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The bite of the honeybee: 2-heptanone secreted from honeybee mandibles during a bite acts as a local anaesthetic in insects and mammals.

Papachristoforou A, Kagiava A, Papaefthimiou C, Termentzi A, Fokialakis N, Skaltsounis AL, Watkins M, Arnold G, Theophilidis G - PLoS ONE (2012)

Bottom Line: We compared the inhibitory effects of 2-H and lidocaine on voltage-gated sodium channels.Using the same method, we showed that 2-H has the fastest inhibitory effect of all alkyl-ketones tested, including the isomers 3- and 4-heptanone.Our results reveal a previously unknown role of 2-H in honeybee defensive behaviour and due to its minor neurotoxicity show potential for developing a new local anaesthetic from a natural product, which could be used in human and veterinary medicine.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Animal Physiology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece. papachri@legs.cnrs-gif.fr

ABSTRACT
Honeybees secrete 2-heptanone (2-H) from their mandibular glands when they bite. Researchers have identified several possible functions: 2-H could act as an alarm pheromone to recruit guards and soldiers, it could act as a chemical marker, or it could have some other function. The actual role of 2-H in honeybee behaviour remains unresolved. In this study, we show that 2-H acts as an anaesthetic in small arthropods, such as wax moth larva (WML) and Varroa mites, which are paralysed after a honeybee bite. We demonstrated that honeybee mandibles can penetrate the cuticle of WML, introducing less than one nanolitre of 2-H into the WML open circulatory system and causing instantaneous anaesthetization that lasts for a few minutes. The first indication that 2-H acts as a local anaesthetic was that its effect on larval response, inhibition and recovery is very similar to that of lidocaine. We compared the inhibitory effects of 2-H and lidocaine on voltage-gated sodium channels. Although both compounds blocked the hNav1.6 and hNav1.2 channels, lidocaine was slightly more effective, 2.82 times, on hNav.6. In contrast, when the two compounds were tested using an ex vivo preparation-the isolated rat sciatic nerve-the function of the two compounds was so similar that we were able to definitively classify 2-H as a local anaesthetic. Using the same method, we showed that 2-H has the fastest inhibitory effect of all alkyl-ketones tested, including the isomers 3- and 4-heptanone. This suggests that natural selection may have favoured 2-H over other, similar compounds because of the associated fitness advantages it confers. Our results reveal a previously unknown role of 2-H in honeybee defensive behaviour and due to its minor neurotoxicity show potential for developing a new local anaesthetic from a natural product, which could be used in human and veterinary medicine.

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The effect of 2-heptanone on hNav1.2 (a) and hNav1.6 (b) sodium channels. Data represent tonic (a and c) and phasic (b and d) effects. Solid curves represent when data are fitted with a logistic equation with minimum and maximum effects fixed at 0 and 100% (n = 6).
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pone-0047432-g004: The effect of 2-heptanone on hNav1.2 (a) and hNav1.6 (b) sodium channels. Data represent tonic (a and c) and phasic (b and d) effects. Solid curves represent when data are fitted with a logistic equation with minimum and maximum effects fixed at 0 and 100% (n = 6).

Mentions: To test whether 2-H can also act by blocking VGNaCs, we used the PatchXpress 7000A to expose mammalian CHO (Chinese hamster ovary) cells transfected with hNav1.2 and hNav1.6 channels to various concentrations of both 2-H and lidocaine. For 2-H, the inward current generated by the depolarization of the cells was recorded within the first 3 min of exposure to eliminate problems created by the high volatility (see Materials and Methods) We plotted the concentration-response curves for 2-H versus hNav1.2 and hNav1.6 channels under tonic and phasic conditions (Fig. 4 a, b, c, d) and estimated the IC50 values (concentration required to inhibit function to 50% of normal sodium current) (Table 1). Also, it was possible to estimate the IC50 values for lidocaine from similar curves, against the same ionic channels (Table 1). The results shown in Table 1 indicate a discrepancy between the local anaesthetic effect of 2-H and that of lidocaine in the phasic experiments. In the phasic experiments, 2-H was 7.5 times less active than lidocaine for hNav1.2 and hNav1.6. In contrast, in the tonic experiments, 2-H was 3.97 times less active than lidocaine for hNav1.2 and only 2.82 times less active for hNav1.6–a channel located on the nodal region of the nerve fibres [18].


