Article

GABAA receptor-mediated tonic currents in substantia gelatinosa neurons of rat spinal trigeminal nucleus pars caudalis.

Department of Oral Physiology, School of Dentistry and Brain Korea 21, Brain Science and Engineering Institute, Kyungpook National University, 188-1 Samduk-2-ga, Chung-gu, Daegu 700-412, Republic of Korea.
Neuroscience Letters (impact factor: 2.11). 06/2008; 441(3):296-301. DOI:10.1016/j.neulet.2008.06.048 pp.296-301
Source: PubMed

ABSTRACT In the present study, we describe GABAA receptor-mediated tonic inhibitory currents in the substantia gelatinosa (SG) region of rat spinal trigeminal nucleus pars caudalis (Vc). The GABA(A) receptor-mediated tonic currents were identified by bath-application of the GABAA receptor antagonists, picrotoxin (1mM), SR95531 (100microM) and bicuculline (100microM). All three antagonists completely blocked outward spontaneous (phasic) inhibitory postsynaptic currents, but only picrotoxin and bicuculline induced a significant (>5pA) inward shift of holding currents at a holding potential (Vh) of 0mV in 60-70% of SG neurons, revealing the existence of tonic outward currents. The tonic currents were resistant to further the blockades of glycine receptors or those in addition to glutamate receptors and voltage-dependent sodium channels. An acute bath-application of THDOC (0.1microM), the stress-related neurosteroid, did enhance tonic currents, but only in a small population of SG neurons. In addition, slices incubated with THDOC for 30min increased the probability of neurons with significant tonic currents. The GABAergic tonic inhibition demonstrated in this study may play a significant role in the sensory processing system of the Vc.

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    Article: Participation of calbindin-D28K in nociception: results from calbindin-D28K knockout mice.
    Javier Egea, Eduardo Malmierca, Angelo O Rosa, Laura del Barrio, Pilar Negredo, Angel Nuñez, Manuela G López
    [show abstract] [hide abstract]
    ABSTRACT: Since calbindin-D(28K) (CB-D(28K))-positive neurons have been related to nociceptive sensory processing, we have hypothesized that altered CB-D(28K) expression could alter nociceptive transmission. We have used +/+ and -/- knockout (KO) mice for CB-D(28k) in different behavioral models of pain and sensory responses at the caudalis subdivision of the trigeminal spinal nucleus in order to understand how this protein may participate in nociception. Behavioral responses to formalin injection in the hind paw or at the whisker pad or in the hind paw glutamate or i.p. acetic acid tests showed an increase of the pain threshold in CB-D(28k) -/- mice. KO mice showed a diminution of the inhibitory activity at Sp5C nucleus and a marked reduction of GABA content. Sp5C neurons from CB-D(28k) -/- mice did not change their spontaneous activity or tactile response after formalin injection in the whisker pad. In contrast, Sp5C neurons increased their spontaneous firing rate and tactile response after formalin injection in their receptive field in CB-D(28k) +/+ mice. The results of this study demonstrate the active role played by CB-D(28k) in nociceptive sensory transmission. The lack of this calcium binding protein, associated to deficient GABAergic neurotransmission, translates into dysfunction of sensory processing of nociceptive stimuli.
    Pflügers Archiv - European Journal of Physiology 12/2011; 463(3):449-58. · 4.46 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

acute bath-application
 
bicuculline induced
 
GABAA receptor-mediated tonic inhibitory currents
 
GABAergic tonic inhibition
 
glutamate receptors
 
glycine receptors
 
holding potential
 
outward spontaneous
 
rat spinal trigeminal nucleus pars caudalis
 
sensory processing system
 
significant role
 
significant tonic currents
 
small population
 
stress-related neurosteroid
 
substantia gelatinosa
 
three antagonists
 
tonic currents
 
tonic outward currents
 
Vh
 
voltage-dependent sodium channels
 

Sang-Mi Han