间断性低压性缺氧对大鼠下丘脑NOS和生长抑素神经元的影响

本研究采用 NADPH-d组化与生长抑素免疫组化技术探讨了间断性低氧 (每天 6h) 1d、7d、15 d、2 1d和 3 0 d对大鼠下丘脑内一氧化氮合酶 (NOS)和生长抑素的影响。结果表明 :间断性低压性低氧可使下丘脑室旁核、视上核 NOS和室周核生长抑素阳性神经元数量明显增多 ,且低氧第 1d即达高峰 ,7和 15 d维持较高水平 ,2 1d开始下降 ,3 0 d则明显减少。NOS阻滞剂 L-NAME(3 0 mg/kg,ip)明显抑制低氧诱导下丘脑生长抑素阳性神经元数的增多。以上结果说明 ,下丘脑内源性的 NO与生长抑素参与了间断性低压性缺氧反应 ,并与慢性缺氧的适应反应有关 ;此外 ,NO作为下丘脑内源性的神经递质对下丘脑生长抑素的释放有促进作用     

The estrogen receptor (ER) alpha, but not ER beta, gene is expressed in hypothalamic growth hormone-releasing hormone neurons of the adult female rat

Growth hormone (GH) synthesis and release from pituitary somatotropes is controlled by the opposing actions of the hypothalamic neuropeptides, GH-releasing hormone (GHRH) in the arcuate nucleus (ARC), and somatostatin in the periventricular nucleus (PeV) and ARC. There is a striking sex difference in the pattern of GH secretion in rats. We have previously demonstrated in male rats that 70% of GHRH neurons in the ARC contain the estrogen receptor alpha (ER alpha) gene, whereas less than 5% of somatostatin neurons in the ARC and PeV expressed the ER alpha or ER beta gene. In addition, it has been reported that the PeV somatostatin neurons of neither sex possess ER immunoreactivity. However, there is no available data about colocalization of ERs and GHRH and/or somatostatin in the ARC of female rats. In this study, we used in situ hybridization in the adult female rat brain to determine whether GHRH neurons and/or somatostatin neurons in the ARC coexpress the ER alpha or ER beta gene. In the ARC, ER alpha mRNA was seen in the ventrolateral region where GHRH mRNA signals were also observed, and in the dorsomedial region where somatostatin mRNA signals were also observed. From studies using adjacent sections through these areas, the distribution of these cells appeared to overlap in part with that of cells containing ER alpha mRNA. On the other hand, few positive cells for ER beta mRNA were observed in the ARC. The double-label in situ hybridization studies showed that in the ARC, 73.4% of GHRH neurons contain ER alpha mRNA, whereas less than 5% of somatostatin neurons express the ER alpha gene. These results indicated that the majority of the GHRH neurons in ARC have ER alpha, but not ER beta, and few somatostatin neurons in ARC have ER alpha or ER beta in either adult female or male rats, suggesting that colocalization with ERs in GHRH and/or somatostatin neurons is not an important determinant of the gender specific pattern of GH secretion.     

大鼠下丘脑内的一氧化氮合酶与雌激素受体双标神经元

目的:探讨一氧化氮合酶(NOS)和雌激素受体(ER)在下丘脑诸核团的分布及共存,为揭示雌激素与一氧化氮之间的内在联系提供形态学依据。方法:采用NADPH-d组织化学法并结合免疫组织化学技术,观察雌性大鼠下丘脑内NOS阳性神经元、ER阳性神经元以及NOS/ER双染神经元的形态及分布。结果:NOS阳性神经元主要分布在下丘脑室旁核、视上核、下丘脑外侧区和室周核;ER阳性神经元在下丘脑诸核团的表达不及NOS阳性神经元广泛;NOS与ER双染神经元主要分布在下丘脑的室旁核、视上核、下丘脑外侧区及室周核;其他区域可见散在分布的双染神经元。结论:NOS与ER双染神经元主要集中分布在视上核的背内侧和背外侧部及室旁核小细胞部腹内侧区,在下丘脑外侧区分布较广但比较分散,室周核呈散在分布。     