The bite of the honeybee: 2-heptanone secreted from honeybee mandibles during a bite acts as a local anaesthetic in insects and mammals.

Papachristoforou A, Kagiava A, Papaefthimiou C, Termentzi A, Fokialakis N, Skaltsounis AL, Watkins M, Arnold G, Theophilidis G - PLoS ONE (2012)

The effect of 2-heptanone on hNav1.2 (a) and hNav1.6 (b) sodium channels. Data represent tonic (a and c) and phasic (b and d) effects. Solid curves represent when data are fitted with a logistic equation with minimum and maximum effects fixed at 0 and 100% (n = 6).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3472974&req=5

pone-0047432-g004: The effect of 2-heptanone on hNav1.2 (a) and hNav1.6 (b) sodium channels. Data represent tonic (a and c) and phasic (b and d) effects. Solid curves represent when data are fitted with a logistic equation with minimum and maximum effects fixed at 0 and 100% (n = 6).
Mentions: To test whether 2-H can also act by blocking VGNaCs, we used the PatchXpress 7000A to expose mammalian CHO (Chinese hamster ovary) cells transfected with hNav1.2 and hNav1.6 channels to various concentrations of both 2-H and lidocaine. For 2-H, the inward current generated by the depolarization of the cells was recorded within the first 3 min of exposure to eliminate problems created by the high volatility (see Materials and Methods) We plotted the concentration-response curves for 2-H versus hNav1.2 and hNav1.6 channels under tonic and phasic conditions (Fig. 4 a, b, c, d) and estimated the IC50 values (concentration required to inhibit function to 50% of normal sodium current) (Table 1). Also, it was possible to estimate the IC50 values for lidocaine from similar curves, against the same ionic channels (Table 1). The results shown in Table 1 indicate a discrepancy between the local anaesthetic effect of 2-H and that of lidocaine in the phasic experiments. In the phasic experiments, 2-H was 7.5 times less active than lidocaine for hNav1.2 and hNav1.6. In contrast, in the tonic experiments, 2-H was 3.97 times less active than lidocaine for hNav1.2 and only 2.82 times less active for hNav1.6–a channel located on the nodal region of the nerve fibres [18].

Bottom Line: We compared the inhibitory effects of 2-H and lidocaine on voltage-gated sodium channels.Using the same method, we showed that 2-H has the fastest inhibitory effect of all alkyl-ketones tested, including the isomers 3- and 4-heptanone.Our results reveal a previously unknown role of 2-H in honeybee defensive behaviour and due to its minor neurotoxicity show potential for developing a new local anaesthetic from a natural product, which could be used in human and veterinary medicine.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Animal Physiology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece. papachri@legs.cnrs-gif.fr

ABSTRACT
Honeybees secrete 2-heptanone (2-H) from their mandibular glands when they bite. Researchers have identified several possible functions: 2-H could act as an alarm pheromone to recruit guards and soldiers, it could act as a chemical marker, or it could have some other function. The actual role of 2-H in honeybee behaviour remains unresolved. In this study, we show that 2-H acts as an anaesthetic in small arthropods, such as wax moth larva (WML) and Varroa mites, which are paralysed after a honeybee bite. We demonstrated that honeybee mandibles can penetrate the cuticle of WML, introducing less than one nanolitre of 2-H into the WML open circulatory system and causing instantaneous anaesthetization that lasts for a few minutes. The first indication that 2-H acts as a local anaesthetic was that its effect on larval response, inhibition and recovery is very similar to that of lidocaine. We compared the inhibitory effects of 2-H and lidocaine on voltage-gated sodium channels. Although both compounds blocked the hNav1.6 and hNav1.2 channels, lidocaine was slightly more effective, 2.82 times, on hNav.6. In contrast, when the two compounds were tested using an ex vivo preparation-the isolated rat sciatic nerve-the function of the two compounds was so similar that we were able to definitively classify 2-H as a local anaesthetic. Using the same method, we showed that 2-H has the fastest inhibitory effect of all alkyl-ketones tested, including the isomers 3- and 4-heptanone. This suggests that natural selection may have favoured 2-H over other, similar compounds because of the associated fitness advantages it confers. Our results reveal a previously unknown role of 2-H in honeybee defensive behaviour and due to its minor neurotoxicity show potential for developing a new local anaesthetic from a natural product, which could be used in human and veterinary medicine.

Show MeSH
Related in: MedlinePlus