Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Nigral GABAergic inhibition upon cholinergic neurons in the rat pedunculopontine tegmental nucleus (2003)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 18 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We investigated, in a midbrain parasagittal slice preparation of Wistar rats (postnatal day 9–17), the synaptic inhibition of neurons in the pedunculopontine tegmental nucleus (PPN), which was mediated by gamma (γ)-amino-butyric acid (GABA). Whole-cell patch-clamp recording was used, in combination with a single-cell reverse transcription-polymerase chain reaction amplification technique, to record synaptic potentials and to identify the phenotype of the recorded PPN neuron. In the presence of the ionotropic glutamate receptor antagonists, 6-cyano-2, 3-dihydroxy-7-nitro-quinoxaline-2, 3, dione, and dl-2-amino-5-phosphonovaleric acid, single electrical stimuli were applied to the substantia nigra pars reticulata (SNr), one of the basal ganglia output nuclei. Stimulation of the SNr evoked inhibitory postsynaptic potentials (IPSPs) in 73 of the 104 neurons in the PPN. The IPSPs were abolished with a GABAA receptor antagonist, bicuculline. Inhibitory postsynaptic currents of the neurons were reversed in polarity at approximately −93.5 mV, which was close to the value of the equilibrium potential for chloride ions of −88.4 mV. Single-cell reverse transcription-polymerase chain reactions revealed that approximately 30% (9/32) of the PPN neurons that received inhibition from the SNr expressed detectable levels of choline acetyltransferase mRNA. These findings show that output from the SNr regulates the activity of cholinergic PPN neurons through GABAA receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02825.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Nigral GABAergic inhibition upon mesencephalic dopaminergic cell groups in rats (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Synaptic inhibition from the substantia nigra pars reticulata (SNr) to the mesencephalic dopaminergic neurons, which was mediated by gamma (γ)-amino-butyric acid (GABA), was investigated in a midbrain slice preparation of Wistar rats. Whole-cell patch-clamp recordings were used to record synaptic potentials/currents from the dopaminergic neurons (n = 93) located in the retrorubral field (n = 22), the substantia nigra pars compacta (n = 47) and the ventral tegmental area (n = 24). In the presence of ionotropic glutamate receptor antagonists electrical stimulation of the SNr induced inhibitory postsynaptic potentials (IPSPs) and/or currents (IPSCs) in 83 neurons. The IPSPs/IPSCs were comprised early and late components. The early IPSPs/IPSCs were mediated by chloride currents through GABAA receptors. The late IPSPs/IPSCs were mediated by potassium currents through GABAB receptors. Both GABAA- and GABAB-IPSPs were amplified by repetitive stimuli with frequencies between 25 and 200 Hz. This frequency range covers the firing frequencies of SNr neurons in vivo. It was observed that an application of a GABAB receptor antagonist increased the amplitude of the GABAA-IPSPs. The amplification was followed by a rebound depolarization that induced transient firing of dopaminergic neurons. These properties of the IPSPs were common in all of the three dopaminergic nuclei. These results suggest that postsynaptic GABAA- and GABAB-inhibition contribute to transient and persistent alternations of the excitability of dopaminergic neurons, respectively. These postsynaptic mechanisms may be, in turn, regulated by presynaptic GABAB-inhibition. Nigral GABAergic input may provide the temporospatial regulation of the background excitability of mesencephalic dopaminergic systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0953-816X.2004.03337.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Discharge properties of medullary reticulospinal neurons during postural changes induced by intrapontine injections of carbachol, atropine and serotonin, and their functional linkages to hindlimb motoneurons in cats (1994)
    Springer
    Experimental brain research 99 (1994), S. 361-374 
    Details
    ISSN: 1432-1106