精氨酸加压素阳性神经元在大鼠下丘脑的定位

目的:观察大鼠精氨酸加压素(AVP)及其mRNA阳性神经元在下丘脑的分布和形态特征。方法:以尼氏染色作参照,运用免疫组化和原位杂交观察AVP及其mRNA在下丘脑的表达。结果:下丘脑AVP及其mRNA阳性的神经元由吻侧到尾侧依次出现于视上核,视上核和视交叉上核,视上核、视交叉上核和室旁核,视上核和室旁核及视上核、下丘脑前核和室旁核。AVP及其mRNA阳性神经元仅占据视上核背内侧;在第三脑室室管膜膜内或膜下可见AVP阳性神经元的胞体或突起;在不同核团内AVP阳性神经元的形态存在差异。结论:AVP及其mRNA阳性神经元在下丘脑不同核团内具有特异性分布;AVP阳性触液神经元可能是调节脑脊液和脑组织之间AVP含量的桥梁。     

束缚应激大鼠下丘脑内一氧化氮合酶与c-fos蛋白的共存

为了探讨下丘脑内一氧化氮与应激之间的关系，本实验应用NADPH-d组化法和C-fos免疫组化技术相结合的方法，对束缚应激大鼠下丘脑内一氧化氮合酶（NOS）和c-fos蛋白的分布以及两者的共存关系进行了观察。结果表明，大鼠在束缚应激4h后，（1）室旁核大细胞部和视上核可见密集深染的NOS阳性大细胞；（2）室旁核小细胞部、背内侧核、穹窿周核、环状核、腹内侧核腹外侧部、结节内侧核、外侧区、室周区、乳头体前核和内侧核的外侧区等核团出现疏密不等和深浅不一的NOS阳性细胞；（3）C-fos蛋白以室旁核表达最为强烈，视前区、背内侧核、弓状核和外侧区亦有较强的表达；（4）在外侧区、室旁核小细胞部及其附近的室周区、背内侧核及乳头体前核腹侧部约有10％～15％的中、小型NOS阳性细胞同时表达C-fos蛋白，室旁核大细胞部则仅有较少的NOS阳性大细胞表达C－fos蛋白，在结节区、结节内侧核和视上核视交叉后部则偶见双标细胞。结果提示上述下丘脑核团内的部分一氧化氮能神经元与束缚应激反应有关。     

雄性大鼠下丘脑雄激素受体蛋白及其mRNA表达的探讨

为了观察雄激素受体 ( AR)蛋白及其 m RNA在大鼠下丘脑的表达 ,本研究采用免疫组织化学和原位杂交方法观察了成年 ( 3月龄 )雄性大鼠下丘脑 AR阳性神经元的存在及其表达。结果显示 ,雄激素受体阳性神经元广泛分布于下丘脑诸核 ,尤其是弓状核、腹内侧核、背内侧核、室周核、室旁核 ,阳性神经元多为小细胞。同时在基因水平证实部分下丘脑神经元能合成 AR,提示雄激素可能作用于以上区域。     

大鼠下丘脑向嗅球的传出纤维联系──WGA－HRP和HRP法研究

采用ＷＧＡ－ＨＲＰ和ＨＲＰ逆行追踪法，对２０只ＳＤ大鼠下丘脑向嗅球的投射进行了观察。在同侧下丘脑视前大细胞核均观察到较多的酶标记细胞；同侧下丘脑外侧核和室周核常出现少量酶标记细胞；偶见同侧下丘前核、乳头体外侧核、下丘脑腹内侧核前部、背内侧核腹侧部及弓状核出现少量酶标记细胞。     

睫状神经营养因子对应激大鼠下丘脑、垂体精氨酸加压素含量的影响

目的：研究睫状神经营养因子（ＣＮＴＦ）对应激大鼠下丘脑、垂体精氨酸加压素（ＡＶＰ）含量及下丘脑ＡＶＰ阳性神经元的影响。方法：选用条件性足底电击应激大鼠模型，用放射免疫分析的方法观察双侧海马微量注射ＣＮＴＦ对应激大 下丘脑及垂体ＡＶＰ含量的影响，用免疫组织化学染色的方法结合光镜与图像分析观察下丘脑室旁核ＡＶＰ阳性神经元的变化。结果：应激大鼠下丘脑、垂体ＡＶＰ含量升高；下丘脑室旁核ＡＶＰ阳性神经元增多，染色变深，平均吸光度显著增加。给予ＣＮＴＦ的大鼠下丘脑、垂体ＡＶＰ含量明显降低；下丘脑室旁核ＡＶＰ阳性神经元减少，染色变浅，平均吸光度明显减少。结论：ＣＮＴＦ明显降低应激引起的下丘脑、垂体ＡＶＰ含量的升高。     

