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. 2016 Jul 22;11(7):e0158868. doi: 10.1371/journal.pone.0158868

Fig 4. Borneol evoked tear secretion without nociceptive effect in guinea pigs.

Fig 4

(A) RT-PCR of TRPM8 mRNA expressed in the cornea of guinea pig. N.C., negative control. (B) 100 μM borneol and menthol were applied to the ocular surface at 25 and 35°C to induce tear production (** P<0.01, *** P<0.001 vs vehicle at the same temperature; ## P<0.01, ### P<0.001 between groups indicated; n = 10 in each group). (C) TRPM8 channel blockers AMTB (10 μM) and BCTC (20 μM) inhibited borneol- and menthol-induced tear production (*** P<0.001 vs control; n = 10 in each group). (D) Total time spent for eye wiping with paws by the animals within 5 min after the drop of 100 μM borneol and menthol solution to the corneas. No significantly difference was observed between groups (n = 4 in each group).