“…The most striking findings in the development of the two systems relative to one another are in the raphé obscurus in which there is an increase in GABA Aα3 expression and decrease in GABA Aα1 expression over the same time-period, suggesting a dynamic period in the GABAergic development in a site heavily concentrated with 5-HT neurons. The raphé obscurus is implicated in respiratory control (Feldman et al, 2006; Pierrefiche et al, 1998; Shao et al, 1997), carbon dioxide chemosensitivity (Curran et al, 2000; Curran et al, 2001; Nattie, 1999; Nattie, 1991), heart rate and blood pressure regulation (Dampney, 1994; Heesch et al, 2006; Menezes et al, 2007), baroreflexes (Callera et al, 2000; Callera et al, 2005), temperature control (Darnall et al, 2001; Darnall et al, 2006), and pain (Stamford, 1995). Our studies suggest that the development of 5-HT markers is “static” in the raphé obscurus from birth into infancy, yet changes continue to occur in GABA A receptor subunits; thus, potential developmental changes in 5-HT-mediated function in the raphé obscurus after birth may reflect, at least in part, changes in GABA modulation.…”