosterone depletion elicits transsynaptic TH activation, implying noncholinergic neurotransmission. This may involve neuropeptides other than PACAP.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In humans, an altered control of cortisol secretion was reported in adult men born with a low birth weight making the hypothalamic-pituitary-adrenal (HPA) axis a possible primary target of early life programming. In rats, we have recently shown that maternal food restriction during late pregnancy induces both an intrauterine growth retardation and an overexposure of fetuses to maternal corticosterone, which disturb the development of the HPA axis in offspring. The first aim of this work was to investigate, in adult male rats, whether perinatal malnutrition has long-lasting effects on the HPA axis activity during both basal and stressful conditions. Moreover, as the HPA axis and sympathetic nervous system are both activated by stress, the second aim of this work was to investigate, in these rats, the adrenomedullary catecholaminergic system under basal and stressful conditions. This study was conducted on 4-month-old male rats malnourished during their perinatal life and on age-matched control animals. Under basal conditions, perinatal malnutrition reduced body weight and plasma corticosteroid-binding globulin (CBG) level but increased mineralocorticoid receptor (MR) gene expression in CA1 hippocampal area. After 30 min of restraint, perinatally malnourished (PM) rats showed increased plasma noradrenaline, adrenocorticotropin hormone (ACTH) and corticosterone concentrations similarly as controls, but calculated plasma-free corticosterone concentration was significantly higher and adrenaline level lower than controls. During the phase of recovery, PM rats showed a rapid return of plasma ACTH and corticosterone concentrations to baseline levels in comparison with controls. These data suggest that in PM rats, an elevation of basal concentrations of corticosterone, in face of reduced CBG and probably increased hippocampal MR lead to a much larger impact of corticosterone on target cells that mediate the negative-feedback mechanism on the activities of both the HPA axis and sympathoadrenal one.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    General and Comparative Endocrinology 34 (1978), S. 312-322 
    ISSN: 0016-6480
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2072
    Keywords: Key words ACTH ; Corticosterone ; GABA ; Noradrenaline ; Adrenaline ; Stress ; Rat ; Diazepam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Gabolysat PC60 is a fish protein hydrolysate with anxiolytic properties commonly used as a nutritional supplement. Objective: The diazepam-like effects of PC60 on stress responsiveness of the rat pituitary-adrenal system and on sympathoadrenal activity were studied. Methods: The activity of the pituitary-adrenal axis, measured by plasma levels of adrenocorticotropic hormone (ACTH) and corticosterone (B) of the sympathoadrenal complex, measured by circulating levels of noradrenaline (NA) and adrenaline (A), and the gamma aminobutyric acid (GABA) content in the hippocampus and the hypothalamus were investigated in male rats which received daily, by an intragastric feeding tube, for 5 days running either diazepam (1 mg/kg) or PC60 (300 or 1200 mg/kg). Controls received only solvent (carboxymethylcellulose 1%). Six hours after the last force-feeding, the rats were subjected to 3 min ether inhalation or 30 min restraint and killed by decapitation 30 min after ether stress or at the end of restraint. Results: Baseline plasma levels of ACTH, B, NA and A were not affected by either diazepam or PC60. Both ether- and restraint-induced release of ACTH, but not B, were similarly and drastically reduced by diazepam and PC60 (1200 mg/kg). Both diazepam and PC60 (1200 mg/kg) deleted restraint-induced NA and A increases. Both treatments also reduced the ether-induced rise of A. Basal levels of GABA were significantly increased in both the hippocampus and the hypothalamus in PC60-treated rats and only in the hippocampus in diazepam-treated ones. In controls, ether inhalation as well as restraint increased GABA content of these two brain structures. In contrast, such stress procedures performed in PC60-treated rats reduced GABA content slightly in the hippocampus but significantly in the hypothalamus. In diazepam-treated rats, GABA content of the hypothalamus was unaffected by stresses but that of the hippocampus was slightly decreased. Conclusions: Present data suggest diazepam-like effects of PC60 on stress responsiveness of the rat pituitary adrenal axis and the sympathoadrenal activity as well as GABA content of the hippocampus and the hypothalamus under resting and stress conditions. These effects of PC60 agree with anxiolytic properties of this nutritional supplement, previously reported in both rats and humans.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 169 (1976), S. 335-344 
