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Non associative learning processes studies in swimming behavior of the leech Hirudo medicinalis
No full textCyclic AMP mediates the inhibition of the Na+/K+ electrogenic pump by serotonin in t sensory neurones of the leech
No full textOctopamine and Leydig cell stimulation depress the after-hyperpolarization in T sensory neurons of the leech
No full textIn touch sensory neurons of the leech, a train of spikes evoked by intracellular electrical stimulation leads to an afterhyperpolarization, mainly due to the activation of the Na+/K+ electrogenic pump and partly to a Ca’+ -activated K+ conductance. It has been found that serotonin is able to reduce
the afterhyperpolarization through the inhibition of the Na+/K+ electrogenic pump. We have investigated the possible modulation of the afterhyperpolarization by other endogenous neurotransmitters and we have found that octopamine is also able to reduce its amplitude. The electrical stimulation of the octopaminergic Leydig neurons mimics this effect. We have compared the actions of the two amines and found that
the effect of serotonin is blocked by methysergide but not by high [Mg2+] or by phentolamine, and it is still present in touch cells isolated in culture. On the contrary, the octopamine modulation of the afterhyperpolarization does not occur in single touch cells in culture and it is blocked by all these treatments.
These data suggest that while serotonin should act monosynaptically, octopamine should act through
a serotonergic pathway
Serotonin depresses the after-hyperpolarization through the inhibition of the Na+/K+ electrogenic pump in T sensory neurones of the leech
No full textIn T sensory neurones of the leech, a train of impulses elicited by intracellular electrical stimulation leads to an after-hyperpolarization of up to 30 mV, mainly due to the activation of the electrogenic Na+/K+-ATPase but partly to a Ca2+-activated K+ conductance. It was found that serotonin reversibly reduced the amplitude of this after-hyperpolarization. We investigated the mechanism of action of serotonin and found: (1) after inhibition of the Ca2+-activated K+ conductance with BaCl2 or CdCl2, serotonin was still able to reduce the after-hyperpolarization; (2) when penetration of T cells with microelectrodes leaking sodium was preceded by serotonin perfusion of the ganglia, the normal hyper-polarization due to the activation of the electrogenic pump was converted to a depolarization; (3) after long-lasting perfusion with K+-free saline solution (which inhibits the Na+/K+ pump), the application of CsCl caused repolarization by reactivating the electrogenic ATPase; serotonin slowed and reduced this repolariz-ation; (4) serotonin potentiated the depolarization of T neurones caused by the inhibition of the Na + /K + pump following cooling of ganglia and depressed the hyperpolarization after rewarming to room temperature. These data taken together suggest that serotonin directly inhibits the Na+/K+ electrogenic pump
Chiesa e centro parrocchiale "Gesù Maestro"- Potenza
No full textLa pubblicazione raccoglie i contributi relativi al 10° Convegno” Identità dell’Architettura Italiana” che si è svolto Il 5 ed il 6 dicembre 2012 a Firenze. Il convegno è stato organizzato dalla Facoltà di Architettura, Dipartimento di Architettura – Disegno, Storia, Progetto – Dottorato di ricerca in Architettura/Progettazione architettonica e Urbana di Firenze, con il patrocinio del Comune di Firenze, dell’Istituto degli Innocenti e della rivista “Casabella”. Il contributo dell’autore, a partire dalla descrizione del progetto per il centro parrocchiale Gesù Maestro, racconta alcuni concetti propri del suo fare architettura.The publication collects the contributions related to the 10th Conference "Identity of Italian Architecture" which took place on the 5th and 6th December 2012 in Florence. The conference was organized by the Faculty of Architecture, Department of Architecture - Design, History, Project - PhD in Architecture / Architectural and Urban Design of Florence, with the patronage of the City of Florence, the Institute of Innocents and the magazine " Nice house". The author's contribution, starting from the description of the project for the parish center Gesù Maestro, tells some of the concepts of his architecture
Seasonal variation of serotonin content and nonassociative learning of swim induction in the leech Hirudo medicinalis.
No full textIt is possible to obtain habituation of swim induction by stimulating the leech with repetitive light electrical trains. After obtaining this simple form of non-associative learning, it is also possible to potentiate its response by a series of nociceptive skin brushings (dishabituation). Serotonin applied to the animal is the only neurotransmitter found to mimick dishabituation. We have observed that in the period April-June most animals did not exhibit potentiation of the swimming response after nociceptive stimulation while injection of serotonin mimicked dishabituation as in the animals treated in the period October-March. We have seen correlation between the changes in nonassociative learning and the seasonal variation of serotonin levels in segmental ganglia. This finding strengthens the hypothesis of serotonin as the neurotransmitter mediating dishabituation in swim induction of the leech
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