, 2008), and analyzed CTGF expression 4, 8, 12, and 20 days postinjection (Figure 6H). Ablation of olfactory receptor neurons was confirmed by impairment in food search of olfactotoxin-injected mice

(Figures S6A and S6B) and by decreased expression of the olfactory marker protein (OMP) (Figures S6C and S6D). Suppression of the sensory input led to a significant decrease in CTGF expression already 4 days postinjection, and at 12 days postinjection CTGF expression was barely detectable (Figure 6I and Figure S6E for quantification). CTGF expression was partially restored 20 days postinjection, correlating with partial reinnervation of olfactory sensory input as reported (Alonso et al., 2008). Decreased CTGF expression levels following olfactotoxin treatment did not result from a demise of external tufted cells (i.e., CTGF-expressing cells), as was evidenced by an unchanged number of CCK-positive cells (data not shown). Conversely, Cabozantinib concentration TGF-β2 expression was strongly elevated during the period of olfactory input impairment and reached a maximum 8 days

postinjection (Figure 6J). Ctgf is an immediate-early gene with a short half-life ( Kroening et al., 2009) and is thus suited to test whether environmental changes at a fast timescale alter CTGF expression levels. The first indication for the activity-dependent regulation of CTGF expression derives from its coexpression with c-fos, another activity-dependent immediate-early gene ( Figure S6F). Since suppression of olfactory input resulted in a reduction of CTGF expression, we hypothesized that olfactory enrichment augments CTGF expression. Mice were presented daily selleck chemical Cell press with three distinct odors for three weeks (63 distinct odorants in total) ( Figure S6G), and CTGF expression levels were evaluated thereafter in 200 glomeruli ( Figures S6H and S6I). Glomeruli were subdivided according to their intensity of CTGF expression into four categories: very high (>10 units), high (5–10 units), intermediate (1–5 units), and low (0–1 units) (for details, see the Supplemental

Experimental Procedures). There was no difference in CTGF expression levels between controls and mice subjected to an odor-enriched environment ( Figure S6J). This is not too surprising, as one would expect to see a potential augmentation of the short-lived CTGF only in few glomeruli that were activated by the last few odorants. We also measured whether the enrichment paradigm resulted in changes of neuronal survival in the glomerular layer (see BrdU treatment rationale in Figure S6G) and found no difference in BrdU-positive cell number between control and odor-enriched mice ( Figure S6K). To investigate the possible activity dependence of CTGF expression in specific glomeruli, we employed transgenic mice, namely MOR23-IRES-tauGFP, in which only two glomeruli per OB are EGFP labeled and hence can be surveyed over time (Vassalli et al., 2002).