加压素在自发性高血压大鼠与正常大鼠下丘脑视上核、室旁核神经元内表达

目的观察加压素(AVP)在自发性高血压大鼠(SHR)与正常大鼠下丘脑视上核(SON)、室旁核(PVN)内的分布。方法应用光镜和免疫细胞化学技术。结果SHR的AVP阳性细胞内分泌颗粒密集呈棕黄色,正常大鼠组则染色较浅。SHR大鼠SON内AVP阳性神经元百分数(69.30±18.10%)明显多于正常大鼠(59.53±16.97%,P<0.05),而两组大鼠PVN内AVP的表达无明显差异。结论AVP在下丘脑的血压调节活动中起着重要的介导作用,中枢AVP含量的异常增加可能与高血压的发病有关。     

针刺对金黄地鼠视交叉上核c-Fos表达的影响

目的观察针刺导引对金黄地鼠视交叉上核内c-Fos表达的影响。方法实验动物为雄性叙利亚金黄地鼠,共30只,随机分为电针组和捆绑对照组,每组15只。金黄地鼠经驯化后进入自由运行状态,在恒定黑暗第3天于近似昼夜时间(CT)9:00,15:00,21:00分别给予电针、捆绑刺激,每个时间点5只动物。各方法治疗2小时后用免疫组织化学方法检测各组金黄地鼠视交叉上核中c-Fos的免疫反应阳性细胞并对此进行计数,采用q检验方法进行统计学分析。结果30只金黄地鼠全部进入结果分析。针刺组与捆绑对照组比较在CT9:00和CT21:00可使视交叉上核内c-Fos表达显著增加(85.50±11.21,42.50±5.32,q=43.00,p<0.01;52.00±2.94,38.50±3.87,q=13.50,p<0.01)。结论针刺在CT9:00及CT21:00可使c-Fos表达增加,说明针刺对c-Fos表达的影响在主观白天及主观夜间的后半期。     

Hypothalamic osmoregulation is maintained across the wake–sleep cycle in the rat

In different species, rapid eye movement sleep (REMS) is characterized by a thermoregulatory impairment. It has been postulated that this impairment depends on a general insufficiency in the hypothalamic integration of autonomic function. This study aims to test this hypothesis by assessing the hypothalamic regulation of body fluid osmolality during the different wake–sleep states in the rat. Arginine‐vasopressin (AVP) plasma levels were determined following intracerebroventricular (ICV) infusions of artificial cerebrospinal fluid (aCSF), either isotonic or made hypertonic by the addition of NaCl at three different concentrations (125, 250 and 500 mm ). Animals were implanted with a cannula within a lateral cerebral ventricle for ICV infusions and with electrodes for the recording of the electroencephalogram. ICV infusions were made in different animals during Wake, REMS or non‐REM sleep (NREMS). The results show that ICV infusion of hypertonic aCSF during REMS induced an increase in AVP plasma levels that was not different from that observed during either Wake or NREMS. These results suggest that the thermoregulatory impairment that characterizes REMS does not depend on a general impairment in the hypothalamic control of body homeostasis.     

Ultrastructure of neurons in the hypothalamic suprachiasmatic nucleus of rats with different stress reactivity

The rats were divided into groups demonstrating extremely high and low stress reactivity depending on the results of testing for the nociceptive threshold and thermolability in response to bacterial lipopolysaccharide administration. Specific structural features of the nucleus and mitochondria were revealed in neurons of the hypothalamic suprachiasmatic nucleus in rats with constitutionally high reactivity, which reflects high functional activity and stress-induced lability of these structures. Ultramicroscopic study revealed phenotypic differences in one of the key hypothalamic nucleus, which enables potent and rapid neurogenic response of the stress system in animals with high stress reactivity. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 11, pp. 578–581, November, 2007     

Vasopressin release from rat medial basal hypothalamus in vitro after adrenalectomy or lesions of the paraventricular nuclei

Rat medial basal hypothalami (MBH) or neurointermediate lobes of the hypophysis (NIL) were superfused in vitro and stimulated electrically. The evoked release of vasopressin from the MBH was enhanced to 700% of controls when the tissue was taken from adrenalectomized rats. By contrast, the evoked release of vasopressin from the NIL was not changed after adrenalectomy. After bilateral lesions of the paraventricular nuclei, the evoked release of vasopressin from the MBH was reduced in subsequent in vitro experiments. The marked changes in vasopressin release occurred in spite of no or only small changes in the total tissue content of vasopressin. These data support the view that vasopressin may be released from the external layer of the median eminence into the hypophysial portal blood after activation of the hypothalamo-pituitary-adrenal axis.     

