摘要:

The purpose of this study was to downregulate the transcriptiona message of arginine vasopressin (AVP) by antisense treatment. A complete phosphorothioate antisense oligodesoxynucleotide corresponding to the beginning of the coding region of rat AVP mRNA was constructed and injected into the lateral ventricle of rats. Within 3–6 h animals exhibited a temporary diabetes insipidus, which lasted up to 9 h. Accordingly, vasopressin immunoreactivity in the hypothalamic nuclei was reduced. Our results demonstrate that a specific and reversible inhibition of neuropeptide expression can be accomplished in the intact hypothalamo‐neurohypophysial system by antisense treatment, thus providing a novel tool for studies on stimulus‐secretion coupling in

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00561.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The role of cyclic 3′,5′‐guanosine monophosphate (cGMP) as a second messenger in LHRH neurons is not well understood. Recent studies involving nitric oxide, a direct activator of soluble guanylate cyclase (GC), have implicated cGMP in the regulation of LHRH secretion bothin vivoandin vitro. Evidence for the membrane‐bound form of GC in LHRH neurons has thus far not been reported. In polymerase chain reaction screening of various cell lines for the natriuretic peptide receptors—which represent GCs—we identified both GC‐A and GC‐B cDNAs by southern blot hybridization in reverse transcribed and amplified extracts of the GT1‐7 cell line, an immortalized LHRH neuronal cell line. Subsequent experiments demonstrated that all of the natriuretic peptides elevated cGMP production with a rank order of potency: CNP>ANP>BNP. Time course studies revealed a rapid intracellular accumulation of cGMP following exposure to CNP with a peak at 2.5 min. CNP was some 200‐fold more potent than the NO donor, sodium nitroprusside, in stimulating cGMP accumulation in these cells. These data show for the first time the presence of functional mGCs on LHRH cells, and suggest that the natriuretic peptides may also participate in the regulati

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00562.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Recent studies on experimental animals showed that long term activation of the hypothalamo‐pituitary‐adrenal axis is associated with increased vasopressin (AVP) colocalization in paraventricular corticotropin‐releasing hormone (CRH) neurons. In the present study we estimated the fraction of CRH neurons in which AVP is colocalized by double label immunocytochemistry in hypothalami of 10 control subjects of 21 ‐91 years of age and 10 age‐matched Alzheimer patients. CRH neurons in the paraventricular nucleus (PVN) of Alzheimer patients and control subjects showed similar age dependent increases in AVP colocalization. Based on this parameter, it seems that CRH neurons of Alzheimer patients are not overactivated as compared to age‐matched controls, but e.g. changes in m‐RNA for CRH should still b

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00563.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractMany neurons within the ventrolateral hypothalamus in guinea pigs contain estrogen‐induced progestin receptors as well as substance P. Retrograde tracing combined with immunocytochemistry was used to determine the specific projections of this subset of steroid‐ sensitive cells. Unilateral Fluoro‐Gold injections into the dorsal midbrain, including the central gray, labeled a large proportion of the ventrolateral hypothalamic neurons immunoreactive for both progestin receptors and substance P (approximately 30%); substantially fewer of these neurons were labeled by unilateral Fluoro‐Gold injections into the preoptic area (approximately 6%), medial amygdala (approximately 10%), or the bed nucleus of the stria terminalis (approximately 11 %). The projections of progestin receptor‐immunoreactive neurons in the ventrolateral hypothalamus were similar to those of progestin receptor/substance P double‐labeled neurons, while a slightly lower percentage of the ventrolateral hypothalamic, substance P‐immunoreactive neurons tended to project to each of these areas. These pathways may prove to be components of the neural circuitry underlying a variety of functions influenced by gonadal steroid hormones and substance P, such as female sexual behavior, salt intake, nociception a

