Iodoacetate inhibits the biosynthesis of alanine in glial cells and its utilization in photoreceptors of the honeybee drone (Apis mellifera) retina

Saravelos, S. G.; Tsacopoulos, M.

doi:10.1007/bf00387304

Cited by 3 publications

(4 citation statements)

References 17 publications

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“…The presence of CHH and TPH immunoreactivity in pigmented accessory retinal cells, such as the tapetal cells, and the increasing evidence that the reflecting pigment is only a part of this cell's function, whose main functions seem to provide metabolic support to retinular cells (Meyer-Rochow, 1999) as proven in insects (Saravelos and Tsacopoulos, 1995), open new per- spectives for the crayfish retina studies. On the one hand, data from our laboratory suggest that isolated retinal and optic lobe cells pooled from juvenile and adult P. clarkii secrete CHH (Escamilla-Chimal et al, 2002).…”

Section: Neurochemical Experimentsmentioning

confidence: 97%

The circadian system of crayfish: A developmental approach

Fanjul‐Moles

Prieto-Sagredo

2003

Microscopy Res & Technique

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Adult crayfish exhibit a variety of overt circadian rhythms. However, the physiological mechanisms underlying the overt rhythms are controversial. Research has centered on two overt rhythms: the motor activity and the retinal sensitivity rhythms of the genus Procambarus. The present work reviews various studies undertaken to localize pacemakers and mechanisms of entrainment responsible for these two rhythms in adult organisms of this crustacean decapod. It also describes an ontogenetic approach to the problem by means of behavioral, electrophysiological, and neurochemical experiments. The results of this approach confirm previous models proposed for adult crayfish, based on a number of circadian pacemakers distributed in the central nervous system. However, the coupling of rhythmicity between these independent oscillators might be complex and dependent on the interaction between serotonin (5-HT), light, and the crustacean hyperglycemic hormone (CHH). The latter compound has, up until now, not been considered as an agent in the genesis and synchronization of the retinal sensitivity rhythm.

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Section: Neurochemical Experimentsmentioning

confidence: 97%

The circadian system of crayfish: A developmental approach

Fanjul‐Moles

Prieto-Sagredo

2003

Microscopy Res & Technique

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“…By contrast with FL, the action of IAA in the central nervous system is reported not only in mammals (Segal and Boyer, 1953;Webb, 1966;Kitano et al, 2003) but also in insects (Brazitikos and Tsacopoulos, 1991;Saravelos and Tsacopoulos, 1995). Iodoacetate is an inhibitor of glycolysis (Saravelos and Tsacopoulos, 1995), affecting the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (Segal and Boyer, 1953), and also enzymes of the Krebs cycle (Webb, 1966). IAA action on the lamina cells was probably more complex than that of FL, changing not only pH but also cell metabolism because 10-mM concentration was lethal for flies, and changes in L1 and L2 sizes were not offset, like in the case of FL, by changes in glia sizes.…”

Section: The Action Of Gliotoxinsmentioning

confidence: 99%

“…Its action has been studied in mammals (Noell, 1952;Schurr et al, 1988;Kitano et al, 2003) as well as in insects (Brazitikos and Tsacopoulos, 1991;Saravelos and Tsacopoulos, 1995). In the retina of the honey bee drone IAA decreases oxygen consumption and the receptor potential in light-activated compound eye photoreceptors (Saravelos and Tsacopoulos, 1995). Both toxins, FL and IAA, inhibit the metabolism of glial cells first and thereby kill the neighboring neurons.…”

Section: Introductionmentioning

confidence: 99%

Involvement of glial cells in rhythmic size changes in neurons of the housefly's visual system

Pyza

Górska-Andrzejak

2004

J. Neurobiol.

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In the housefly's first optic neuropile, or lamina, the axons of two classes of monopolar cell interneurons, L1 and L2, exhibit a daily rhythm of size changes: swelling during the day, and shrinking by night. At least for the L2 cells this rhythm is circadian. Moreover, epithelial glial cells that enwrap each lamina cartridge, its monopolar cell axons, and their surrounding crown of input photoreceptor terminals also change size, but in the opposite direction to the changes in L1 and L2-swelling by night and shrinking by day. The rhythmic changes in glia indicate the possible involvement of these cells in the lamina's circadian system. To examine their role in regulating the rhythmic changes of L1 and L2's axon sizes we have injected three chemicals into the haemolymph of the fly's head: fluorocitrate (FL) and iodoacetate (IAA), which affect the metabolism of glial cells, and octanol (OC), which closes gap junction channels. All chemicals exerted an effect on L1 and L2, which depended on the time of injection, the drug concentration, and the postinjection times at which we examined the fly's brains. Moreover, day/night changes in the axon sizes of L1 and L2 were increased in FL- and IAA-treated flies, indicating that glial cells may normally inhibit these changes by regulating the sizes of L1 and L2's axons during the day and night. In turn, lack of a day/night rhythm in L1 and L2 after OC injections shows that the rhythm's persistence depends on communication between the lamina cells through gap junction channels.

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“…To look for effects of alanine and other candidate substrates on the oxidative metabolism of the photoreceptors, it was necessary first to reduce the supply from the glia. Saravelos & Tsacopoulos (1995) reported that the classical inhibitor of glycolysis, iodoacetate, is unusable for this experiment because it also inhibits photoreceptor metabolism. We found that 1,4‐dideoxy‐1,4‐imino‐ d ‐arabinitol (DAB), an inhibitor of glycogen phosphorylase (Andersen et al 1999), appears to reversibly reduce the supply of substrates from the glia without affecting the ability of the photoreceptors to use exogenous substrates.…”

mentioning

confidence: 99%

A glia–neuron alanine/ammonium shuttle is central to energy metabolism in bee retina

Coles

Martiel²,

Laskowska

2008

The Journal of Physiology

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It has been proposed that glial cells may supply carbon fuel to neurons and also that there are fluxes of ammonium from neurons to glia. We have investigated both these proposals in Apis retinal slices, in which virtually all the mitochondria are in the photoreceptor neurons. Normally the superfusate contained no substrate of energy metabolism; addition of glucose or alanine did not increase oxygen consumption (Q O 2 ), confirming that the neurons received adequate substrate from glycogen in the glia. + ] e in 0 Cl − . These results strengthen the evidence that in superfused retinal slices, glucose is metabolized exclusively in the glia, which supply alanine to the neurons, and that ammonium returns to the glia. They also show that another fuel (perhaps lactate) can be supplied by the glia to the neurons.

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Iodoacetate inhibits the biosynthesis of alanine in glial cells and its utilization in photoreceptors of the honeybee drone (Apis mellifera) retina

Cited by 3 publications

References 17 publications

The circadian system of crayfish: A developmental approach

The circadian system of crayfish: A developmental approach

Involvement of glial cells in rhythmic size changes in neurons of the housefly's visual system

A glia–neuron alanine/ammonium shuttle is central to energy metabolism in bee retina

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