Binucleated neurons in the central nervous system of the laboratory animals

Summary Binucleated neurons were studied in the central nervous system of the rat and the rabbit. They were present in the young as well as the adult animals. The animals injected with thymidine-H³ during their embryonic development showed labelled binucleated neurons. It is suggested that the neurons become binucleated during neuroembryogenesis, and differentiate into normal neurons morphologically and physiologically.Supported by NIH Research grant No. NS-08817-05.     

Neurotrophic effects of conditioned media of astrocytes isolated from different brain regions on hippocampal and cortical neurons

The present study was designed to reveal whether astroglial cells from different brain regions produce diffusible factors that differentially support the survival of neurons and the establishment of neuronal morphology. For this purpose, astrocyte conditioned media (ACM) were prepared by conditioning chemically-defined medium with type I astrocyte culture dissociated from cerebral cortex, hippocampus and hypothalamus. Hippocampal and cortical neurons were cultured in ACM or in non-conditioned medium. ACM derived from three brain regions all supported the survival of hippocampal and cortical neurons better than non-conditioned control medium. Of these, hypothalamic ACM was the most effective in supporting the survival of cortical neurons. The ACM also potentiated the elongation of the longest neurite of hippocampal and cortical neurons. However, there were no significant differences in the promoting effects on neurite elongation among ACM from three brain regions.     

Activity of bulbar respiratory modulated neurons and restart of respiration after hypocapnic apnea in rabbits

Summary The activity of respiratory modulated neurons at the end of the apneic pause and during restart of respiration and the diaphragmatic mass activity were examined and both were compared to quiet respiration. Thresholds of mutual inhibition of neurons are unevenly distributed within various phase types of neurons.     

Electrophysiologic and anatomic demonstration of inhibitory commisural vestibular neurons in the tench (Tinca tinca)]

Horseradish peroxydase was injected intracellularly in some of the medullary neurons which, in Fish, exhibit a passive hyperpolarizing potential after spinal cord stimulation (this indicates that such neurons both electrical and chemical inhibitions of the Mauthner cells). With positive staining, commissural vestibular neurons were identified; their axons cross the midline and they establish connexions with the Mauthner cell and with vestibular neurons of both sides. Thus the existence of a crossed vestibular inhibitory pathway, previously suggested by electrophysiological studies in lower Vertebrates as well as in Mammals, is now correlated with histological evidence.     

Absence of a robust innate immune response in rat neurons facilitates persistent infection of Borna disease virus in neuronal tissue

Borna disease virus (BDV) persistently infects neurons of the central nervous system of various hosts, including rats. Since type I IFN-mediated antiviral response efficiently blocks BDV replication in primary rat embryo fibroblasts, it has been speculated that BDV is not effectively sensed by the host innate immune system in the nervous system. To test this assumption, organotypical rat hippocampal slice cultures were infected with BDV for up to 4 weeks. This resulted in the secretion of IFN and the up-regulation of IFN-stimulated genes. Using the rat Mx protein as a specific marker for IFN-induced gene expression, astrocytes and microglial cells were found to be Mx positive, whereas neurons, the major cell type in which BDV is replicating, lacked detectable levels of Mx protein. In uninfected cultures, neurons also remained Mx negative even after treatment with high concentrations of IFN-α. This non-responsiveness correlated with a lack of detectable nuclear translocation of both pSTAT1 and pSTAT2 in these cells. Consistently, neuronal dissemination of BDV was not prevented by treatment with IFN-α. These data suggest that the poor innate immune response in rat neurons renders this cell type highly susceptible to BDV infection even in the presence of exogenous IFN-α. Intriguingly, in contrast to rat neurons, IFN-α treatment of mouse neurons resulted in the up-regulation of Mx proteins and block of BDV replication, indicating species-specific differences in the type I IFN response of neurons between mice and rats.     

Nerve-mediated action of forskolin on guinea pig ileal mucosa

The effects of forskolin on myenteric neuronal activity and mucosal function were examined in guinea pig ileum. Forskolin increased the excitability of myenteric neurons, and increased mucosal chloride secretion by stimulating enteric neurons as well as by acting directly on enterocytes.     

Modification of visual signals by nigral stimulation

Summary Responses of the lateral geniculate neurons to light were modified by stimulation of the substantia nigra. Nigral stimulation often caused enhancement of firing in neurons responding primarily to flash, but it usually had the contrary effect on units inhibited by light.     

