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First published online December 22, 2003
Journal of Experimental Biology 207, 411-416 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00778
Stimulation of the
-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca
1 Laboratório de Farmacologia, Instituto Butantan, Av. Vital Brazil,
1500, 05503-900, São Paulo, Brazil
2 Laboratório de Biologia Celular, Instituto Butantan, Av. Vital
Brazil, 1500, 05503-900, São Paulo, Brazil
3 Departamento de Fisiologia, Instituto de Biociências, Universidade
de São Paulo, Rua do Matão, travessa 14, 05508-900 São
Paulo, Brazil
* Author for correspondence (e-mail: norma{at}butantan.gov.br)
Accepted 30 October 2003
The noradrenergic innervation of Bothrops jararaca venom gland is
thought to be important in the production and secretion of venom. We
investigated the characteristics of the
-adrenoceptor in the venom
gland and its role in venom production. This receptor had relatively low
sensitivity to noradrenaline (pD2=4.77±0.09, N=7)
and to phenylephrine (pD2=3.77±0.06, N=11). The
receptor became desensitized just after venom extraction (pD2 to
phenylephrine fell to 3.27±0.02, N=6) and the sensitivity
remained low for at least 15 days, returning to normal 30 days after venom
extraction, by which time the snake was ready for a new cycle of venom
production. Incubation of secretory cells with noradrenaline
(104 mol l1 for 5 min) reduced
-adrenoceptor sensitivity to the level seen after venom extraction.
Blockade of catecholamine production with reserpine abolished the enlargement
of the rough endoplasmic reticulum and the activation of the Golgi apparatus
that are normally seen after venom extraction, and the venom production was
restored by a single subcutaneous (s.c.) injection of phenylephrine (100 mg
kg1) immediately after venom extraction. Our data suggest
that stimulation of the
-adrenoceptor during or shortly after biting is
essential for the onset of the venom production cycle.
Key words:
-adrenoceptor, desensitization, venom production, venom gland, Bothrops jararaca, snake
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