Figure 7.
Orexinergic and other PeF/LH neurons influence BAT thermogenesis. (A) Coronal brain section through the PeF/LH shows many double-labeled (white arrowheads, yellow fluorescence in the cytoplasm) orexinergic (red) neurons that were pseudorabies virus (PRV)-infected (green), indicating their synaptic connection to BAT. Modified, with permission, from (386). (B) Orexinergic fibers (red) surround putative BAT sympathetic premotor neurons in rRPa (and in PaPy) transsynaptically infected following PRV inoculations of interscapular BAT. Modified, with permission, from (386). (C) Under cool conditions (Tcore < 37°C) with a low level of basal BAT, nanoinjection of orexin-A (Orx-A, dashed line) in the rRPa elicited prolonged increases in BAT, Tbat, Exp CO2, and heart rate (HR). Modified, with permission, from (386). (D) Under cool conditions (Tcore < 37°C) with a low level of basal BAT, nanoinjection of NMDA (dashed line) in the PeF/LH elicited prolonged increases in BAT, Tbat, Exp CO2, and HR. Modified, with permission, from (386). (E) icv PGE2 (filled symbols), but not ACSF (open symbols), elicited a marked increase in BAT temperature in orexin-KO mice (triangles) and in the wild-type littermates for either the orexin-KO (circles) and for the orexin neuron-ablated (squares) mice, but had no effect on Tbat in orexin neuron-ablated mice (diamonds). Modified, with permission, from (372). (F) The activation of BAT and BAT thermogenesis produced by disinhibitory activation of PeF/LH neurons with bicuculline (BIC) nanoinjection is dependent on the activation of glutamate receptors on DMH/DA neurons. Modified, with permission, from (55).