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00564.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractHypothalamic tuberoinfundibular prolactin‐inhibiting neurons show decreased levels and synthesis of dopamine in two types of genetically prolactin‐deficient dwarf mice (Snell, Ames) which arise from separate mutations. A reduction to 2% of normal in this neuronal population has been quantified for Snell dwarfs. The present study was undertaken in order to quantify morphometrically the deficit and its distribution in Ames dwarf mice, including comparisons of sex and adult age. The brains of dwarf (df/df) and normal phenotypic (DF/?) sibling mice of both sexes from 4 to 16 months of age were immunostained for tyrosine hydroxylase, the rate‐limiting enzyme in dopamine synthesis; neuronal perikarya were counted in coronal sections of tuberoinfundibular arcuate nucleus (area A12), medial zona incerta (A13) and anterior periventricular (A14) hypothalamic areas at 180 μm rostral‐to‐caudal intervals. Normal (DF/?) mice exhibited no differences in neuron numbers, with regard to age or sex, in any of the three dopaminergic areas. In dwarf mice, a tendency toward decreased neuron numbers with age was statistically significant for area A14 only, and the size of the neuronal population in A12 was reduced in males compared with females. Total A12 neuron number in dwarfs was 48% of that in normal mice (P<0.001). Periventricular (A14) perikaryal numbers were reduced slightly (P<0.05) in dwarfs compared with normals. Numbers of A13 neurons were comparable for DF/? and df/df. The morphometric distribution of tyrosine hydroxylase‐immunoreactive neurons in A12 showed that the decrease in neuronal number in dwarfs was distributed throughout the rostral‐to‐caudal length of the nucleus, with significant decrease of total perikarya (P<0.05) at each 180 μm sampling interval. Thus, lifelong absence of prolactin in Ames dwarf mice is accompanied by a significant decrease in hypothalamic tyrosine hydroxylase‐immunoreactive neurons, which is restricted to hypophysiotropic areas, uniformly distributed within A12, and is less severe than the reduction in the phenotypically

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00565.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe complete sequence of the cDNA encoding the neuropeptide Y (NPY) Y1‐receptor has recently been deduced from a rat brain library, and the presence of messenger ribonucleic acid (mRNA) encoding Y1‐receptor protein has been demonstrated within the brain. Using quantitativein situhybridization histochemistry, the content and distribution of Y1receptor and preproNPY mRNAs have been investigated in the hypothalamic arcuate nucleus of adrenalectomized rats receiving glucocorticoid replacement therapy for 12 days by means of either high doses of dexamethasone in their drinking water or by subcutaneous corticosterone pellets. Basal metabolic parameters such as weight gain or loss, blood glucose and plasma insulin were monitored: Dexamethasone treatment induced weight loss and a state of hyperinsulinemia with normoglycemia, while corticosterone treated animals displayed metabolic parameters identical to sham ADX animals. Within the arcuate nucleus of glucocorticoid treated animals, levels of Y1receptor and preproNPY mRNAs were increased. In contrast, adrenalectomy itself had no effect upon Y1‐receptor mRNA levels or preproNPY mRNA levels in the arcuate nucleus. These studies demonstrate that glucocorticoids exert a stimulatory action on levels of Y1‐receptor mRNA and preproNPY mRNA levels in the hypothalamic arcuate nucleus. This is the first evidence to suggest that the expression of a neuropeptide‐receptor gene in the central nervous system may be directly sensitive to peripheral hormona

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00566.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractCorticotrophin‐releasing factor (CRF) and arginine vasopressin (AVP) are the primary neuropeptides regulating the secretion of ACTH from the anterior pituitary gland during fetal and adult life. However, a number of other neuropeptides including neuropeptide‐Y (NPY) appear to modulate the activity of this system. The potential role of NPY in the regulation of pituitary‐adrenal function was examined in fetal and adult sheep. Administration of NPY (6.5 μg) as a bolus injection into the third cerebral ventricle of adult ewes elicited a significant (P<0.05) increase in plasma concentrations of ACTH. In fetal sheep at day 125 gestation (term = 145 days) a five‐fold higher dose (30 μg) of NPY injected into the lateral cerebral ventricles also caused a significant increase in plasma concentrations of ACTH. The potential of NPY to influence ACTH secretion directly from the pituitary gland was investigated using primary cultures of fetal (day 130 gestation) and adult pituitary cells. CRF (10−10–10−7M) caused a significant (P<0.01) dose‐related increase in ACTH secretion from both fetal and adult pituitary cells. Furthermore, the secretion of ACTH from adult cells was significantly greater (P<0.05) than that from fetal cells. NPY (10−10–10−7M) had no effect on basal or CRF‐stimulated ACTH secretion from fetal or adult pituitary cells. Pre‐incubation of pituitary cells with cortisol (10−9and 10−7M) for three days significantly inhibited CRF‐stimulated ACTH secretion but had no effect on basal ACTH release. The simultaneous addition of NPY did not alter the ability of cortisol to inhibit CRF‐stimulated ACTH secretion.These data show that exogenous administraiton of NPY stimulates pituitary‐adrenal activity in fetal and adult sheep. The lack of any direct pituitary effects of NPY suggests that this neuropeptide acts centrally within the brain to exert its

