Figure 7.

DAMGO significantly increases the percentage of Fos-expressing orexin neurons in selective areas of the hypothalamus. Top, Numbers of neurons expressing c-Fos after intra-accumbens DAMGO or saline injection and orexin-immunoreactive neurons in two areas of the hypothalamus (see Fig. 6). Middle, Numbers of Fos-IR neurons expressing orexin immunoreactivity (double-labeled) and non-orexin neurons expressing Fos immunoreactivity. Bottom, Double-labeled neurons expressed as percentage of orexin-IR and Fos-IR neurons. Note that the number and percentage of orexin-IR neurons expressing DAMGO-induced c-Fos (double-labeled neurons) is significantly higher compared with saline (*p < 0.05) only in the area dorsomedial to the fornix.