Effect of the neurotoxin MPTP on hypothalamic A11 neurons.

<p><b>A.</b> Representative microphotograph of TH-IR A11 neurons in a control animal. <b>B.</b> Representative microphotograph of TH-IR A11 neurons in an MPTP-intoxicated animal with full parkinsonism. Note the large cell loss within the A11 area. <b>C.</b> Mean (±SD) percentage of total number of TH-IR neurons remaining following MPTP intoxication within the substantia nigra, ventral tegmental area and A11 group (*<i>P</i><0.0005, comparison between MPTP-treated animals (n = 2) and control animals (n = 4); ^#<i>P</i><0.02 and ^###<i>P</i><0.0003, comparison between dopaminergic groups following MPTP intoxication, two-tailed <i>P</i> value, unpaired <i>t</i>-test). Note the difference in cell loss following MPTP intoxication between the A11 group and the various DA regions. <b>D.</b> TH-IR counted cells were mapped in individual sections from anterior to posterior hypothalamic A11 area with 200 µm section intervals. Note the general cell loss at different levels of the A11 area in MPTP-treated animals (n = 2) compared to controls (n = 4). <b>E–J</b>: Representative micrograph of TH (green) and CALB (red) double fluorescent immunostaining obtained under a confocal laser-scanning microscope in VTA (<b>E–G</b>) and A11 (<b>H–J</b>) sections. The white arrows point to typical double-stained neurons. Note the absence of CALB-positive neurons within the A11 region. Abbreviations: Calb = Calbindin 28 k; TH = Tyrosine Hydroxylase; V3 = Third Ventricle.