Fig. 1
A local GABAergic network in the ventral part of lateral septum (LSv) receives direct glutamatergic input from PVH neurons. a–c Sim1-Cre reporter mice (four males and two females) received injections of AAV-Flex-ChR2-eGFP vectors to one side of the PVH a, facilitating dual expression of the ROSA-lsl-tdTomato allele in Sim1-Cre neurons, and unilateral targeted expression of the AAV-Flex-ChR2-eGFP b. c GFP-expressing fibers from the PVH shown in the ventral part of lateral septum (LSv) were observed 4 weeks after AAV-delivery. d–k Patch clamp recording of randomly selected neurons in LSv in brain slices from Sim1-Cre d–j or Sim1-Cre::Vglut2flox/flox mice k with photostimulation of PVH→LSv fibers. d–f Voltage–clamp recordings for photostimulated (1 ms, blue ticks) excitatory postsynaptic currents (EPSCs) and their responses to glutamate receptor antagonists (CNQX+APV) d, GABA-A receptor antagonists (GABAzine) e, and 4-AP+TTX to block action potentials f. g–j Voltage–clamp recordings with photostimulation (1 ms, blue ticks) to monitor inhibitory postsynaptic currents (oIPSCs) and their responses to GABAzine g, CNQX+APV h, 4-AP+TTX i and j. i and j showed the recording from the same set of neurons with complete i or partial blockage j by 4-AP/TTX. k Only three out of 25 recorded neurons showed 4-AP/TTX-resistant IPSC in Sim1-Cre::Vglut2flox/flox mice. The ratios at the top of traces indicate the number of neurons that exhibited responses to drugs out of all neurons showing postsynaptic currents. l A diagram derived from the recording data depicting a GABAergic network in the LSv receiving monosynaptic projections from the PVH comprising a major glutamatergic, and minor GABAergic components. Scale bar = 100 µm. PVH: paraventricular hypothalamus; LSv: ventral part of lateral septum; MS; medial septum; HDB and VDB: diagonal band (horizontal and vertical); LV: lateral ventricle; 3 V: the third ventricle; AcbSh: accumbens shell