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Rat foetus ; Cytoimmunology: MSH, ACTH ; Hypothalamus ; Cytodifferentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To investigate whether the hypothalamus is involved in the cytodifferentiation of the anterior pituitary gland, rat foetuses were encephalectomized in utero on day 16 of pregnancy. Pituitary sections from encephalectomized and normal littermate foetuses were studied on day 21 with the immunofluorescence technique using antibodies and α-MSH, anti β-MSH, anti α-(17–39) ACTH and anti β-(1–24) ACTH. On day 16, only the anti β-MSH revealed a few cells in the pars distalis but not in the pars intermedia. On the other hand, on day 21, the pituitary cells reacting with antibodies anti α-MSH, anti β-MSH and anti α-(17–39) ACTH were as numerous in the encephalectomized foetuses as in the normal littermate foetuses. The cells revealed with the antibody anti β-(1–24) ACTH were less numerous and less fluorescent in the pars distalis and intermedia of the hypophysis of the encephalectomized foetuses. On day 21, the adrenals of the encephalectomized foetuses were atrophied in comparison with those of the normal littermate foetuses but they were larger than on day 16. These data suggest that the cytodifferentiation of the corticotroph and melanotroph cells of the hypophysis occurs without the influence of the hypothalamus which is necessary for the normal release of ACTH.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Rat fetus ; Immunocytology ; Hypothalamus ; ACTH, MSH, LPH, GH, Prolactin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ontogenesis of cells containing polypeptide hormones (ACTH, MSH, LPH, GH and Prolactin) was investigated in the fetal rat hypophysis by immunohistochemistry using the peroxidase-antiperoxidase complex. Corticotrophs, melanotrophs and lipotropic cells were revealed earlier in the pars distalis than in the pars intermedia. In the pars distalis, cells producing LPH were found in the morning of day 15 of gestation using anti-γ- or anti-β-LPH sera, and in the afternoon using anti-α- or β-endorphin sera. Cells containing β-MSH were observed from the afternoon of day 15. The cells stainable with the anti-α-MSH, anti-β-(17-39)ACTH and anti-β-(l-24)ACTH sera appeared on day 16. In the pars intermedia, the cells producing α-MSH, β MSH, α- and β-endorphin, γ and β-LPH were observed in the morning of day 17, while cells containing ACTH were only revealed in the afternoon of the same day of gestation. Based on the treatment of serial paraffin sections with various antisera, it was clearly shown that MSH, ACTH, and LPH occur in the same cells located in the pars distalis as in the pars intermedia. The development of the corticotrophs, melanotrophs and lipotropic cells does not require the presence of the fetal hypothalamus or other central nervous structures. The pituitary glands of 21 day-old fetuses encephalectomized on day 16 showed as many reactive cells as those of the littermate controls. The somatotrophs were first revealed in the pars distalis in the afternoon of day 19. The cells producing prolactin were not observed before day 21 of gestation. On some cases GH and prolactin were found together in one cell. The cytodifferentiation of GH and prolactin cells is apparently not under hypothalamic control.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Foetal rat ; Cytoimmunology-MSH-ACTH ; Adrenals ; Corticosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pituitary sections from 15 to 21 day-old rat foetuses have been studied with the immunofluorescence technique, using antibodies anti α-MSH, anti β-MSH and anti β (1–24) ACTH. The first ACTH cells appear on day 17 of pregnancy in the pars distalis of the hypophysis and only on day 18 in the pars intermedia. β-MSH cells have been observed on day 16 in the pars anterior and on day 17 in the pars intermedia, while α-MSH cells appear only on day 18 and exclusively in the pars intermedia. The cytodifferentiation of the β-MSH and ACTH cells occurs in the pars intermedia with about a 24 hour delay in comparison to that of the pars distalis. The first revealed cells are always located in the posterior half of the pituitary gland. The corticostimulating activity of the hypophysis has been tested with the fluorescence intensity of the corticotrophs, the adrenal weight, the adrenal content in corticosterone and the plasma corticosterone level. The fluorescence of the corticotrophs increases on day 18, shows a maximum on day 19 and decreases until term. The adrenal weight rises regularly between day 16 to day 20, thereafter the increase subsides. Adrenal and plasma corticosterone concentrations reach a peak on day 19 of pregnancy. These data suggest that hypophyseal corticostimulating activity is very high between days 18 and 19 and decreases between days 19 and 21.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: Somatostatin Fetal rat ; Pancreas ; Duodenum ; Growth retardation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunohistochemistry was employed to study the development of somatostatin-containing cells in the pancreas and duodenum of rat fetuses and of 1–7 day-old newborns. Immunoreactive cells were first detected in the pancreatic islets on day 17 of gestation and in the duodenum on day 18. Somatostatin cells were numerous in the pancreas and gut at term and in early postnatal stages. The development of somatostatin-containing cells in both pancreatic islets and duodenum was not affected by either fetal hypophysectomy on day 16 or intrauterine growth retardation induced by ligature of the main uterine vessels on day 17 of gestation.
    Type of Medium: Electronic Resource
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