Leptin长型受体与生长抑素共存于猪前脑内

目的：研究三元杂交猪和梅山猪仔猪前脑内Leptin长型受体(Ob-Rb)mRNA与生长抑素(SS)免疫反应阳性物质的共存关系。方法：用原位杂交与免疫组织化学相结合的方法。结果：Leptin长型受体mRNA和生长抑素免疫反应阳性神经元分布于下丘脑室周核、背内侧核、腹内侧核、室旁核、海马杏仁核及大脑皮质。上述结构内一些表达Leptin长型受体mRNA的神经元也含有生长抑素免疫反应阳性物质。结论：两种猪前脑内Ob-Rb mRNA与SS免疫反应阳性物质的共存情况无明显差异。Leptin可直接作用于下丘脑的生长抑素免疫反应阳性神经元调节动物的能量代谢生长和繁殖等活动。     

Melanopsin expression in dopamine-melatonin neurons of the premammillary nucleus of the hypothalamus and seasonal reproduction in birds

Melanopsin (OPN4) is a photoreceptive molecule regulating circadian systems in mammals. Previous studies from our laboratory have shown that co-localized dopamine-melatonin (DA-MEL) neurons in the hypothalamic premammillary nucleus (PMM) are putatively photosensitive and exhibit circadian rhythms in DAergic and MELergic activities. This study investigates turkey OPN4x (tOPN4x) mRNA distribution in the hypothalamus and brainstem, and characterizes its expression in PMM DA-MEL neurons, using in situ hybridization (ISH), immunocytochemistry (ICC), double-label ISH/ICC, and real time-PCR. The mRNA encoding tOPN4x was found in anatomically discrete areas in or near the hypothalamus and the brainstem, including nucleus preopticus medialis (POM), nucleus septalis lateralis (SL), PMM and the pineal gland. Double ICC, using tyrosine hydroxylase (TH, the rate limiting enzyme in DA synthesis)—and OPN4x antibodies, confirmed the existence of OPN4x protein in DA-MEL neurons. Also, tOPN4x mRNA expression was verified with double ISH/ICC using tOPN4x mRNA and TH immunoreactivity. PMM and pineal gland tOPN4x mRNA expression levels were diurnally high during the night and low during the day. A light pulse provided to short day photosensitive hens during the photosensitive phase at night significantly down-regulated tOPN4x expression. The expression level of tOPN4x mRNA in PMM DA-MEL neurons of photorefractory hens was significantly lower as compared with that of short or long day photosensitive hens. The results implicate tOPN4x in hypothalamic PMM DA-MEL neurons as an important component of the photoreceptive system regulating reproductive activity in temperate zone birds.     

Effects of repeated cold stress on activity of hypothalamic neurons in rats during performance of operant licking task

The present study investigated the effects of repeated cold stress on single neuron activity in the lateral hypothalamic area (LHA) and medial hypothalamic area (MHA) of behaving rats. The rats were trained to lick a protruding spout in response to one of several cue-tone stimuli (CTSs) to ingest water, or amino acid, NaCl or glucose solution. Following this training, the rats were raised under either stressed (repeated temperature changes between -3 and 24 degrees C) or control (24 degrees C) condition for 2 mo. During this period, neuronal activity was recorded in the LHA and MHA. For rats raised under the stressed condition, mean spontaneous firing rate of LHA neurons was significantly greater than for rats under the control condition. More LHA neurons in the stressed rats responded, with an accompanying decrease in activity (inhibitory response), to CTSs than in the control rats. During extinction learning, some LHA neurons enhanced or reversed the responses to CTSs in the stressed rats, whereas no LHA neurons showed such response changes in the control rats. In contrast to the effects of the stressed condition on LHA neuron activity, mean spontaneous firing rate of MHA neurons in the stressed rats was significantly smaller than in the control rats. Fewer MHA neurons in the stressed rats responded to CTSs and/or ingestion of sapid solutions. The preceding results suggested that repeated cold stress produces a specific pattern of changes in spontaneous activity and responses to sensory stimuli in LHA and MHA neurons; this could underlie the behavioral changes induced by repeated cold stress such as hyperphagia and hyper-reactivity to sensory stimuli.     

