Figure 4

Expression levels of TrkB and P/Q-type Ca²⁺ channels are unchanged in PV-INs of BMPR1a/1b (c) DKO mice. (A) FISH images of coronal brain sections at two magnifications (left, and right), for a control mouse at P25 (bregma, ~−2.1 mm), and for a BMPR1a/1b (c)DKO mouse at P25 (bregma, ~−2.4 mm). The red and the blue channels show the FISH probe for tdTomato (indicating PV-INs) and DAPI, respectively. “A1 ctx”, auditory cortex. (B) FISH images at higher magnification for a control mouse at P25 (top) and for a BMPR1a/1b (c)DKO mouse at P25 (bottom), showing, from left to right, the tdTomato probe channel with two PV-positive neurons each, the DAPI channel, the Ntrk2 channel, and the Cacna1A probe channel. Red arrowheads show nascent transcripts of Ntrk2 in the nucleus which were excluded from the quantifications. (C) The density of PV-INs within 20–50% depth of auditory cortex was unchanged between N = 3 control mice (left, black data points), and N = 4 BMPR1a/1b (c)DKO mice (right, red data points). (D) Left, individual - and average data of the normalized number of Ntrk2 transcript dots for n = 9 PV-INs each from a control mouse (black data points), and from a BMPR1a/1b (c) DKO mouse (red data points). Right, averaged data from N = 3 control mice (left) and from N = 4 BMPR1a/1b (c)DKO mice (right). (E) Similar data as in (D), here for Cacna1A transcript levels, the gene which codes for the α-subunit of the P/Q-type Ca²⁺ channel. (F,G) Example paired recordings in which the P/Q-type Ca²⁺ channel blocker ω-agatoxinIVa (200 nM) was applied, followed by the application of the same toxin plus 100 µM CdCl₂. Note that unitary IPSCs are almost completely blocked by ω-agatoxin-IVa in both genotypes. The inset shows traces of presynaptic APs (top, only for control conditions), and of postsynaptic IPSCs before - (middle) and after application of ω-agatoxinIVa (bottom). For statistical analysis and number of recordings, see Results.