Electrophysiology of mammalian hypothalamic and interpeduncular neurons in vitro.

Electrical activities of the hypothalamic and interpeduncular neurons were studied in vitro in brain slices prepared from the guinea-pig brain stem. Neurons preserved resting membrane potentials comparable to those of neurons in vivo, responded to stimulation of the afferent fibres, and retained stable spontaneous firings for more than several hours.     

Long-term depressor effects of noradrenaline and dopamine neurons transplanted into the third ventricle of the brain of salt-loaded hypertensive rats

Neural tissues including A 6 group noradrenaline neurons in the locus ceruleus or A 10 group dopamine neurons in the substantia nigra were transplanted into the third ventricle at the preoptic-anterior hypothalamic level of rats made hypertensive by salt loading. Either transplant exerted a long-lasting depressor effect.     

Modification of visual signals by nigral stimulation.

Responses of the lateral geniculate neurons to light were modified by stimulation of the substantia nigra. Nigral stimulation often caused enhancement of firing in neurons responding primarily to flash, but it usually had the contrary effect on units inhibited by light.     

Electrophysiology of mammalian hypothalamic and interpeduncular neurons in vitro

Summary Electrical activities of the hypothalamic and interpeduncular neurons were studied in vitro in brain slices prepared from the guinea-pig brain stem. Neurons preserved resting membrane potentials comparable to those of neurons in vivo, responded to stimulation of the afferent fibres, and retained stable spontaneous firings for more than several hours.     

Immunocytochemical localization of neurons containing ACTH 17-39 in the rat brain]

Immunoreactive neurons and fibers were localized in the Rat brain by immunocytochemistry using an anti-ACTH 17-39 antiserum. Neither adrenalectomy nor water deprivation affected intensity of distribution of reaction of labelled neurons whereas colchicine increased labelling of hypothalamic perikarya. These results support the neuronal origin of cerebral ACTH.     

Long-term depressor effects of noradrenaline and dopamine neurons transplanted into the third ventricle of the brain of salt-loaded hypertensive rats

Summary Neural tissues including A 6 group noradrenaline neurons in the locus ceruleus or A 10 group dopamine neurons in the substantia nigra were transplanted into the third ventricle at the preoptic-anterior hypothalamic level of rats made hypertensive by salt loading. Either transplant exerted a long-lasting depressor effect.     

Differential effects of the serotonin receptors on cultured rat cerebral cortical neurons

Effects of serotonin (5-HT) on cerebral cortical neurons were examined by patch clamp techniques. 5-HT produced a variety of responses such as outward (19/73 patches/neurons), slow inward (15/73 patches/neurons), fast inward (8/73 patches/neurons), and mixed currents (initially fast inward deflection followed by an outward response: 2/73 patches/neurons), with a latency of 12 sec, 15 sec, 0 sec, and 0 sec respectively, at a holding potential of −60 mV in whole-cell patches. The fast inward currents were again evoked by a selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide hydrochloride (CPBG). In the cell-attached patch clamp configuration, 5-HT inside the patch pipette elicited single channel currents with slope conductances of 42 pS and 132 pS (4/42 patches/neurons). CPBG inside the patch pipette evoked inward single channel currents with a lower slope conductance of 41 pS (3/23 patches/neurons). In contrast, application of 5-HT or a 5-HT₂ receptor agonist, α-methyl-5-hydroxytryptamine-maleate, outside the patch pipette induced outward single channel currents with a major slope conductance of 140 pS (8/30 patches/neurons) or 135 pS (6/20 patches/neurons), respectively. These results indicate that the outward and fast inward currents may be mediated respectively by the 5-HT₂ receptor, which is coupled to a G-protein, and by the 5-HT₃ receptor, which contains the non-selective cation channel, and that the mixed type may be caused by both the 5-HT₂ and 5-HT₃ receptors. Received 27 September 1996; received after revision 4 November 1996; accepted 7 November 1996     

Immunocytochemical characterization of vasotocin and mesotocin secretory systems in duck brain

The neural systems secreting vasotocin and mesotocin has been characterized in the Duck brain with indirect immunofluorescent techniques, using specific antisera. In the anterior preoptic region and in supraoptic and paraventricular nuclei, neurons producing vasotocine and neurons producing mesotocine have been identified separately. Only vasotocinergic neurons were localized in ectomammillary tract. Vasotocin--and mesotocin--containing axons together enter the median eminence, some of them crossed the internal zone of the median eminence before ending in the posterior lobe of the pituitary, whereas other axons of both classes entered the external layer of the rostral median eminence, in close contact with the capillaries of the hypophysial portal system.     

Further support for the postsynaptic action of substance P and its blockade with baclofen in neurons of the guinea-pig hypothalamus in vitro

Effects of substance P on neurons of the guinea-pig hypothalamus in vitro and antagonism between substance P and baclofen were investigated. Substance P increased the firing rate of neurons in the medium containing 0 mM Ca2+ and 12 mM Mg2+. The excitatory action of substance P was antagonized by a low dose of baclofen whereas that of acetylcholine was not antagonized even by much higher doses of baclofen.     

Optical monitoring of activity of many neurons in invertebrate ganglia during behaviors

Optical methods for monitoring neuron activity were developed because these methods lend themselves to simultaneous multiple-site measurements. With the use of new voltage-sensitive dyes, the dye-related pharmacology and photodynamic damage appear to be relatively unimportant. Using multiple-site measurements made with a 124-element photodiode array, we estimated that approximately 30 of the 200 neurons present in the Navanax buccal ganglion make action potentials during feeding and that approximately 300 of the 1100 neurons present in the Aplysia abdominal ganglion are active during the gill-withdrawal reflex. The fact that a light mechanical touch to the siphon skin activated such a large number of neurons in the abdominal ganglion suggests that understanding the neuronal basis of the gill-withdrawal reflex and its behavioral plasticity may be forbiddingly difficult.     

Demonstration of a 2d LH-RH neurosecretory system in the duck hypothalamus]

Using immunocytochemical techniques with an anti-LH-RH immuneserum, evidence of two neuronal systems secreting LH-RH has been shown in the Duck hypothalamus. In addition to the previously described system, located in the preoptic nucleus, a second system could be demonstrated in the infundibular nucleus. The perikarya of the infundibular LH-RH producing neurons were significantly smaller than those of the preoptic neurons. On the other hand, under the experimental conditions used, the infundibular system had approximately five times less LH-RH secreting neurons than the preoptic system, and its perikarya appeared less heavily loaded in IR LH-RH. The LH-RH containing axons from both neuronal populations ran down to the external layer of the median eminence, where they ended in close contact with the capillaries of the hypophysial portal system.     

Role of extracellular matrix molecules in the development of the sodium current in quail mesencephalic neural crest cells

The occurrence of the voltage-dependent sodium current has been studied in developing neurons from quail mesencephalic neural crest on different substrates, using the whole-cell patch clamp technique. Explants from 9–12 somite embryos were cultured on dishes coated with type I collagen, fibronectin, laminin or on plastic dishes in a chemically defined medium. After 18 h of culture the sodium current was observed in 70% of the neurons tested, and at 24 h some of these neurons were able to generate an action potential. After 18–25 h cells grown on fibronectinor collagen I-coated dishes showed a significantly higher occurrence of the sodium current (83% and 84% respectively) as compared to cells grown on uncoated plastic dishes (51%). Moreover, in the presence of fibronectin, the current density of the sodium current was more than doubled in comparison with cells grown on other substrates.     

慢病毒介导的CBS基因过表达对原代皮质神经元β淀粉样蛋白分泌的影响

目的通过过表达手段上调胱硫醚β-合成酶(Cystathionine-β-synthase,CBS)在原代神经元细胞中的表达,观察其对原代神经元β淀粉样蛋白(Aβ)分泌的影响。方法使用过表达CBS慢病毒载体感染体外培养的原代皮质神经元,设定为慢病毒介导阳性(CBS)组、另设阴性对照慢病毒感染(NC)组、未经慢病毒感染(CON)组。采用实时荧光定量PCR检测CBS基因mRNA的表达,Western blot检测CBS蛋白的表达,采用Elisa检测Aβ40的表达水平。结果使用过表达CBS的慢病毒载体感染体外培养的神经元,实时荧光定量PCR检测其mRNA的表达上调明显升高,与NC组和CON组相比差异有统计学意义(P0.01),Western blot结果显示蛋白表达升高与定量PCR一致,Elisa检测感染72小时后CBS组、NC组、CON组Aβ40的分泌分别为(182.19±24.52)ng/L、(411.90±12.43)ng/L、(390.41±54.53)ng/L,CBS组与NC组和CON组相比差异有统计学意义(P0.05)。结论慢病毒介导的CBS基因过表达可降低原代皮质神经元Aβ40的分泌。