Figure 5

Circadian and dark pulse regulation of orexin-A and non-orexin-A neuronal activation in the tuberal hypothalamus. c-Fos expression (A) and c-Fos co-expression in OXA neurons (C) are increased in the medial TH by a dark pulse (DP1; onset indicated by the left vertical broken line at DP1 arrowhead, while the 6 h duration of DP1 is shown as the filled horizontal bar top left) beginning at CT5, while after 1 h exposure to a 6 h dark pulse (DP2; beginning at the right broken vertical line and arrowhead at CT16 with the 6 h duration, depicted by the filed horizontal bar top right) suppresses c-Fos and c-Fos/OXA co-expression. In the lateral TH c-Fos expression is not altered by the subjective day dark pulse (B), but co-expression of c-Fos with OXA neurons is elevated 1 h and 4 h into the pulse (D). By contrast, c-Fos expression in the subjective night in the lateral TH is suppressed within 2 h (B); co-expression of c-Fos with OXA was unaffected. Histograms show mean ± SEM. **p < 0.01, *p < 0.05.