ISSN:0028-3835    

DOI:10.1159/000127157

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

NOR-1 is a novel member of the NGFI-B/RNR-1 subfamily within the nuclear receptor superfamily, and has been implicated in signal transduction mediated by various second messengers. To investigate the physiological role of NOR-1 we examined its gene expression in various adult rat tissues and developing rat brain by the quantitative reverse transcription-polymerase chain reaction using in vitro synthesized RNA as an internal standard. The NOR-1 gene was expressed in all tissues examined, but predominantly in the cerebral cortex and pituitary glands. Thymus, adrenal glands, spleen, epididymis, submandibular glands and deferent ducts showed moderate expression. In the brain, NOR-1 gene expression was developmentally regulated, with the peak levels on gestational day 18. These findings suggest a ubiquitous role of NOR-1 in signal transduction in diverse tissues. These findings also suggest that the nervous, endocrine and immune systems may be highly exposed to NOR-1-inducing stimuli under normal conditions in adult rats. Developing rat brain cells may most frequently receive the relevant signal on day 18 of gestation.

ISSN:0028-3835    

DOI:10.1159/000127158

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000127159

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Oxytocin receptors are regulated during parturition and lactation. Gonadal steroids are thought to be key players in this regulation. It is not well documented how oxytocin receptor gene expression is regulated in the CNS. In this study we analyzed potential estrogen effects on the oxytocin receptor mRNA levels in some areas integral to the limbic-hypothalamic system, namely the ventromedial nucleus of the hypothalamus (VMH), posterior medial nucleus of amygdala (MeAmyg), and arcuate nucleus (ARC), as well as the caudate putamen (CPu), CA1 region of the hippocampus, anterior pituitary, and uterine tissue of ovariectomized (OVX) female rats. By in situ hybridization we observed a 4.4-fold increase in oxytocin receptor mRNA levels in the VMH after 48 h of estrogen treatment when compared to OVX rats. Smaller increases were observed in the MeAmyg, hippocampus, and anterior pituitary (3.18, 1.76, and 2.55, respectively). No changes in oxytocin receptor mRNA levels were observed in the CPu or ARC after estrogen treatment. A similar finding resulted from slot-blot analysis of total mRNA extracts. In uterine tissue, 48 h of estrogen treatment increased oxytocin receptor mRNA level in the myometrium (3.13-fold). No changes in oxytocin receptor mRNA levels were observed after 12 and 24 h of estrogen treatment. These findings suggest that the estrogenic regulation of oxytocin receptor binding in both CNS and uterine tissues may in part be mediated by de novo synthesis of oxytocin receptor mRNA or by alterations in the stability of oxytocin receptor gene transcripts.

ISSN:0028-3835    

DOI:10.1159/000127160

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Staphylococcal enterotoxin B (SEB) is a bacterial superantigen which stimulates T cells bearing the Vβ8 motif on the T-cell receptor. This stimulation is MHC class II dependent, and in vivo results in a rapid and pronounced T-cell cytokine response. Based on previous evidence that SEB stimulates corticosterone production in BALB/c mice, which possess a high percentage of Vβ8+ T cells, we explored the effects of SEB on the hypothalamic-pituitary-adrenal (HPA) axis and identified the peripheral immunologic cellular requirements for these effects. Administration of SEB stimulates corticosterone in a dose-dependent manner, with peak production of corticosterone occurring by 2 h after intraperitoneal challenge with 50 µg SEB. Challenge with staphylococcal enterotoxin A, which activates Vβ3+ and Vβ11+ T cells (deleted during ontogenesis in BALB/c mice), did not increase ACTH or corticosterone production. Furthermore, SEB challenge increased plasma ACTH, which accounted for the increased plasma corticosterone, and increased the expression of c-fos in the PVN region of the hypothalamus. In vivo elimination of macrophages did not prevent the corticosterone response to SEB, suggesting that pituitary-adrenal activation does not require macrophages. However, when mice were pretreated with the T-cell immunosuppressant cyclosporin A, the significantly increased ACTH and corticosterone production in response to SEB was dramatically attenuated. These results demonstrate that bacterial superantigens can stimulate the HPA axis, and that functional T cells may play an obligatory role in this ef