Effects of Electrical Stimulation of the Posterior Part of the Hypothalamus on the Spike Activity of Neurons in the Oral Nucleus of the Pons

Chronic experiments were performed on four cats to study evoked spike activity in neurons in the oral nucleus of the pons to electrical stimulation of the posterior hypothalamus in the waking, slow-wave sleep, and paradoxical sleep states. A total of 42% of study neurons were found to respond to stimulation during waking. PS-on and PS-off neurons were identified in the oral nucleus of the pons, along with phasic cells showing bursts of activity during the physical manifestations of paradoxical sleep. Stimulation induced inhibitory responses in PS-on neurons, excitatory responses in PS-off neurons, and excitatory and inhibitory responses in 68% and 32% respectively of phasic neurons. The magnitudes of evoked responses in these neurons changed during the sleep-waking cycle. These data demonstrate the involvement of the posterior hypothalamus in controlling the mechanisms of paradoxical sleep, these mechanisms being located in the oral nucleus of the pons.__________Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 90, No. 9, pp. 1094–1102, September, 2004.     

Vasopressin neuron survival in neonatal Brattleboro rats; critical factors in graft development and innervation of the host brain

Previously it was found that grafts of supraoptic plus paraventricular areas from 19-day-old foetal normal rats survived in the third ventricle of the brain of 4- to 6-day-old, vasopressin-deficient Brattleboro pups, but could not alleviate their polyuria. In the present series, factors important in graft development were analysed. Again using day-19 fetuses as donors, anterohypothalamus grafts as well as grafts placed near a crushed median eminence survived relatively poorly, but showed the presence of vasopressin neurons immunocytochemically one month post-grafting. Homotopic grafting in the supraoptic nucleus, however, even failed to show surviving vasopressin neurons. Graft survival was improved by the use of donor tissue of fetuses younger than day 19. Parvocellular vasopressin cells were frequently seen, organized into clusters resembling the normal suprachiasmatic nucleus. However, magnocellular neurons, as normally seen in supraoptic and paraventricular nuclei, only survived grafting when taken between days 11 and 15 of fetal age. It was concluded that only immature vasopressin neurons survived grafting under the condition employed. Magnocellular neurons had a limited fiber outgrowth into the host brain and median eminence. Most large neurons only stained with non-specific neurophysin antiserum, not with specific vasopressin-associated neurophysin antiserum. Thin fibers of the parvocellular vasopressin neurons provided only occasional and sparse innervation of the host median eminence and lateral septum (one case), but several examples of massive fiber bundles running dorsally from graft into host brain were observed. These fibers terminated in the thalamic periventricular area, a nucleus that is normally innervated by the vasopressin neurons of the suprachiasmatic nucleus.The failure of the grafts to provide adequate vasopressinergic innervation of the host median eminence probably explains why none of the nearly 200 Brattleboro neonates operated upon showed any sign of relief of their diabetes insipidus. It suggests, however, that the present procedures might be useful in restoring central vasopressinergic functions in the developing Brattleboro rat.     

大鼠下丘脑弓状核神经胶质细胞的年龄性变化

对青年、中年和老年大鼠下丘脑弓状核进行细胞计数和电镜观察显示;老年大鼠神经元数显著减少而神经胶质细胞数增加,胶质细胞与神经元呈卫星化状态增多,表面下复合器形成增加;星形胶质细胞、少突胶质细胞和小胶质细胞不同程度增生且部分发生异常改变:胞浆内脂褐素显著增加,体积增大,线粒体和粗面内质网变性和出现致密体等,胶质细胞突起伸长增多常包绕一些变性终未形成髓鞘样结构,上述结果表明;老年大鼠弓状核胶质细胞在数量、形态和结构上已发生增龄性变化,这可能是老年下丘脑神经内分泌功能紊乱的形态学基础之一.     

Arginine Vasopressin Fragment AVP4-9 Facilitates Induction of Long-Term Potentiation in the Hippocampus

Long-term potentiation of CA1 field potentials was induced by weak tetanic orthodromic stimulation of the Schaffer collateral/commissural fibers in isolated hippocampal slices perfused with a medium containing arginine vasopressin fragment AVP_4-9 in micromolar concentrations. It is hypothesized that AVP_4-9 affects induction of long-term potentiation at the intracellular level.     

