INVESTIGADORES
MARIN BURGIN Antonia
artículos
Título:
BASAL ACETYLCHOLINE RELEASE IN LEECH GANGLIA DEPOLARIZES
Autor/es:
ANTONIA MARIN-BURGIN; LIDIA SZCZUPAK
Revista:
JOURNAL OF EXPERIMENTAL BIOLOGY
Editorial:
Thc Company Biologist Limited
Referencias:
Lugar: Great Britain; Año: 1998 vol. 201 p. 1907 - 1915
ISSN:
0022-0949
Resumen:
The response of Retzius neurons, the main neuronal
source of serotonin in the leech nervous system, to
cholinergic agonists has been extensively investigated. In
this study, we analyzed the effects of inhibiting the
acetylcholinesterase (AChE) activity in the leech midbody
ganglion on the electrophysiological activity of the Retzius
neurons. Bath application of neostigmine and
physostigmine (0.1100 mmol l-1) produced, after a delay, a
strong depolarization of the Retzius neurons with a dosedependent
amplitude and latency. The amplitude of this
depolarization increased as the extracellular level of Ca2+2+
increased and decreased as the extracellular level of Ca2+2+
decreased. The response to neostigmine and physostigmine
was inhibited by curare (100 mmol l-1), nicotine
(10 mmol l-1), atropine (100 mmol l-1) and strychnine
(100 mmol l-1), but was not affected by mecamylamine
(100 mmol l-1) or hexamethonium (100mmol l-1).
Superfusion with solutions containing 100 mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1) produced, after a delay, a
strong depolarization of the Retzius neurons with a dosedependent
amplitude and latency. The amplitude of this
depolarization increased as the extracellular level of Ca2+2+
increased and decreased as the extracellular level of Ca2+2+
decreased. The response to neostigmine and physostigmine
was inhibited by curare (100 mmol l-1), nicotine
(10 mmol l-1), atropine (100 mmol l-1) and strychnine
(100 mmol l-1), but was not affected by mecamylamine
(100 mmol l-1) or hexamethonium (100mmol l-1).
Superfusion with solutions containing 100 mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1), nicotine
(10 mmol l-1), atropine (100 mmol l-1) and strychnine
(100 mmol l-1), but was not affected by mecamylamine
(100 mmol l-1) or hexamethonium (100mmol l-1).
Superfusion with solutions containing 100 mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1), atropine (100 mmol l-1) and strychnine
(100 mmol l-1), but was not affected by mecamylamine
(100 mmol l-1) or hexamethonium (100mmol l-1).
Superfusion with solutions containing 100 mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1), but was not affected by mecamylamine
(100 mmol l-1) or hexamethonium (100mmol l-1).
Superfusion with solutions containing 100 mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1) or hexamethonium (100mmol l-1).
Superfusion with solutions containing 100 mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1
strychnine or atropine produced a progressive
hyperpolarization of the Retzius neurons, while
superfusion with 100 mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.mmol l-1 curare did not. The
hyperpolarization induced by atropine was inhibited in the
presence of curare. Other neurons in the ganglion showed
distinctive responses to the AChE inhibitors that were
coincident with their responses to cholinergic agonists.
The results suggest the existence of a basal level of
acetylcholine (ACh) release in the leech ganglion that is
powerfully counteracted by endogenous AChE activity.
Under control conditions, this basal release appears to be
sufficient to generate an ACh tonus that regulates the
membrane potential of Retzius neurons. Since these neurons
can support a sustained firing rate, which is dependent on
the membrane potential, the results presented in this report
suggest that the basal ACh tonus regulates the output of
these neuromodulatory serotonergic neurons.