Figure 2
Experimental timelines for tract-tracer iontophoretic injections and hormone replacements. (a) Timeline and cartoon of a sagittal hemisection of the rat brain representing animals that underwent an injection of fluorogold (FLG) into the ventral tegmental area (VTA) (n=15). (b) Timeline and cartoon of a sagittal hemisection of the rat brain representing animals that received injections of FLG in the nucleus accumbens (NAc) and biotinylated dextran amine (BDA) in the medial preoptic area (mPOA) and hormone replacement (n=6). Colocalization of sex-steroid hormone receptors in the rostral and central mPOA cells that project to the VTA is depicted in (c) and (d). (c) Colocalization of FLG-positive cells with NeuN, estrogen receptor-α (ERα), progesterone receptor (PR), and G-protein estrogen receptor (GPER). Values are expressed as mean±SEM. ***p<0.001. (d) Representative photomicrographs of colocalization of NeuN (red) or sex-steroid hormone receptors (green) and FLG (blue) in the mPOA. Arrows point to cells demonstrating colocalization (scale bar is 50 μm). mPOA efferents to the VTA appose dopaminergic cell bodies, which then project to the NAc is evidenced in panels e and g. (e) A representative photomicrograph of placement of BDA, an anterograde tract-tracer, in the mPOA (scale bar is 500 μm). (f) A representative photomicrograph of FLG placement, a retrograde tract-tracer, in the shell of the nucleus accumbens (scale bar is 500 μm). (g) A pie chart describing the percentage of all cells sampled in the VTA apposed or not apposed by BDA-positive processes. (h) Representative photomicrographs of coronal sections of the VTA containing FLG (blue), TH (red), and BDA (green). Arrows represent points of apposition. Scale bars, 200 and 20 μm from left to right. AC, anterior commisure; BDA, biotinylated dextran amine; LV, lateral ventricle; OX, optic chiasm; TH, tyrosine hydroxylase; 3V, third ventricle.
