Fig. 2. Respiratory and cellular c-Fos responses to CO₂ challenge.

a, b Represents bar graphs of the no. of sighs at baseline and during infusion of 7.5%CO₂ (normoxic). c Line graph represents the respiratory rate responses (breaths/min) for wildtype, SERT^+/− and SER^−/− rats during atmospheric air infusions (non-shaded regions) and during hypercapnic gas (7.5% CO₂, normoxic air, shaded region) infusions. Asterisks(*) indicates significant between subjects effects with a Fishers LSD posthoc test protected by an ANOVA, and hastag(#) indicates significant within subject time effects with a Dunnett’s test protected by a repeated measures one way ANOVA. d, e bar graph represents ex vivo cellular responses (evidenced by numbers of cells with nuclear expression of c-Fos protein immunostaining) in the dorsomedial hypothalamic nucleus (DMN), dorsolateral periaqueductal gray (DLPAG) and amygdala nuclei following exposure to 7.5%CO2 in wildtype, SERT^+/− and SERT^−/− rats. Error bars represent the SEM