Role of serotonin and cyclic AMP on facilitation of the fast conducting system activity in the leechHirudo Medicinalis

Belardetti, Francesco; Biondi, Carla; Colombaioni, Laura; Brunelli, Marcello; Trevisani, Agostino

doi:10.1016/0006-8993(82)90145-7

Cited by 54 publications

(25 citation statements)

References 26 publications

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“…Exogenous serotonin or serotonergic neuron stimulation enhances S-cell excitability in the same manner as sensitization (Burrell et al, 2001). Serotonin also increases the S-cell response to mechanosensory stimuli (Belardetti et al, 1982;Burrell et al, 2002). The S-cell involvement in activating serotonergic neurons during sensitization and its subsequent enhancement in excitability by serotonin may explain why both serotonin depletion (Ehrlich et al, 1992) and lesions of the S-cell chain (Sahley et al, 1994;Modney et al, 1997) produce similar disruption of sensitization.…”

Section: Roles Of the S-cell In Sensitizationmentioning

confidence: 92%

Progressive recovery of learning during regeneration of a single synapse in the medicinal leech

Burrell

Sahley

Muller

2003

J of Comparative Neurology

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The leech escape reflex-shortening of the body-can change with nonassociative conditioning, including sensitization, habituation, and dishabituation. Capacity for sensitization, which is an enhancement of the reflex, is lost when a single S-interneuron is ablated, but the reflex response itself remains. In the present experiments, the S-interneuron's axon in the living leech was filled with 6-carboxyfluorescein (6-CF) dye and cut with an argon laser microbeam (lambda = 488 nm). In contrast to sham-operated animals, axotomized preparations did not sensitize, reflecting the key role of the S-cell. By 2 weeks or more, S-cell axons had regenerated and reestablished synapses at their usual locations with neighboring S-cells. By 4 weeks, this restored the ability to sensitize to a level indistinguishable from that of controls, but an intermediate state of recovery was seen from 2-3 weeks after injury-a period not previously examined. The small capacity for sensitization among newly regenerated preparations was significantly lower than in sham controls but appeared higher than in animals whose cut S-cell axon had not regenerated its synapse. The results confirm the crucial role of the S-cell in sensitization. Moreover, full sensitization does not occur immediately upon synapse regeneration.

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Section: Roles Of the S-cell In Sensitizationmentioning

confidence: 92%

Progressive recovery of learning during regeneration of a single synapse in the medicinal leech

Burrell

Sahley

Muller

2003

J of Comparative Neurology

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“…It is known that cyclic AMP supports phenomena of neuronal plasticity and simple forms of learning in invertebrates (Brunelli, Castellucci & Kandel, 1976;Belardetti et al 1982;Kandel & Schwartz, 1982;Brunelli, Demontis & Traina, 1985;Brunelli, Colombaioni, Demontis & Traina, 1986). In Hirudo medicinalis cyclic AMP has been shown to play a role in mediating both 5-HT and dopamine action Pareschi et al 1987) as well as protein phosphorylation (Garcia-Gil et al 1989a; Garcia-Gil, Berton, Tongiorgi & Brunelli, 1989b).…”

Section: Discussionmentioning

confidence: 99%

Cyclic AMP mediates inhibition of the Na(+)‐K+ electrogenic pump by serotonin in tactile sensory neurones of the leech.

Catarsi

Scuri

Brunelli

1993

The Journal of Physiology

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SUMMARY1. Serotonin (5-HT) reduced the after-hyperpolarization (AHP) amplitude in tactile sensory neurones (T) but not in pressor (P) or nociceptive (N) cells of the leech.2. Adenylate cyclase activators, phosphodiesterase inhibitors and membrane permeant analogues of cyclic adenosine monophosphate (cyclic AMP) mimicked the effect of 5-HT in reducing the AHP amplitude in T neurones.3. lonophoretic injection of cyclic AMP in T cells reduced the AHP amplitude, while cyclic guanosine monophosphate (cyclic GMP) or adenosine-5'-monophosphate (AMP) were without effect.4. Inhibition of adenylate cyclase by the drug RMI 12330A (also known as MDL 12330A) suggested that 5-HT reduced the AHP amplitude through cyclic AMP.5. 8-Bromoadenosine-3'-5'-cyclic monophosphate (8-Br-cyclic AMP) was still able to reduce the AHP amplitude after blocking the Ca2+-activated K+ conductance with CdCl2 and converted the normal hyperpolarization which follows the intracellular injection of Na+ into a depolarization. In addition, the cyclic AMP analogue slowed down and reduced the repolarization usually induced by CsCl after perfusion with K+-free solution.It is proposed that, in T sensory neurones, cyclic AMP mediates the inhibition of the Na+-K+ electrogenic pump induced by 5-HT application.

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“…Indeed, ganglia of hungry and well-fed leeches have different levels of 5-HT (Lent et al, 1991). The action of 5-HT in the central nervous system has been assigned to modulating membrane currents in identified neurons (Acosta-Urquidi et al, 1989;Lessmann and Dietzel, 1995b;Ali et al, 1998), electrical coupling between neurons (Belardetti et al, 1982;Beck et al, 2002), and the afterhyperpolarization in sensory neurons via a cAMP-mediated pathway (Catarsi and Brunelli, 1991;Catarsi et al, 1993). In the periphery, 5-HT regulates mucus secretion (Lent, 1973) and muscle tone (Mason and Kristan, 1982).…”

Section: Introductionmentioning

confidence: 98%

5‐Hydroxytryptamine activates a barium‐sensitive, cAMP‐mediated potassium conductance in the leech giant glial cell

Britz

Hirth

Schneider

et al. 2004

Glia

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5-Hydroxytryptamine (5-HT), a neurotransmitter and neuromodulator in the central nervous system of the leech Hirudo medicinalis hyperpolarizes the giant glial cell in the neuropil of segmental ganglia at micromolar concentrations. The 5-HT-evoked glial response (EC(50) approximately 2.5 microM) is mediated by a non-desensitizing, G-protein-coupled receptor and due to activation of a Ca(2+)-independent K(+) conductance. The adenylyl cyclase inhibitor SQ22,536 blocks the response to 5-HT; in the presence of 1 mM db-cAMP, but not of 1 mM db-cGMP, the glial response is suppressed. The 5-HT-evoked response is reduced by Ba(2+) with half-maximal inhibition at 50 microM Ba(2+). The results suggest that release of 5-HT from serotonergic neurons, or the maintenance of micromolar levels of extracellular 5-HT in the ganglion, may help to set the glial membrane potential close to the K(+) equilibrium potential.

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Role of serotonin and cyclic AMP on facilitation of the fast conducting system activity in the leechHirudo Medicinalis

Cited by 54 publications

References 26 publications

Progressive recovery of learning during regeneration of a single synapse in the medicinal leech

Progressive recovery of learning during regeneration of a single synapse in the medicinal leech

Cyclic AMP mediates inhibition of the Na(+)‐K+ electrogenic pump by serotonin in tactile sensory neurones of the leech.

5‐Hydroxytryptamine activates a barium‐sensitive, cAMP‐mediated potassium conductance in the leech giant glial cell

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