    Keywords: Carbachol ; Serotonin ; Pontine reticular formation ; Medullary reticulospinal neuron ; Postural atonia ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study was aimed at elucidating the pontomedullary and spinal cord mechanisms of postural atonia induced by microinjection of carbachol and restored by microinjections of serotonin or atropine sulfate into the nucleus reticularis pontis oralis (NRPo). Medullary reticulospinal neurons (n=132) antidromically activated by stimulating the L1 spinal cord segment were recorded extracellularly. Seventy-eight of them were orthodromically activated with mono- or disynaptic latencies by stimulating the NRPo area at the site where carbachol injections effectively induced postural atonia. Most of these reticulospinal neurons (71 of 78) were located in the nucleus reticularis gigantocellularis (NRGc). Following carbachol injection into the NRPo, discharge rates of the NRGc reticulospinal neurons (29 of 34) increased, while the activity of soleus muscles decreased bilaterally. Serotonin or atropine injections into the same NRPo area resulted in a decrease in the discharge rates of the reticulospinal neurons with a concomitant increase in the levels of hindlimb muscle tone. Membrane potentials of hindlimb extensor and flexor alpha motoneurons (MNs) were hyperpolarized and depolarized by carbachol and serotonin or atropine injections, respectively. In all pairs of reticulospinal neurons and MNs (n=11), there was a high correlation between the increase in the discharge rates and the degree of membrane hyperpolarization of the MNs. Spike-triggered averaging during carbachol-induced atonia revealed that inhibitory postsynaptic potentials (IPSPs) were evoked in 15 MNs by the discharges of nine reticulospinal neurons. Four of them evoked IPSPs in more than one MN. The mean segmental delay and the mean time to the peak of IPSPs were 1.6 ms and 2.0 ms, respectively. Axonal trajectories of reticulospinal neurons (n=6), which evoked IPSPs in MNs, were investigated in the lumbosacral segments (L1-S1) by antidromic threshold mapping. The stem axons descended through the ventral (n=2) and ventrolateral (n=4) funiculi in the lumbar segments. All axons projected their collaterals to the intermediate region (laminae V, VI) and ventromedial part (laminae VII, VIII) of the gray matter. All these results suggest that the reticulospinal pathway originating from the NRGc is involved in postural atonia induced by pontine microinjection of carbachol, and that the pathway is inactivated during the postural restoration induced by subsequent injections of serotonin or atropine. It is further suggested that the pontine inhibitory effect is mediated via segmental inhibitory interneurons projecting to MNs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228973
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synaptic mechanisms acting on lumbar motoneurons during postural augmentation induced by serotonin injection into the rostral pontine reticular formation in decerebrate cats (1993)
    Springer
    Experimental brain research 93 (1993), S. 471-482 
    Details
    ISSN: 1432-1106
    Keywords: Pontine reticular formation ; Serotonin ; Postural augmentation ; Alpha-motoneurons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intrapontine microinjections of serotonin in acutely decerebrated cats resulted in the bilateral augmentation of the postural muscle tone of the hindlimbs. Optimal injection sites were located in the dorsomedial part of the rostral pontine reticular formation corresponding to the nucleus reticularis ponds oralis (NRPo). In this study, attempts were made to elucidate the cellular basis for the serotoninergically induced augmentation of postural muscle tone by recording the electromyographic (EMG) activity of hindlimb extensor muscles, the monosynaptic reflex responses evoked by electrical stimulation of group Ia muscle afferent fibres and the membrane potentials of hindlimb alpha-motoneurons (MNs). Serotonin injections resulted not only in the augmentation of the EMG activity of gastrocnemius soleus muscles, but also in the restoration of EMG suppression, which was induced by previous injection of carbachol into the NRPo. Extensor and flexor monosynaptic reflex responses were facilitated by serotonin injections into the NRPo. Such reflex facilitation was not induced by serotonin injections into the mesencephalic or the medullary reticular formation. Intrapontine serotonin injections resulted in membrane depolarization of extensor and flexor MNs with decreases in input resistance and rheobase. Spontaneous depolarizing synaptic potentials (EPSPs) increased in both frequency and amplitude. Peak voltage of Ia monosynaptic EPSPs also increased. Serotonin injections which followed carbachol injections resulted in membrane depolarization of MNs along with an increase in the frequency of spontaneous EPSPs and a decrease in carbachol-induced inhibitory postsynaptic potentials. Following pontine carbachol injections, antidromic and orthodromic responses in MNs were suppressed. Discharges of MNs evoked by intracellular current injections were also suppressed, but were restored following serotonin injections. These results indicate that postsynaptic excitation, presynaptic facilitation and disinhibition (withdrawal of postsynaptic inhibition) simultaneously act on the hindlimb MNs during serotonin-induced postural augmentation and restoration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229362
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...