PMID- 9497415
OWN - NLM
STAT- MEDLINE
DCOM- 19980424
LR  - 20181201
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 79
IP  - 3
DP  - 1998 Mar
TI  - Ontogenesis of presynaptic GABAB receptor-mediated inhibition in the CA3 region 
      of the rat hippocampus.
PG  - 1341-8
AB  - gamma-Aminobutyric acid-B(GABAB) receptor-dependent and -independent components 
      of paired-pulse depression (PPD) were investigated in the rat CA3 hippocampal 
      region. Intracellular and whole cell recordings of CA3 pyramidal neurons were 
      performed on hippocampal slices obtained from neonatal (5-7 day old) and adult 
      (27-34 day old) rats. Electrical stimulation in the hilus evoked monosynaptic 
      GABAA postsynaptic currents (eIPSCs) isolated in the presence of the ionotropic 
      glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 
      microM) and D(-)2-amino-5-phosphovaleric acid (-AP5, 50 microM) with 
      2(triethylamino)-N-(2,6-dimethylphenyl) acetamine (QX314) filled electrodes. In 
      adult CA3 pyramidal neurons, when a pair of identical stimuli was applied at 
      interstimulus intervals (ISIs) ranging from 50 to 1,500 ms the amplitude of the 
      second eIPSC was depressed when compared with the first eIPSC. This paired-pulse 
      depression (PPD) was partially blocked by P-3-aminoprophyl 
      -P-diethoxymethylphosphoric acid (CGP35348, 0.5 mM), a selective GABAB receptor 
      antagonist. In neonates, PPD was restricted to ISIs shorter than 200 ms and was 
      not affected by CGP35348. The GABAB receptor agonist baclofen reduced the 
      amplitude of eIPSCs in a dose-dependent manner with the same efficiency in both 
      adults and neonates. Increasing the probability of transmitter release with high 
      Ca2+ (4 mM)/low Mg2+ (0.3 mM) external solution revealed PPD in neonatal CA3 
      pyramidal neurons that was 1) partially prevented by CGP35348, 2) independent of 
      the membrane holding potential of the recorded cell, and 3) not resulting from a 
      change in the reversal potential of GABAA eIPSCs. In adults the GABA uptake 
      blocker tiagabine (20 microM) increased the duration of eIPSCs and the magnitude 
      of GABAB receptor-dependent PPD. In neonates, tiagabine also increased duration 
      of eIPSCs but to a lesser extent than in adult and did not reveal a GABAB 
      receptor-dependent PPD. These results demonstrate that although GABAB 
      receptor-dependent and -independent mechanisms of presynaptic inhibition are 
      present onGABAergic terminals and functional, they do not operate at the level of 
      monosynaptic GABAergic synaptic transmission at early stages of development. 
      Absence of presynaptic autoinhibition of GABA release seems to be due to the 
      small amount of transmitter that can access presynaptic regulatory sites.
FAU - Caillard, O
AU  - Caillard O
AD  - Institut National de la Sant et de la Recherche M dicale U29, H pital de 
      Port-Royal, 75014 Paris, France.
FAU - McLean, H A
AU  - McLean HA
FAU - Ben-Ari, Y
AU  - Ben-Ari Y
FAU - Gaiarsa, J L
AU  - Gaiarsa JL
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
RN  - 0 (GABA Antagonists)
RN  - 0 (Neurotransmitter Uptake Inhibitors)
RN  - 0 (Nipecotic Acids)
RN  - 0 (Organophosphorus Compounds)
RN  - 0 (Receptors, GABA-B)
RN  - 56-12-2 (gamma-Aminobutyric Acid)
RN  - 6OTE87SCCW (6-Cyano-7-nitroquinoxaline-2,3-dione)
RN  - 76726-92-6 (2-Amino-5-phosphonovalerate)
RN  - 87TI61875H (CGP 35348)
RN  - H789N3FKE8 (Baclofen)
RN  - SY7Q814VUP (Calcium)
RN  - Z80I64HMNP (Tiagabine)
SB  - IM
MH  - 2-Amino-5-phosphonovalerate/pharmacology
MH  - 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
MH  - Aging/*physiology
MH  - Animals
MH  - Animals, Newborn
MH  - Baclofen/pharmacology
MH  - Calcium/pharmacology
MH  - Electric Stimulation
MH  - Evoked Potentials/drug effects/*physiology
MH  - GABA Antagonists/*pharmacology
MH  - Hippocampus/growth & development/*physiology
MH  - In Vitro Techniques
MH  - Male
MH  - Neurotransmitter Uptake Inhibitors/pharmacology
MH  - Nipecotic Acids/pharmacology
MH  - Organophosphorus Compounds/pharmacology
MH  - Pyramidal Cells/drug effects/*physiology
MH  - Rats
MH  - Rats, Wistar
MH  - Receptors, GABA-B/*physiology
MH  - Synaptic Transmission/drug effects/*physiology
MH  - Tiagabine
MH  - gamma-Aminobutyric Acid/physiology
EDAT- 1998/05/02 00:00
MHDA- 1998/05/02 00:01
CRDT- 1998/05/02 00:00
PHST- 1998/05/02 00:00 [pubmed]
PHST- 1998/05/02 00:01 [medline]
PHST- 1998/05/02 00:00 [entrez]
AID - 10.1152/jn.1998.79.3.1341 [doi]
PST - ppublish
SO  - J Neurophysiol. 1998 Mar;79(3):1341-8. doi: 10.1152/jn.1998.79.3.1341.