Characteristic neuronal firing interspike intervals in laterodorsal thalamic nuclei induced by tetanization of rat caudate putamen: possible relations to hippocampal electroencephalogram changes / 生理学报

The purpose of the present work was to study the effect of acute tetanization of the right caudate putamen nucleus (ATRC) on single neuronal interspike intervals (ISIs) in both laterodorsal thalamic nuclei (LDi), and electroencephalogram (EEG) wave interpeak intervals (IPIs) in both hippocampi (HPCi). Experiments were performed on 21 male Sprague-Dawley rats weighing 150~250 g. The seizures were induced by the ATRC (60 Hz, 2 s, 0.4~0.6 mA). Quadruple recordings were simultaneously carried out: two for single unit recordings from both LDi, and two for EEG recordings from both HPCi. The ATRC induced: (1) An interactive epileptic electrical network reconstructed in bilateral HPCi, which was driven by primary afterdischarges of single LD neuron. (2) A symmetric mirror-like ISI spot distribution of the LD neuronal firing before and after tetanus. (3) Gradually prolonged LD neuronal discharge intermittence was coherent with synchronous hippocampal EEG activities on the contralateral side. (4) Single LD neuronal spikes were phase- and time-locked to 20~25 Hz gamma oscillations in contralateral HPC. It suggests a particular temporal code patterning of single LD neuronal firing and its relationships to hippocampal EEG wave code in time series, the latter implies the LD neuronal encoding mechanisms of ATRC-induced epileptic electrical network in bilateral HPCi.

Microinjection of adrenomedullin into rostral ventrolateral medulla increases blood pressure, heart rate and renal sympathetic nerve activity in rats / 生理学报

The present study was undertaken to examine the effects of microinjection of adrenomedullin (AM) into rostral ventrolateral medulla (RVLM) on mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) in 34 anesthetized Sprague-Dawley rats. The results obtained are as follows. (1) Following microinjection of AM (10 micromol/L, 200 nl) into the RVLM, MAP, HR and RSNA were significantly increased from 99.09+/-3.32 mmHg, 370.78+/-7.84 bpm and 100+/-0% to 113.57+/-3.64 mmHg (P>0.001), 383.28+/-7.38 bpm (P>0.001) and 123.72+/-2.74% (P>0.001), respectively. (2) Pretreatment with microinjection of calcitonin gene-related peptide receptor antagonist CGRP8-37 (100 micromol/L, 200 nl) did not change the effects of AM. (3) L-arginine (100 mg/kg, 0.2 ml, i.v.), an NO precursor, abolished the effects of AM. This study demonstrates that AM acting at the rostral ventrolateral medulla may produce significant cardiovascular responses, the effects are not mediated by CGRP receptor but may be abolished by NO.

Effect of (R-)-N6-phenylisopropyladenosine (RPIA) Pretreatment on the alteration of Netural Cell dhesion Molecule / 대한간질학회지

BACKGROUND: Various neuronal and glial factors which participate in neural differentiation, including neural cell adhesion molecule (NCAM), are upregulated in pathogenesis of temporal lobe epilesy (TLE).This study aimed to investigate hte effect of (R-)-N6-phenylisopropyladenosine (RPIA), an adenosine A1 receptor agonist, on the morphological alteration of NCAM immunoreactivity (IR) in limbic system of Kainic acid (KA)-induced epileptic rats. METHODS: Experiment animals were divided into control group, KA treatment only (10 mg/kg. i.p.)group, and RPIA pretreatment (100 microgram/kg. i,p, 10 min prior to injection of KA) group. Animals were sacrificed at 24 hours and 1 week after KA treatment. Luxol fast blue-cresyl violet stain for histopathological observation, and NCAM immunohistochemistry to study alteration of NCAM IR in limbic system were performed. RESULTS: Neuronal loss in CA1 and CA3areas of hippocampus, piridorm cortex, basolateral amygdala nucleus and lateral dorsal thalamic nucleus were induced by KA unjection, and thoes were reduced by RPIA pretreatment. Inrease of NCAM-IR was observed in interneurons of all hippocampal areas. except CA2 area, pirform cortex and basolateral amygdala nucleus at 24 hours after KA injection. and increased NCAM-IR was observed in cell membrane and processes of neuroglia, dentate granule cells and pyramidal cells in CA1 area of hippocampus. and neurons in piriform cortex, amygdala and lateral dorsal thalamic nucleus 1 week after KA injection, but those changes were milder than those at 24 hours after KA injection. RPIA pretreatment significantly reduced KA-induced NCAM-IR in hippocampal CA3, CA1 area, piriform cortex, amtgdala and lateral dorsal thalamic nucleus. CONCLUSION: We suggest that decrease of NCAM immunoreactivity is associated with neuprotective effects of RPIA on limbic system against KA neurotoxiciy.