脊髓伤对断面上方脊髓及下丘脑生长抑素神经元的影响

用免疫组化光镜、电镜方法,观察脊髓半横断18天后大鼠的脊髓和下丘脑SS神经元的分布状况。主要结果:(1)脊髓损伤侧断面上方的背角I～Ⅲ板层,呈色较淡,其SS阳性反应既弱于健侧,也弱于对照鼠两侧相应区域的反应。(2)下丘脑SS阳性细胞增多,在室周核尤为显著(P<0.05);(3)电镜观察显示:断面上背角SS阳性细胞内阳性颗粒甚少,偶见变性胞体及纤维,室周核SS神经元阳性物则较多,细胞器也较丰富。著者认为:断面上方背角区的变化主要与SS上行传导纤维离断,而其远端SS量减少有关,室周核SS神经元的增多,则可能为代偿性的负反馈之结果。     

心理应激对大鼠下丘脑室周核生长抑素mRNA神经元的影响

目的：探讨心理应激因素对下丘脑室周核生长抑素ｍＲＮＡ阳性神经元的影响。材料和方法：采用心理应激大鼠模型，以原位杂交组织化学及图像分析技术，检测下丘脑室周核生长抑素ｍＲＮＡ阳性神经元的表达程度和神经元体积密度及单位体积细胞数密度的变化。     

Effects of morphine on hypothalamic corticotropin-releasing factor (CRF), norepinephrine and dopamine in non-stressed and stressed rats

The effects of morphine on the hypothalamic corticotropin-releasing factor (CRF), norepinephrine (NE) and dopamine (DA) concentrations were investigated in non-stressed and stressed rats. Acutely administered morphine stimulated both the synthesis and release of CRF in the hypothalamus, thereby activating the pituitary-adrenocortical system in non-stressed rats, but inhibited the stress-induced CRF synthesis and ACTH-corticosterone secretion. Either a morphine or ether-laparotomy stress reduced NE and DA concentrations in the hypothalamus. A pretreatment with morphine inhibited the stress-induced reduction in the hypothalamic NE and DA concentrations, and induced a significant increase in the DA concentration. These observations suggest that hypothalamic NE and DA are involved in morphine-induced changes in hypothalamo-pituitary-adrenocortical (HPA) activity and that endogenous opiates have a role in regulating CRF secretion by interacting with hypothalamic biogenic amines.     

Chronic intermittent hypoxia modulates nNOS mRNA and protein expression in the rat hypothalamus

Exposure to chronic intermittent hypoxia (CIH) as observed in obstructive sleep apnea (OSA) elicits a sustained elevation of sympathetic activity and arterial blood pressure. Our overall hypothesis is that intermittent hypoxia might increase sympathetic activity, in part by altering neuronal nitric oxide synthase (nNOS) expression in the hypothalamus, where nitric oxide is sympathoinhibitory. In this study, we begin investigation of this hypothesis by testing the more specific hypothesis that the CIH alters nNOS expression in regions of the hypothalamus associated with cardiovascular regulation. To test the effect of CIH on NOS expression we subjected male Sprague-Dawley rats to cyclic intermittent hypoxia for 8h/day, for 35 days. Experimental rats showed an increase in systemic blood pressure. In situ hybridization and immunohistochemistry were performed on hypothalamic sections, respectively. The CIH rats displayed significantly lower levels of both nNOS mRNA and protein in the paraventricular hypothalamic nucleus (PVN) with different changes in the subareas of the PVN. There was a decreased level of nNOS mRNA and protein in the subfornical organ and the periventricular hypothalamic nucleus of the CIH rats, but no significant change in the supraoptic nucleus or the lateral hypothalamic area. This work suggests that examination of central regulation of sympathetic activity may help elucidate the mechanisms of hypertension after CIH.     

Effects of iontophoretically applied cortisol on tuberoinfundibular neurons in hypothalamic paraventricular nucleus of anesthetized rats

Effects of cortisol on 22 tuberoinfundibular (TI) neurons in the paraventricular nucleus (PVN) of the hypothalamus were examined in urethane-anesthetized rats. Iontophoretically applied cortisol excited 10 (45%) of 22 TI-neurons tested, whereas the cortisol inhibited 4 (31%) of 13 neurons in the periventricular hypothalamic nucleus. Intravenously applied cortisol (0.5 mg in 0.5 ml saline) excited 4 (36%) of 11 TI neurons tested and inhibited 1 (9%). These results suggest that cortisol may have an excitatory effect on TI neurons in the PVN.     

