Synaptojanin 1 contributes to maintaining the stability of GABAergic transmission in primary cultures of cortical neurons

A. Lüthi, G. Di Paolo, O. Cremona, L. Daniell, P. De Camilli, D. A. McCormick

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Inhibitory synapses in the CNS can exhibit a considerable stability of neurotransmission over prolonged periods of high-frequency stimulation. Previously, we showed that synaptojanin 1 (SJ1), a presynaptic polyphosphoinositide phosphatase, is required for normal synaptic vesicle recycling (Cremona et al., 1999). We asked whether the stability of inhibitory synaptic responses was dependent on SJ1. Whole-cell patch-clamp recordings of unitary IPSCs were obtained in primary cortical cultures between cell pairs containing a presynaptic, fastspiking inhibitory neuron (33.5-35°C). Prolonged presynaptic stimulation (1000 stimuli, 2-20 Hz) evoked postsynaptic responses that decreased in size with a bi-exponential time course. A fast component developed within a few stimuli and was quantified with paired-pulse protocols. Paired-pulse depression (PPD) appeared to be independent of previous GABA release at intervals of ≥100 msec. The characteristics of PPD, and synaptic depression induced within the first ∼80 stimuli in the trains, were unaltered in SJ1-deficient inhibitory synapses. A slow component of depression developed within hundreds of stimuli, and steady-state depression showed a sigmoidal dependence on stimulation frequency, with half-maximal depression at 6.0 ± 0.5 Hz. Slow depression was increased when release probability was augmented, and there was a small negative correlation between consecutive synaptic amplitudes during steady-state depression, consistent with a presynaptic depletion process. Slow depression was increased in SJ1-deficient synapses, with half-maximal depression at 3.3 ± 0.9 Hz, and the recovery was retarded -3.6-fold. Our studies establish a link between a distinct kinetic component of physiologically monitored synaptic depression and a molecular modification known to affect synaptic vesicle reformation.

Original languageEnglish
Pages (from-to)9101-9111
Number of pages11
JournalJournal of Neuroscience
Issue number23
Publication statusPublished - Dec 1 2001


  • Clathrin-mediated endocytosis
  • Inhibitory synaptic transmission
  • Phosphoinositide metabolism
  • Short-term plasticity
  • Synaptic depression
  • Synaptojanin
  • Vesicle recycling

ASJC Scopus subject areas

  • Neuroscience(all)


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