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First published online December 22, 2003
Journal of Experimental Biology 207, 387 (2004)
Copyright © 2004 The Company of Biologists Limited
doi: 10.1242/jeb.00804
Inside JEB |
NORADRENALINE TRIGGERS VIPER'S VENOM
kathryn{at}biologists.com
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Most vipers don't waste their venom on any old mouthful. It takes time and energy to produce a gland-full of venom, so profligacy isn't an option. But just what triggers toxin synthesis wasn't clear until Norma Yamanouye and her colleagues began testing the response of Bothrops jararaca's venom glands to noradrenaline. The venom gland's adrenoceptor became desensitised to noradrenaline after venom was extracted from the snake, but after a month the receptor had regained its sensitivity. So once venom production was triggered, it didn't seem possible to stimulate the adrenoceptor again until the gland was recharged with venom 30 days later (p. 411).
But was noradrenaline triggering the toxin's synthetic cycle? Yamanouye
tested the gland's toxin-secreting cells by first depleting the gland's own
noradrenaline and then giving the cells a dose of phenylephrine, to stimulate
the adrenoceptor and see whether the stimulated cells began producing venom.
While the team watched, the cells appearance changed, in preparation for
making the snake's venomous protein `suggesting that stimulation of the
-adrenoceptor during or shortly after biting is essential for the onset
of the venom production cycle' says Yamanouye.
References
Kerchove, C. M., Carneiro, S. M., Markus, R. P. and Yamanouye,
N. (2004). Stimulation of the -adrenoceptor triggers
the venom production cycle in the venom gland of Bothrops jararaca.J. Exp. Biol. 207,411
-416.
Related articles in JEB:
-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca
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