Figure 4

Increased mucus secretion induces shorter duration responses but does not affect onset time.

(a) Experimental protocol for pilocarpine injection. (b) Physical responses (nasal discharge, saliva, and soft stool) to different pilocarpine concentrations (0.2, 0.1, and 0.05 mg/kg). +++, prominent; ++, intermediate; +, mild. (c) A representative photomicrograph of the OE stained for olfactory marker protein (OMP) in a pilocarpine-treated mouse. Scale bar, 20 μm. (d) Comparison of the number of OMP-positive cells between pilocarpine- and saline-injected mice. (e) Response ratio (magnitude after vs. before pilocarpine administration) at each concentration. Clear neural responses are detected only at 0.05 mg/kg (in seven of nine mice), whereas no responses are detected after the administration of high pilocarpine concentrations (0.2 and 0.1 mg/kg, two mice per dose group). (f) Comparison of peak amplitude between before and after pilocarpine administration. (g) Image of the OB dorsal surface before pilocarpine administration. g1–g3 are individual glomeruli. Scale bar, 500 μm. (h) PST-induced spH signals from individual glomeruli (g1–g3) before pilocarpine administration. Magenta open rectangle, onset latency; magenta filled rectangle, duration. (i) Image of the OB dorsal surface after pilocarpine administration. g1–g3 as in (e). Scale bar, 500 μm. (j) PST-induced spH signals from individual glomeruli (g1–g3) after pilocarpine administration. Yellow open rectangle, onset latency; yellow filled rectangle, duration. (k) Summary of onset latency and duration for each glomerulus shown in (g,i). Diamond, onset latency; square, duration. (l,m) Comparison of onset latency (l) and duration (m) before and after pilocarpine administration. OB, olfactory bulb. (n,o) Comparison of respiration (resp., n) and heart rate (h.r., o) before and after pilocarpine administration. Each recording includes the period of pre- (pre) and post-response (post). Statistical comparisons were done using Mann-Whitney U-test (d,f,l,m) and two-way ANOVA (n,o). n.s., no significant difference. *p < 0.05. All values are mean ± SD.