Fig. 4: SST neurons project to PENK neurons and receive inputs from CCK neurons. | Nature Communications

Fig. 4: SST neurons project to PENK neurons and receive inputs from CCK neurons.

From: A cell-type-specific circuit of somatostatin neurons in the habenula encodes antidepressant action in male mice

Fig. 4

a–c Schematic diagram (a), representative images showing the expression of SSTGFP neurons (b) and the axon projection targets of HBXSST neurons (c) (n = 3 mice). d–f Schematic diagram (d), representative images (e, n = 3 mice), and a plot (f) showing the axon projection targets of HBXSST neurons and c-fos anti-body staining is utilized to identify the activation of neurons within the IPN. Data are presented as mean ± SEM (n = 3 mice per group, **p = 3.78 × 10−4, two-tailed t-test). g–k SST neurons project excitatory synapses onto PENK neurons. Schematic diagram (g) and representative images showing the expression of ChR2-GFP in SST neuronal axon terminals (h, n = 3 mice) and tdT in PENK neurons. Whole-cell patch-clamp recordings from PENK neurons were validated by biocytin labeling through recording electrodes (i, n = 4 mice). The evoked EPSCs by optogenetic stimulation of axon terminals of SSTChR2GFP neurons were completely blocked by 20 μM CNQX (j) or 1 μM TTX and reversed by 4-AP (k). Data are presented as mean ± SEM (n = 10 neurons from 7 mice, ***p = 3.96 × 10−11 in (j), ACSF vs. TTX ***p = 2.68 × 10-9 in (k), TTX vs. TTX/4-AP ***p = 1.75 × 10-6 in (k), paired sample two-tailed t-test for (j), one-way repeated measures ANOVA for (k), ns, no significant difference). l–o SST neurons receive inhibitory synaptic inputs from CCK neurons. Schematic diagram (l) and representative images showing the expression of TVA/G and GFP in SST neurons (m, n = 3 mice) and GFP in CCK neurons (n, n = 3 mice). The evoked IPSCs (o) recorded from SST neurons were completely blocked by 20 μM BIC or 1 μM TTX (also see Supplementary Fig. 11). Data are presented as mean ± SEM (n = 10 neurons from 6 mice, ACSF vs. TTX ***p = 5.07 × 10−12, ACSF vs. BIC ***p = 5.01 × 10−10, paired sample two-tailed t-test). VTA: ventral tegmental area; IPN: interpeduncular nucleus; PENK: proenkephalin; ACSF: artificial cerebrospinal fluid; CNQX: 6-cyano-7-nitroquinoxaline-2,3-dione; TTX: tetrodotoxin; 4-AP: 4-amino phenylacetic acid; BNST: bed nucleus of the stria terminalis; BIC: bicuculline. Source data are provided as a Source Data file.

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