Fig. 3

BDNF exposure affects pre-synaptic release. In (a) sample tracings of simultaneous pair recordings: top, evoked monosynaptic GABAergic PSCs in Control (black) and glutamate-AMPA receptor mediated in BDNF-treated (blue) cultures; bottom, presynaptic induced action potentials. In (b) plots summarize the probability of finding evoked GABA_A- or AMPA- receptor mediated pair recordings in Control (grey) or BDNF (blue) treated cultures. In (c) is summarized the paired-pulse ratio (PPR) of GABA_A- or AMPA-mediated PSCs measured in Control and BDNF treated pairs. In (d) sequence of images Control, above and BDNF, below: sequential FM1–43 staining and destaining: (left image) bright field images show the extensive neurite arborization that hippocampal neurons reach at 9÷10 DIV culture; (middle image): the same fields after staining with FM1–43; (right image): fluorescence images following destaining induced by 50 mM KCl. Remaining fluorescence represents non-specific staining. In (e) histograms summarized the averaged fluorescence intensity when loaded with FM1–43. BDNF-treated cells showed a significant increase (P < 0.001, Mann-Whitney test) compared to Control cultures. In (f) the rate of synaptic release from synaptic terminals, following KCl stimulation, in Control (black line) and BDNF (blue line) cultures. In grey the natural fluorescent bleaching after KCl stimulation. In (g) representative single de-staining fast (orange line) and slow (pink) profiles, based on their kinetics properties. In (h) plots summarize the distribution of fast and slow events in Control (grey) and BDNF-treated (blue) cultures. Note that in BDNF-treated cells prevailed fast events (on the left), while in Control cultures, the large majority displayed slow events (on the right)