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. 2021 Sep 29;10:e66609. doi: 10.7554/eLife.66609

Figure 1. Magnocellular AVP neurons receive excitatory and inhibitory input from the LT.

Figure 1.

(a, e) Schematic of monosynaptic rabies tracing from magnocellular PVHAVP (a) and SONAVP (e) neurons. To target magnocellular PVHAVP neurons, rabies virus was injected into the posterior pituitary. (b, f) Representative images showing magnocellular PVHAVP (b) and SONAVP (f) starter neurons as identified by co-expression of GFP and mCherry. (c, g), Representative images showing magnocellular PVHAVP (c) and SONAVP (g) starter neurons and dense rabies labeling in the SON (c) and PVH (g). (d, h) Representative images showing sites containing rabies-labeled neurons in the LT that are monosynaptically connected to magnocellular PVHAVP (d) and SONAVP (h) neurons. (i) Schematic of anterograde tracing from excitatory and inhibitory neurons in the SFO and MnPO/OVLT. (j) Representative images showing expression of Syn-YFP in excitatory and inhibitory neurons in the SFO and MnPO/OVLT (left box), and their efferent projections in the SFO, MnPO, OVLT, PVH, and SON (right box). Note lack of YFP-labeled fibers from SFOVgat neurons in the PVH and SON. (k) Schematic of CRACM (top) and representative images showing co-localization of GFP and AVP immunofluorescence (red) in the PVH (middle) and SON (bottom ) of AVP-GFP mice. (l, m) Number of PVHAVP and SONAVP neurons (l) and non-GFP PVH and SON neurons (m) receiving direct synaptic inputs from MnPO/OVLTVglut2, SFOVglut2, and MnPO/OVLTVgat neurons as identified by CRACM. Mice used include AVP-GFP;Vglut2-IRES-Cre (MnPO/OVLTVglut2 and SFOVglut2) and AVP-GFP;Vgat-IRES-Cre (MnPO/OVLTVgat). Scale bar, 200 µm. (n) Representative traces showing light-evoked responses in SFOVglut2 to SONAVP (left), MnPO/OVLTVglut2 to SONAVP (middle), and MnPO/OVLTVgat to SONAVP (right) CRACM. Black trace is an average of all traces (gray) in consecutive trials. AVP, vasopressin; CRACM, channelrhodopsin (ChR2)-assisted circuit mapping; LT, lamina terminalis; MnPO, median preoptic nucleus; OVLT, organum vasculosum lamina terminalis; PVH, paraventricular; SFO, subfornical organ; SON, supraoptic nuclei.