Portal de Periódicos da CAPES

γ-Aminobutyric acid (GABA): a fast excitatory transmitter which may regulate the development of hippocampal neurones in early postnatal life

1994; Elsevier BV; Linguagem: Inglês

10.1016/s0079-6123(08)60545-2

1875-7855

Yehezkel Ben‐Ari, Vadim Tseeb, D. Raggozzino, Roustem Khazipov, Jean‐Luc Gaïarsa,

Memory and Neural Mechanisms

This chapter reviews the properties of neonatal γ-aminobutyric acid (GABA)ergic synapses in neurones of the hippocampal CA3 region. GABA acting on GABAA, receptors, provides most of the excitatory drive on immature CA3 pyramidal neurones at an early stage of development, whereas glutamatergic synapses are mostly quiescent. Thus, during the first postnatal week of life, bicuculline fully blocked spontaneous and evoked depolarizing potentials, and GABA, receptor agonists depolarized CA3 pyramidal neurones. GABA, mediated currents also had a reduced sensitivity to benzodiazepines. In the presence of bicuculline, between P0 and P4, increasing the stimulus strength reveals an excitatory postsynaptic potential which is mostly mediated by N-methyl-D-aspartate receptors. During the same developmental period, pre- synaptic GABAB inhibition is present. Intracellular injections of biocytin showed that the axonal network of the GABAergic interneurones is well developed at birth, whereas the pyramidal recurrent collaterals are only beginning to develop. Finally, chronic bicuculline treatment of hippocampal neurones in culture reduced the extent of neuritic arborisation, suggesting that GABA acts as a trophic factor in that period.