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00567.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractLocalization of GnRH‐immunoreactive neuronal system was studied by immunohistochemistry in the nasal‐brain area of the crested newt,Triturus carnifex. Besides adults, developmental stages were those from hatchlings up to complete metamorphosis. Neurons containing immunoreactive GnRH were first detected in the nasal area of larvae with yet undifferentiated gonads. Subsequently, in prometamorphic stages, GnRH‐immunoreactive cell bodies and fibers were detected in the proximal part of the terminal nerve as well as along the ventromedial surface of the olfactory bulbs. In older larvae with sexually differentiated gonads and up to the metamorphic climax GnRH‐neurons were detected, as a rostral to caudal continuum, along the ventromedial surface of the olfactory bulbs and midtelencephalon. This is exactly the route followed by the terminal nerve. In the adult brain, besides the presence of occasional GnRH‐neurons and fibers in the terminal nerve proximal to olfactory bulbs, olfactory bulbs and the mid‐basal telencephalon, another aggregate of immunoreactive neurons was present in the anterior preoptic area, and a greater number of fibers in the habenular area as well as in the infundibular floor, median eminence and pars nervosa. These data suggest the nasal area to forebrain migration (along the course of the terminal nerve) of GnRH‐neurons during development in the

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00568.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractLaser scanning confocal microscopy was used to analyse changes in free cytosolic calcium ([Ca2+]i) in Xenopus laevis oocytes expressing the cloned rat TRH receptor in response to TRH. In oocytes expressing TRH receptors, TRH invariably evoked a dose‐dependent, biphasic calcium response. This response consisted of an initial transient planar wave of calcium propagating just below the surface of the membrane followed by a slower, secondary calcium phase. The TRH antagonist, chlordiazepoxide, markedly inhibited this calcium wave. The origins of calcium involved in this biphasic response were investigated using a variety of intra‐ and extra‐cellular calcium antagonists. The intracellular calcium antagonists thapsigargin and TMB‐8 reduced the initial and to a lesser extent the secondary phase of the planar calcium wave. In contrast, EGTA and the calcium channel blocker nifedipine produced a profound inhibition of the secondary phase while the initial phase was only slightly reduced. These results indicate that the release of intracellular calcium is predominantly responsible for the initial phase of the calcium wave while the influx of extracellular calcium is mainly involved in the secondary phase. Qualitative changes in the patterns of calcium release induced by TRH were observed following pretreatment with intracellular calcium antagonists. Following pretreatment with these compounds, TRH induced spiral or regenerative calcium waves. Addition of EGTA to the extracellular medium did not alter these responses confirming the importance of intracellular calcium in the generation of these spiral calcium waves. This study demonstrates the nature and multiplicity of regulating mechanisms of [Ca2+]ifollowing activation of TRH receptors expressed in Xenopus

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00569.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractInterleukin‐1 (IL‐1) and interleukin‐6 (IL‐6) have been reported to stimulate the release of corticotrophin‐releasing hormone (CRN)in vitro, the response being antagonized by the cyclo‐oxygenase inhibitor, indomethacin. The effects of cytokines on the other major ACTH‐releasing hormone, vasopressin (AVP), and the other neurohypophysial hormone, oxytocin, have been little studied, and the published data are conflicting. We have therefore used a previously validated rat hypothalamic expiant model to evaluate whether IL‐1β and IL‐6 can directly activate the AVP and oxytocin neurosecretory system. In addition, we have also investigated the effects of inhibition of cyclo‐oxygenase (CO) and lipoxygenase (LO) activities on the stimulated release of AVP and oxytocin by means of a series of antagonists, including a specific LO pathway inhibitor. The static rat hypothalamic incubation system used involves fresh hypothalamic expiants with consecutive 20‐min incubations, and estimation of AVP and oxytocin concentrations in the medium by specific and sensitive radioimmuno‐assays. It was found that IL‐1β produced a dose‐dependent increase in the release of AVP and oxytocin at doses of 10 and 100 U/ml (P<0.005). Only at the higher dose of 100 U/ml was IL‐6 able to increase significantly AVP and oxytocin release (P<0.05). These stimulatory effects of IL‐1β and IL‐6 were blocked by cyclo‐oxygenase inhibitors, indomethacin (28 μM) and ibuprofen (100 nM), but not by the lipooxygenase inhibitor, BW A4C (10 μg/ml), suggesting that prostaglandins are involved in this process. Thus, cytokines are clearly able to modulate the neurohypophysial systemin vitro, the effects probably be

ISSN:0953-8194    

DOI:10.1111/j.1365-2826.1994.tb00570.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY