The actions of L-glutamate and its agonists on the ampullary electroreceptor organs of the catfish Ictalurus nebulosus

Spontaneous nerve activity and sensitivity in catfish ampullary electroreceptor organs after tetanus toxin application

“…The autorelease hypothesis can explain the findings of Andrianov et al [5] mentioned in the introduction. Application of magnesium to the electroreceptors blocks sensitivity as well as the spontaneous activity.…”

“…Such a depolarization of the cells could be the result of a so-called bias current [8,9], which has indeed been shown to exist in similar sensory systems. Also Andrianov et al [5] showed that the spontaneous activity can be completely abolished by applying 30 mM Mg 2+ . Because Mg 2+ is known to block synaptic transmission, he argued that the spontaneous spike activity is the result of the presynaptic processes [5].…”

“…Also Andrianov et al [5] showed that the spontaneous activity can be completely abolished by applying 30 mM Mg 2+ . Because Mg 2+ is known to block synaptic transmission, he argued that the spontaneous spike activity is the result of the presynaptic processes [5]. These experiments support the hypothesis that the depolarization necessary to maintain the spontaneous activity originates in the receptor cells.…”

“…The resulting rise in Ca 2+ concentration induces neurotransmitter release at the synapse. The neurotransmitter in this synapse is identified as glutamate [3,4,5,6,7]. The release of glutamate evokes excitatory postsynaptic potentials in the afferent nerve.…”

The role of defensins in the excitability of the peripheral vestibular system in the frog: Evidence for the presence of communication between the immune and nervous systems

“…At the same time, there is good reason to believe that the role of defensins in the living organisms is more wide ranging, and that these natural antibiotics influence physiological processes such as neurotransmission. Hair cells are the first candidates for this role because of their chemicallymediated synapses which exhibit a very high efficacy of both neurotransmitters and neuromodulators (Annoni et al, 1984;Andrianov et al, 1992;Prigioni and Russo, 1995;Guth et al, 1998a;Ryzhova, 1999, 2000;Andrianov et al, 2005). These compounds may act on membrane receptors located on the hair cells or afferent nerve fibres and thus they can alter the properties of postsynaptic receptors and the responsiveness of afferent fibres.…”