Cloning and localization of two forms of voltage-dependent calcium channel beta3 subunit gene / 대한해부학회지

Voltage-dependent calcium channel (VDCC) is composed of at least four subunits: alpha1, alpha2, beta, delta. Four mammalian beta subunit isoforms (beta1, beta2, beta3 and beta4) have been identified from nervous system. beta subunit accelerates the kinetics of activation (channel openning) and inactivation (channel closure), and regulates the channel activity by phosphorylation through various signal transduction mechanisms. We have cloned three cDNAs (RB8, RB10, and RB11) encoding beta3 subunit of voltage-dependent calcium channel from rat cDNA library using the oligonucleotides of which sequences obtained from the highly conserved regions of rat b subunits. The RB8 and RB10 (rtB3a) encode a same protein of 484 amino acids with estimated Mr of 54,571 Da, which was identical to beta3 subunit gene previously reported. The RB11 (rtbBb) is diffferent from RB10 at N-terminal region but shares common amino acid sequences from the glycine, the 16th amino acid of RB10, to the end of the gene. Open reading frame of RB10 encodes a 483 amino-acid protein with a predicted Mr of 54,473 Da. The RB10 and RB11 are suspected to be alternatively spliced variants from a single b3 subunit gene. The existence of the variants was confirmed by RT-PCR using the oligonucleotide primers from the specific sequences of each variant. The expression patterns of VDCC beta3 (rtB3a) and its specific variant (rtB3b) were investigated in the rat brain by in situ hybridization histochemistry. The mRNAs for rtB3a and rtB3b were exclusively expressed in the nervous system. In the brain, strong expression of both mRNAs (rtB3a and rtB3b) was found in the medial habenular nucleus of thalamus, hippocampus, dentate gyrus, olfactory bulb and cerebellum. But significant discrepancy of expression was found in the lateral posterior thalamic nucleus and olfactory bulb. From these results, it is suspected that newly cloned VDCC variant (rtB3b) should be the alternatively spliced variant of VDCC beta3 gene.

Immunocytochemical Study on the Monoaminergic Innervation of Diencephalic Visual Structures in the Squirrel Monkey

This study was for investigating relations between distributions of monoamines-norepinephrine, serotonin, and dopamine-on the visual system and their functions. Distributions of these monoamines in the lateral geniculate body, pulvinar, lateral posterior nucleus, and suprachiasmatic nucleus were investigated. Brain of a squirrel monkey was removed and frozen sectioned. Immunocytochemical study was performed for the tissue of the brain. Results showed that the anterior part of the lateral geniculate body contained more monoamines than the posterior part. More serotonins were distrbuted at the magnocellular part, and more dopamines were found at the parvocellular part. In pulvinar, more norepinephrines were distributed at the medial part, while serotonins were evenly distributed at all parts. In lateral posterior nucleus and suprachiasmatic nucleus, three kinds of monoamines were distributed with high density. Among the three, density of the serotonin showed the highest value. The lateral geniculate body relates with visual perception such as visual acuity, form and color perception, and stereopsis, while the pulvinar relates with visual functions, such as visual attention, sensory integration, and differentiation. Since norepinephrine and serotonine are distributed with high density in the pulvinar than in the lateral geniculate body those two monoamines are expected to playa major role for visual functions. Inferior part of the pulvinar relates with visual imagination, and the lateral posterior nucleus relates with integration of visual sensory. Relatively high distribution of dopamine in these two parts means that dopamine may playa major role for visual imagination and integration. As suprachiasmatic nucleus relates with controlling biorhythm, dense distribution of monoamines in suprachiasmatic nucleus implies that the monoamines may work for controlling biorhythm.