ISSN:0028-3835    

DOI:10.1159/000127161

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The purpose of this study was to investigate whether the ovulatory cycle interferes with the effect of the acute-phase response of a systemic immune activation on the transcription of the immediate early gene c-fos and the stress-related neuropeptide corticotropin-releasing hormone (CRH) in the brains of female rats. Throughout the day of proestrus and diestrus-2 (09.00, 12.00, 15.00 h), adult rats received either a single intraperitoneal injection of the endotoxin lipopolysaccharide (LPS, 200 µg/100g body weight) or the vehicle solution and were killed 3 h later (12.00, 15.00, 18.00 h). Frozen brains were mounted on a microtome, cut in 30-µm slices and then processed for the detection of c-fos mRNA and CRH primary transcript (heteronuclear [hnRNA]) by means of in situ hybridization histochemistry using 35S-labeled exonic and intronic probes, respectively. LPS injection induced a profound expression of c-fos mRNA in the several nuclei and areas of the brain, such as the organum vasculosum of the lamina terminalis/medial preoptic area, supraoptic nucleus, parvo- and magnocellular divisions of the hypothalamic paraventricular nucleus (PVN), arcuate nucleus/median eminence, central nucleus of the amygdala, locus coeruleus, nucleus of the solitary tract, area postrema and ventrolateral medulla. Interestingly, the intensity of expression of c-fos mRNA depended on the phase of the estrous cycle and/or the time of the day. Indeed, in several of the structures described above, LPS induced a more pronounced c-fos signal in the morning of proestrus than the afternoon and diestrus-2. CRH primary transcript was significantly increased by LPS treatment selectively in the parvocellular division of the PVN and the highest hybridization signal was observed in the morning of proestrus, a period where a large number of c-fos-positive cells were colocalized in CRH-immunoreactive neurons. A significant increase in the levels of AVP hnRNA was also observed in the parvocellular PVN of animals sacrificed at noon and early afternoon of both pro- and diestrus days. These results provide evidence that the neuroendocrine events regulating the reproductive cyclicity influence the endotoxin-induced activation of the early gene c-fos in selective structures of the brain and the stimulation of neurons directly involved in the regulation of the HPA axis. It is possible that the gonadal status of female mammals plays a crucial role in the integration of the organism in the presence of foreign material in preventing an exaggerated immune response during particular phases of the ovulatory cycle. The capacity of female animals to modulate the intensity through which the neuronal circuitry activated during immunogenic processes is likely to be an elegant sexual dimorphism participating in the adjustment of the responses in line with the physiological deman

ISSN:0028-3835    

DOI:10.1159/000127162

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Folliculo-stellate cells (FS) represent a small percentage of anterior pituitary elements of still undetermined embryological origin. They are sparse among endocrine pituitary cells and are characterized by the lack of secretory granules and by the presence of few branching processes inserted between hormone-secreting cells. Although FS cell role is still under discussion, recent reports showed that they produce monocyte-derived cytokines able to influence the hormone production and modulate the immunoendocrine connections.In this study we applied three monocyte-macrophage markers (HAM56, KP1, HLA-DR) to 15 pituitary adenomas in order to ascertain whether FS cells belong to the macrophage lineage. In this case FS cells could be considered the resident macrophages of the pituitary. FS cells were identified according to the reactivity to S-100, GFAP and vimentin. We confirm that S-100 represents the most useful marker for these cells that were detected scattered between tumor cells in more than half of the adenomas. GFAP stained only a percentage of FS cells, while vimentin recognized in addition to stellate cells endothelia, perivascular and infiltrating macrophages. We were unable to detect the expression of the macrophage markers on S-100 and GFAP reactive cells. Indeed, HAM56, KP1 and HLA-DR-positive cells were mostly round, small size and located in the perivascular and septal positions where FS cells were never detected. Lack of expression of monocyte-macrophage lineage markers by FS cells in pituitary adenomas suggests their preferential neuroectodermal origin. However, further studies on normal human pituitary will be needed before ruling out a possible role for FS cells as resident pituitary macrophages.