Chronic food restriction differentially affects NPY mRNA level in neurons of the hypothalamus and in neurons that innervate liver

Neuropeptide Y (NPY) is found in neurons of the brain and in the neurons that innervate abdominal organs including liver. Major biological function of hypothalamic NPY is regulation of appetite and body weight homeostasis. In the periphery, biological function of NPY varies, depending on the organ/tissue. Increased hypothalamic NPY mRNA level in response to chronic caloric restriction is a well documented phenomenon. The effect of food restriction on NPY mRNA level in neurons that innervate liver has not been published so far. To evaluate how chronic food restriction affects liver (and other abdominal organs) NPY mRNA level, we compared NPY mRNA abundance in liver, kidney cortex, perirenal white adipose tissue and in hypothalamus of rats maintained on chronic restricted diet. Data presented in this paper indicate that chronic food restriction: (a) caused the increase of NPY mRNA level in the hypothalamus, (b) caused the decrease of NPY mRNA level in the liver, and (c) was without effect on NPY mRNA level in kidney cortex and perirenal white adipose tissues. Moreover, rats maintained on restricted diet displayed lower serum NPY, leptin and insulin concentrations and higher serum corticosterone concentration. Together, these data suggest that hypothalamus and liver (and other abdominal organs) NPY gene expression is differentially regulated by caloric restriction. It seems that liver NPY gene expression in contrast to the hypothalamus NPY gene expression is not suppressed by leptin.     

Direct hypothalamic innervation of the trigeminal motor nucleus: a retrograde tracer study

It is currently thought that the hypothalamus influences motor output through connections with premotor structures which in turn project to motor nuclei. However, hypocretinergic/orexinergic projections to different motor pools have recently been demonstrated. The present study was undertaken to examine whether hypocretinergic/orexinergic neurons are the only source of projections from the hypothalamus to the trigeminal motor nucleus in the guinea-pig. Cholera toxin subunit b was injected into the trigeminal motor nucleus in order to retrogradely label premotor neurons. Two anatomically separated populations of labeled neurons were observed in the hypothalamus: one group was distributed along the dorsal zone of the lateral hypothalamic area, the lateral portion of the dorsomedial hypothalamic nucleus and the perifornical nucleus; the other was located within the periventricular portion of the dorsomedial hypothalamic nucleus. Numerous cholera toxin subunit b+ neurons in both populations displayed glutamate-like immunoreactivity. In addition, premotor neurons containing hypocretin/orexin were distributed throughout the lateral dorsomedial hypothalamic nucleus, perifornical nucleus and lateral hypothalamic area. Other premotor neurons were immunostained for melanin concentrating hormone; these cells, which were located within the lateral hypothalamic area and the perifornical nucleus, were intermingled with glutamatergic and hypocretinergic/orexinergic neurons. Nitrergic premotor neurons were located only in the periventricular zone of the dorsomedial hypothalamic nucleus. None of the hypothalamic premotor neurons were GABAergic, cholinergic or monoaminergic. The existence of diverse neurotransmitter systems projecting from the hypothalamus to the trigeminal motor pool indicates that this diencephalic structure may influence the numerous functions that are subserved by the trigeminal motor system.     

大鼠下丘脑大细胞分泌系统内一氧化氮合酶与催产素的共存

目的　为进一步阐明一氧化氮 (NO)与催产素 (OT)在下丘脑神经内分泌调节中的作用提供形态学资料。方法　用NADPH d组织化学方法 ,并结合免疫组织化学相结合技术 ,观察大鼠下丘脑大细胞分泌系统内一氧化氮合酶 (NOS)与OT免疫阳性神经元的分布与共存关系。结果　NOS与OT在下丘脑室旁核、视上核等下丘脑各大神经分泌核区内的分布基本类似 ,并呈部分共存关系。并且初次在第三脑室室周区内观察到NOS/OT双重反应阳性触液神经元。结论　研究结果提示NO与OT在有关下丘脑生殖与性行为的神经内分泌调节活动中起着重要的介质作用。