Fig. 7: OMP-KO nerves show rapid adaptation in response to repetitive stimulation.

a Experimental setup of an in vivo multiunit recording from the nerve layer of the olfactory epithelium using a recording pipette inserted through a hole in the left nasal bone (a yellow dot). Odours were applied through a puffer pipette inserted into the left nostril (a green dot). b A 5-mL plastic tube containing scented filter paper or food as an odour application chamber was interconnected between a pressure pump and a puffer. c An approximately 0.2-psi air puff was applied from the puffer pipette into the nostril. Repetitive air puffs with 100-ms durations followed by 300-ms intervals at 20 psi were applied for 20 s. ϕ: diameters. d Multiunit responses from the nerve bundle layer of WT mice show sustained increases in firing during stimulation. e Multiunit responses from the nerve bundle layer of KO mice show a decrease during stimulation. f, g Representative histograms of spike amplitudes before (PRE) and during (STIM) odour-puff stimulation for 20 s in (f) WT mice and (g) KO mice. h Relative changes in the collective firing frequencies during nasal air-puff stimulation with L( + ) or food (Fd) or without odours (Air) to the resting frequencies (PRE) in (h) WT, Het and KO mice. Means: black bars. *P < 0.05; **P < 0.01; ***P < 0.001. Statistics: h one-way ANOVA and the post hoc Bonferroni multiple-comparison test. L( + ); F(3, 13) = 23.06, P < 0.001 and P_{WT vs Het} > 0.999, P_{WT vs KO} = 0.0001, P_{Het vs KO} = 0.0003. n = 5, 5 and 6 for WT, Het and KO. Food; F(3, 9) = 6.602, P = 0.017 and P_{WT vs Het} > 0.999, P_{WT vs KO} = 0.076 and P_{Het vs KO} = 0.021. # means P_{WT vs KO} = 0.045 in the post hoc Dunnett test. n = 4 each for WT, Het and KO. Air; F(3, 12) = 41.08, P < 0.0001 and P_{WT vs Het} = 0.32, P_{WT vs KO} < 0.0001 and P_{Het vs KO} < 0.0001. n = 5 each for WT, Het and KO.