The Effects of Serotonin on the Differentiation of Neurons Producing Vasoactive Intestinal Polypeptide in the Suprachiasmatic Nucleus of the Rat

The morphogenetic influences of serotonin on the differentiation of neurons synthesizing vasoactive intestinal polypeptide (VIP) in the suprachiasmatic nucleus were studied in rats. This was addressed by comparative morphofunctional analysis of VIP neurons in adult rats whose brains developed prenatally in conditions of normal and deficient serotonin metabolism. Serotonin deficiency was created in fetuses by treatment of their mothers with p-chlorophenylalanine (PCPA). Pregnant females in controls were treated with 0.9% NaCl. VIP neurons in experimental and control animals were found to show no differences in VIP mRNA concentrations and, probably, in the level of VIP synthesis. However, inhibition of serotonin synthesis led to an increase in the number of VIP-immunoreactive neurons and an increase in the VIP concentration within these cells. This was not associated with any change in neuron size, which was an indicator of the absence of functional hypertrophy accompanying activation of specific synthesis. Comparison of the data obtained here showed that during prenatal ontogenesis, serotonin has an imprinting influence on the differentiation of VIP neurons and is probably involved in the formation of the mechanism of VIP secretion.     

Dynamics of Neuron Spike Activity in the Oral Nucleus of the Pons During the Sleep-Waking Cycle in Cats

Chronic experiments on five cats were performed to study the spike activity of neurons in the oral nucleus of the pons during waking, slow-wave sleep, and paradoxical sleep. Groups of neurons with different dynamics of spike frequency were identified. Cells with rare discharges during waking and slow-wave sleep and maximum spike frequencies in the phasic stage of paradoxical sleep were regarded as PS-on neurons. Cells discharging at maximum frequency during waking, with decreases in frequency during slow-wave sleep and further decreases in paradoxical sleep, were regarded as PS-off neurons. Cells showing decreases in discharge frequency on the transition from waking to slow-wave sleep and increases in discharge frequency in paradoxical sleep, with grouped spikes during oculomotor activity, appeared to be responsible for generating the phasic phenomena of paradoxical sleep. The question of the involvement of neurons of different populations in the mechanisms of paradoxical sleep is discussed.     

Long-term facilitation of excitatory synaptic transmission in single motor cortical neurones of the cat produced by repetitive pairing of synaptic potentials and action potentials following intracellular stimulation

The effects of postsynaptic firing activity on excitatory postsynaptic potentials (EPSPs) were studied in the motor cortex of anaesthetized cats. Postsynaptic firing was induced by 1-5 nA cathodal current pulses via the recording intracellular microelectrode, while EPSPs were elicited by thalamic, callosal, pyramidal tract and somatosensory stimuli. In 102 cells, EPSP-spike stimulus pairs were applied with 0.2-1/sec frequency and 10-100 msec interstimulus intervals. In 42 neurones, reversible facilitation of paired EPSPs appeared lasting from 4 to 47 min. The synaptic facilitation in most cases was accompanied by membrane depolarization and an increase in input resistance. The effectiveness of current induced action potentials upon test EPSPs provided evidence for the postsynaptic localization of plastic changes occurring in conditioning experiments.     

Distribution of Gephyrin‐Immunoreactivity in the Trigeminal Motor Nucleus: An Immunohistochemical Study in Rats

It has been established that a postsynaptic scaffolding protein, gephyrin, is essential for anchoring two main groups of inhibitory receptors, GABA_A receptors (GABA_ARs) and glycine receptors (GlyRs), to the postsynaptic sites of neurons. The present study was primarily attempted to examine if expression patterns of gephyrin might be different between jaw‐closing (JC) and jaw‐opening (JO) motoneurons. The JC‐ and JO‐motoneurons in the rat trigeminal motor nucleus (Vm) were located in the dorsolateral (Vm.dl) and ventromedial (Vm.vm) divisions, respectively (Mizuno et al., 1975 ). Thus, immunoreactivity (IR) for gephyrin was investigated in the Vm: immunofluorescence histochemistry for gephyrin was combined with retrograde tract‐tracing of fluorogold (FG), which was injected into nerves innervating JC‐muscles or nerves innervating JO‐muscles; neuronal cells were counterstained with propidium iodide (PI). The Vm.dl was discriminated from the Vm.vm by the presence of vesicular glutamate transporter 1 (VGLUT1)‐immunopositive axon terminals, which were distributed in the Vm.dl but not in the Vm.vm (Pang et al., J Comp Neurol 2009 ;512:595–612). Gephyrin‐IR showed a punctate pattern of fluorescence, and motoneuronal profiles were coated with small clusters of gephyrin‐immunopositive puncta throughout the Vm. The distribution density of such clusters was apparently higher in the Vm.dl than in the Vm.vm; this was confirmed quantitatively by a method similar to that described by Lorenzo et al. (Eur J Neurosci 2006 ;23:3161–3170). On the basis of the present results, possible correlation between the distribution density of gephyrin clusters in the submembrane region of Vm motoneurons and that of axon terminals making inhibitory synapses on Vm motoneurons was discussed. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

The effects of oxytocin on the activity of cells in the anterior hypothalamus in experimental stress

Acute experiments on white laboratory rats were performed to study spike activity in neurons of the anterior hypothalamus in response to i.v. injections of different doses of oxytocin. The results showed that oxytocin evoked different types of rearrangement of neuron activity both in intact and in stressed animals. The dose-related effects of oxytocin affected the latent periods of neuron responses and the nature of rearrangements in spike activity. The greater the frequency of the baseline activity of the cells, the less marked was the response of the neurons to administration of oxytocin.Translated from Problemy Éndokrinologii, Vol. 50, No. 4, pp. 39–41, July–August, 2004.     