ISSN:0028-3835    

DOI:10.1159/000127163

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

A number of recent studies suggest that interleukin 1β (IL-1β) is a major mediator of hypothalamo-pituitary-adrenal (HPA) responses following infectious aggression. We investigated whether IL-1β mediates long-term changes in HP A activity and studied the cellular regulation of the anterior pituitary. To mimic chronically elevated IL-1β production thought to occur during infectious diseases, osmotic pumps (Alzet type) were implanted in the peritoneal cavity of male rats and hIL-1β was infused continuously at rates of 1 or 3 µg/day. Effects of hIL-1β action on plasma ACTH, β-endorphin (β-EP) and corticosterone (CORT) secretion and on anterior pituitary (AP), ACTH and β-EP content were followed. In addition, hypothalamic (HT) CRH mRNA and in AP, CRH receptor (CRH-Rc) mRNA, POMC nuclear primary transcript RNA, POMC nuclear intermediate processing RNA and POMC nuclear and cytoplasmic mRNA were quantified using a highly sensitive solution hybridization nuclease protection assay. Continuous infusion of hIL-1 β stimulated the HPA axis at varying degrees. Increased HT CRH gene expression, AP POMC gene transcription, ACTH and β-EP release occurred only during the first 3 days of the treatment. A long-lasting enhancement of ACTH and β-EP synthesis and of POMC gene expression resulted from activated POMC gene transcription followed by an increased POMC mRNA stability and decreased POMC mRNA turnover. In the AP, stimulation of ACTH and β-EP secretion and POMC gene transcription disappeared after continuous IL-1β treatment, possibly in part due to a refractory process mediated by decreased CRH-Rc gene expression in

ISSN:0028-3835    

DOI:10.1159/000127164

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

It has been suggested that atrial natriuretic peptide (ANP) is the long-sought inhibitor of corticotropin (ACTH) secretion, but the evidence is conflicting. We have examined the effect of ANP and C-type natriuretic peptide (CNP) on the secretion of ACTH by perifused equine pituitary cells in an in vitro milieu intended to mimic the in vivo milieu in the horse. Corticotropin-releasing hormone (20 pM) and cortisol (0 or 100 nM) were perifused continuously and 7 pulses of arginine vasopressin (AVP; 10 nM) applied for 5 min at 30-min intervals. ANP (1 nM) or CNP (1 nM) were perifused continuously for 75 min, beginning before the 3rd AVP pulse. Neither ANP nor CNP, with or without cortisol, significantly altered the ACTH secretory response to the AVP pulses. We conclude that these natriuretic peptides are unlikely to act at the pituitary as rapid inhibitors of ACTH secretion in the horse.

ISSN:0028-3835    

DOI:10.1159/000127165

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

We studied the presence of the mineralocorticoid receptor (MCR) in the eye with the aid of a number of immunochemical techniques. Immunoblotting with a polyclonal antibody, directed against the rat renal MCR, revealed a single band of about 102 kD in extracts prepared from whole bovine or rat retina similar to that observed in cytosol from the kidney and myocardium from these species. Isolated cells of the bovine retinal pigment epithelium (RPE) similarly exhibited a 98- to 102-kD band in Western blots developed with the aid of anti-MCR antiserum. The 98- to 102-kD band was also obtained following autoradiography of RPE cytosol irradiated in the presence of 3H-R 5020. This fluorographic pattern was abolished when RU 26752, an antagonist specific to the MCR, was allowed to compete with radiolabelled promegestone. The MCR-3H-RU 26752 complex in RPE cytosol underwent heat activation, as judged by binding to DNA cellusose, and could also be precipitated by anti-MCR IgG. In primary cultures, the proliferation of the RPE cells was inhibited by the two MCR-specific antagonists RU 26752 and ZK 91587. The loss of the MCR-specific immunofluorescence in RPE cells after only 3 passages in culture was associated with refractoriness to the inhibitory effect of both of these spironolactones. Immunohistochemistry, using MCR-specific antiserum, revealed strong fluorescence in specific areas of the rat eye. In the retina, immunopositivity was observed in Müller cells, external and internal limiting membranes, the vitreous base lining and in the pigment epithelium. Epithelial cells of the ciliary body, iris and cornea also exhibited strong MCR-specific immunofluorescence. Thus, both the epithelial and the nonepithelial compartments of the ocular tissues form interesting new targets to delineate the mechanism of action of mineralotropic hormones

ISSN:0028-3835    

DOI:10.1159/000127166

出版商:S. Karger AG    

年代:1997

数据来源: Karger