Ca2+ dynamics in synaptosomes isolated from the squid optic lobe

Benech, Juan Claudio; Lima, Pedro U.; Sotelo, Julio; Brown, Euan R.

doi:10.1002/1097-4547(20001215)62:6<840::aid-jnr11>3.0.co;2-8

Cited by 9 publications

(9 citation statements)

References 48 publications

(43 reference statements)

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“…Calcium-induced calcium release from internal stores has also been reported from squid ORNs [22]. We assume lobster ORNs may also have internal calcium stores since bath application of ionomycin during fura-2 calibration induced a significant elevation in Ca i under extracellular Ca-free conditions [23, 24]. Lobster ORNs are also known to generate IP 3 which targets IP 3 receptor channels on the plasma membrane of the olfactory dendrite [25].…”

Section: Discussionmentioning

confidence: 99%

Imaging ensemble activity in arthropod olfactory receptor neurons in situ

2011

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We show that lobster olfactory receptor neurons (ORNs), much like their vertebrate counterparts, generate a transient elevation of intracellular calcium (Ca i ) in response to odorant activation that can be used to monitor ensemble ORN activity. This is done in antennal slice preparation in situ maintaining the polarity of the cells and the normal micro-environment of the olfactory ilia. The Ca i signal is ligand-specific and increases in a dose-dependent manner in response to odorant stimulation. Saturating stimulation elicits a robust increase of up to 1 μM free Ca i within 1-2 sec of stimulation. The odor-induced Cai response closely follows the discharge pattern of extracellular spikes elicited by odorant application, with the maximal rise in Ca i matching the peak of the spike generation. The Ca i signal can be used to track neuronal activity in a functional subpopulation of rhythmically active ORNs and discriminate it from that of neighboring tonically active ORNs. Being able to record from many ORNs simultaneously over an extended period of time not only allows more accurate estimates of neuronal population activity but also dramatically improves the ability to identify potential new functional subpopulations of ORNs, especially those with more subtle differences in responsiveness, ligand specificity, and/or transduction mechanisms.

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Section: Discussionmentioning

confidence: 99%

Imaging ensemble activity in arthropod olfactory receptor neurons in situ

2011

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“…With the use of intracellular and extracellular Ca 2ϩ ionophores, chelators, and other modulators, protein synthesis of optic lobe synaptosomes was shown to proceed at nearly optimal rates when the intraterminal Ca 2ϩ level was maintained within the normal physiological range. When this level increased or decreased, protein synthesis was markedly depressed (26,27,57). As strong inhibition was also induced by calphostin, a selective inhibitor of protein kinase C (26), modulation of presynaptic protein synthesis by Ca 2ϩ may be in large part funneled through protein kinase C (PKC) and its downstream targets, eIF-2 or eEF-2.…”

Section: Squid Nerve Endingsmentioning

confidence: 99%

Local Gene Expression in Axons and Nerve Endings: The Glia-Neuron Unit

Giuditta¹,

Chun²,

Eyman³

et al. 2008

Physiological Reviews

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Neurons have complex and often extensively elongated processes. This unique cell morphology raises the problem of how remote neuronal territories are replenished with proteins. For a long time, axonal and presynaptic proteins were thought to be exclusively synthesized in the cell body, which delivered them to peripheral sites by axoplasmic transport. Despite this early belief, protein has been shown to be synthesized in axons and nerve terminals, substantially alleviating the trophic burden of the perikaryon. This observation raised the question of the cellular origin of the peripheral RNAs involved in protein synthesis. The synthesis of these RNAs was initially attributed to the neuron soma almost by default. However, experimental data and theoretical considerations support the alternative view that axonal and presynaptic RNAs are also transcribed in the flanking glial cells and transferred to the axon domain of mature neurons. Altogether, these data suggest that axons and nerve terminals are served by a distinct gene expression system largely independent of the neuron cell body. Such a local system would allow the neuron periphery to respond promptly to environmental stimuli. This view has the theoretical merit of extending to axons and nerve terminals the marginalized concept of a glial supply of RNA (and protein) to the neuron cell body. Most long-term plastic changes requiring de novo gene expression occur in these domains, notably in presynaptic endings, despite their intrinsic lack of transcriptional capacity. This review enlightens novel perspectives on the biology and pathobiology of the neuron by critically reviewing these issues.

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“…Benech et al (17) found that changing the external K ϩ concentration from 10 to 30 mmol l -1 KCl evoked a transient increase in cytoplasmic Ca 2ϩ in synaptosomes isolated from squid optic lobe. The Ca 2ϩ transient in that study was calculated to be around 340 nmol l -1 and reached its maximal level in less than 10 s, which seems to be consisent with the typical behavior of voltage-gated Ca 2ϩ channels that inactivate rapidly.…”

Section: ⅐Mgmentioning

confidence: 99%

Acetylcholine Release and Choline Uptake by Cuttlefish (Sepia officinalis) Optic Lobe Synaptosomes

Nunes

Santos

Cordeiro

et al. 2008

The Biological Bulletin

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Acetylcholine (ACh), which is synthesized from choline (Ch), is believed to hold a central place in signaling mechanisms within the central nervous system (CNS) of cuttlefish (Sepia officinalis) and other coleoid cephalopods. Although the main elements required for cholinergic functionCuttlefish, like other coleoid cephalopods, has been the subject of many neurobiological studies. Although the functional anatomy of the cuttlefish nervous system has been well illustrated, including investigation by electrical stimulation (1, 2), much less information is available on signaling mechanisms within the neural networks of cephalopods (3).The CNS of cuttlefish consists of distinct but interconnected lobes, of which the paired optic lobes correspond to more than half (4). The cuttlefish optic lobe comprises an outer granule cell layer, a neurophil layer, an inner granule cell layer (the outer cortex), and numerous clusters of cell bodies separated by areas of nerve fibers and synaptic areas (the central medulla) (5). The optic lobes contain a repertoire of neuronal circuits, which integrate the central visual processing, visuomotor, learning and memory systems (6). ACh has been suggested to mediate neuronal signaling at the CNS of cuttlefish, given that the Koelle-Friedenwald stain revealed a neuropilar localization of the reaction of cholinesterases (7). Moreover, it has been shown that ACh catabolism increases in the optic lobes as a response to memory formation with a long-term retention delay (8). Additionally, the optic lobes, in which nicotinic-like receptors are widely present (9), are among the cuttlefish CNS regions with the highest levels of enzyme activity responsible for the synthesis (choline acetyltransferase) and degradation (acetylcholinesterase) of ACh (10). Furthermore, recent work on cuttlefish optic lobe slices (11) has shown that mecamylamine hydrochloride, a nicotinic receptor antagonist, blocks excitatory postsynaptic currents, which are due to spontaneously released ACh. As far as we know, our recent paper (12) was the first to provide a brief insight into the release of ACh and the uptake of its precursor (Ch) in cuttlefish optic lobe. The present study further characterizes

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Ca2+ dynamics in synaptosomes isolated from the squid optic lobe

Cited by 9 publications

References 48 publications

Imaging ensemble activity in arthropod olfactory receptor neurons in situ

Imaging ensemble activity in arthropod olfactory receptor neurons in situ

Local Gene Expression in Axons and Nerve Endings: The Glia-Neuron Unit

Acetylcholine Release and Choline Uptake by Cuttlefish (Sepia officinalis) Optic Lobe Synaptosomes

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