Changes in the Metabolic Activity of Neurons in the Anterior Hypothalamic Nuclei in Rats during Hyperthermia,Fever, and Hypothermia

Histochemical methods were used to detect differently directed changes in the metabolic activity of neurons in the anterior hypothalamic nuclei in rats during hyperthermia, fever, and hypothermia. Hyperthermia induced by high temperatures was associated with increases in the activities of enzymes involved in energy metabolism, with increases in RNA contents in neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus of the rat, which is evidence for increases in metabolic activity in the neurons of these nuclei. Endotoxin-induced fever was accompanied by decreases in the metabolic activity of neurons in the median preoptic nucleus, while activity in neurons of the supraoptic and paraventricular nuclei showed no significant change. The development of hypothermia induced by low temperatures was characterized by decreases in the metabolic activity of neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus. It is suggested that the differently directed changes in metabolic activity in the neurons of the anterior hypothalamus in hyperthermia, fever, and hypothermia are associated with their roles in the central mechanisms of thermoregulation (median preoptic nucleus) and neurosecretory processes (supraoptic and paraventricular nuclei).     

The Injection of Hypocretin-1 into the Nucleus Pontis Oralis Induces either Active Sleep or Wakefulness Depending on the Behavioral State when it is Administered

Study Objectives:

We previously reported that the microinjection of hypocretin (orexin) into the nucleus pontis oralis (NPO) induces a behavioral state that is comparable to naturally occurring active (rapid eye movement) sleep. However, other laboratories have found that wakefulness occurs following injections of hypocretin into the NPO. The present study tested the hypothesis that the discrepancy in behavioral state responses to hypocretin injections is due to the fact that hypocretin was not administered during the same states of sleep or wakefulness.

Design:

Adult cats were implanted with electrodes to record sleep and waking states. Hypocretin-1 (0.25 μL, 500mM) was microinjected into the NPO while the animals were awake or in quiet (non-rapid eye movement) sleep.

Measurements and Results:

When hyprocretin-1 was microinjected into the NPO during quiet sleep, active sleep occurred with a short latency. In addition, there was a significant increase in the time spent in active sleep and in the number of episodes of this state. On the other hand, the injection of hyprocretin-1 during wakefulness resulted not only in a significant increase in wakefulness, but also in a decrease in the percentage and frequency of episodes of active sleep.

Conclusions:

The present data demonstrate that the behavioral state of the animal dictates whether active sleep or wakefulness is induced following the injection of hypocretin. Therefore, we suggest that hypocretin-1 enhances ongoing states of wakefulness and their accompanying patterns of physiologic activity and that hypocretin-1 is also capable of promoting active sleep and the changes in various processes that occur during this state.

Citation:

Xi M; Chase MH. The injection of hypocretin-1 into the nucleus pontis oralis induces either active sleep or wakefulness depending on the behavioral state when it is administered. SLEEP 2010;33(9):1236-1243.     

Differential effect of orexins (hypocretins) on serotonin release in the dorsal and median raphe nuclei of freely behaving rats

Orexin (hypocretin)-containing neurons in the perifornical hypothalamus project to widespread regions of the brain, including the dorsal and median raphe nuclei [Peyron C, Tighe DK, van den Pol AN, de Lecea L, Heller HC, Sutcliffe JG, Kilduff TS (1998) Neurons containing hypocretin (orexin) project to multiple neuronal systems. J Neurosci 18:9996-10015; Wang QP, Koyama Y, Guan JL, Takahashi K, Kayama Y, Shioda S (2005) The orexinergic synaptic innervation of serotonin- and orexin 1-receptor-containing neurons in the dorsal raphe nucleus. Regul Pept 126:35-42]. Orexin-A or orexin-B was infused by reverse microdialysis into the dorsal raphe nucleus or median raphe nucleus of freely behaving rats, and extracellular serotonin was simultaneously collected by microdialysis and analyzed by high-performance liquid chromatography. We have found that orexin-A produced a dose-dependent increase of serotonin in the dorsal raphe nucleus, but not in the median raphe nucleus. However, orexin-B elicited a small but significant effect in both the dorsal raphe nucleus and median raphe nucleus. Orexins may have regionally selective effects on serotonin release in the CNS, implying a unique interaction between orexins and serotonin in the regulation of activities including sleep-wakefulness.