78 research outputs found
Dietary yeast influences ethanol sedation in Drosophila via serotonergic neuron function
Abuse of alcohol is a major clinical problem with far- reaching health consequences. Understanding the environmental and genetic factors that contribute to alcohol- related behaviors is a potential gateway for developing novel therapeutic approaches for patients that abuse the drug. To this end, we have used Drosophila melanogaster as a model to investigate the effect of diet, an environmental factor, on ethanol sedation. Providing flies with diets high in yeast, a routinely used component of fly media, increased their resistance to ethanol sedation. The yeast- induced resistance to ethanol sedation occurred in several different genetic backgrounds, was observed in males and females, was elicited by yeast from different sources, was readily reversible, and was associated with increased nutrient intake as well as decreased internal ethanol levels. Inhibition of serotonergic neuron function using multiple independent genetic manipulations blocked the effect of yeast supplementation on ethanol sedation, nutrient intake, and internal ethanol levels. Our results demonstrate that yeast is a critical dietary component that influences ethanol sedation in flies and that serotonergic signaling is required for the effect of dietary yeast on nutrient intake, ethanol uptake/elimination, and ethanol sedation. Our studies establish the fly as a model for diet- induced changes in ethanol sedation and raise the possibility that serotonin might mediate the effect of diet on alcohol- related behavior in other species.Flies fed a high yeast diet consume more nutrients, have decreased levels of internal ethanol when exposed to ethanol vapor and require longer exposure to ethanol to become sedated (ie, increased ST50). Our studies implicate serotonergic neurons as key regulators of nutrient consumption and therefore, the effect of dietary yeast on ethanol sedation in flies.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155987/1/adb12779.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155987/2/adb12779_am.pd
Cocaine Increases Dopamine Release by Mobilization of a Synapsin-Dependent Reserve Pool
Cocaine primarily exerts its behavioral effects by enhancing dopaminergic neurotransmission, amplifying dopamine-encoded sensorimotor integration. The presumed mechanism for this effect is inhibition of the dopamine transporter, which blocks dopamine uptake and prolongs the duration of dopamine in the extracellular space. However, there is growing evidence that cocaine can also augment dopamine release. Here, we directly monitored the actions of cocaine on dopamine release by using electrochemical detection to measure extracellular dopamine in the striatum of anesthetized mice. Cocaine enhanced the levels of striatal dopamine produced by electrical stimulation of dopaminergic neurons. Even after pretreatment with alpha-methyl-p-tyrosine, which depletes the readily releasable pool of dopamine, cocaine was still capable of elevating dopamine levels. This suggests that cocaine enhances dopamine release by mobilizing a reserve pool of dopamine-containing synaptic vesicles. To test this hypothesis, we examined electrically evoked dopamine release in synapsin I/II/III triple knock-out mice, which have impaired synaptic vesicle reserve pools. Knock-out of synapsins greatly reduced the ability of cocaine to enhance dopamine release with long stimulus trains or after depletion of the newly synthesized pool. We therefore conclude that cocaine enhances dopamine release and does so by mobilizing a synapsin-dependent reserve pool of dopamine-containing synaptic vesicles. This capacity to enhance exocytotic release of dopamine may be important for the psychostimulant actions of cocaine
Data from: Early changes in transient adenosine during cerebral ischemia and reperfusion injury
Adenosine is an important neuromodulator in the central nervous system, and tissue adenosine levels increase during ischemic events, attenuating excitotoxic neuronal injury. Recently, our lab developed an electrochemical fast-scan cyclic voltammetry (FSCV) method that identified rapid, spontaneous changes in adenosine concentrations that last only about 3 seconds. Here, we investigated the effects of cerebral ischemia and reperfusion on the concentration and frequency of transient adenosine release in the caudate-putamen. In anesthetized rats, data were collected for four hours: two hours of normoxia, 30 min of cerebral ischemia induced by bilateral common carotid artery occlusion, and 90 min of reperfusion. Transient adenosine release was increased during the cerebral ischemia period and remained elevated during reperfusion. The total number of adenosine transients increased by 52% during cerebral ischemia and reperfusion compared to normoxia. The concentration of adenosine per event did not increase but the cumulative adenosine concentration during cerebral ischemia and reperfusion increased by 53% because of the higher frequency of events. Further, we evaluated the role of A2A antagonist, SCH442416, a putative neuroprotective agent to affect adenosine transients. SCH442416 significantly decreased the transient frequency during cerebral ischemia-reperfusion by 27% and the cumulative concentration by 31%. Our results demonstrate that this mode of rapid adenosine release increases during early cerebral ischemia-reperfusion injury. Rapid adenosine release could provide fast, local neuromodulation and neuroprotection during cerebral ischemia
Early changes in transient adenosine during cerebral ischemia and reperfusion injury.
Adenosine is an important neuromodulator in the central nervous system, and tissue adenosine levels increase during ischemic events, attenuating excitotoxic neuronal injury. Recently, our lab developed an electrochemical fast-scan cyclic voltammetry (FSCV) method that identified rapid, spontaneous changes in adenosine concentrations that last only about 3 seconds. Here, we investigated the effects of cerebral ischemia and reperfusion on the concentration and frequency of transient adenosine release in the caudate-putamen. In anesthetized rats, data were collected for four hours: two hours of normoxia, 30 min of cerebral ischemia induced by bilateral common carotid artery occlusion, and 90 min of reperfusion. Transient adenosine release was increased during the cerebral ischemia period and remained elevated during reperfusion. The total number of adenosine transients increased by 52% during cerebral ischemia and reperfusion compared to normoxia. The concentration of adenosine per event did not increase but the cumulative adenosine concentration during cerebral ischemia and reperfusion increased by 53% because of the higher frequency of events. Further, we evaluated the role of A2A antagonist, SCH442416, a putative neuroprotective agent to affect adenosine transients. SCH442416 significantly decreased the transient frequency during cerebral ischemia-reperfusion by 27% and the cumulative concentration by 31%. Our results demonstrate that this mode of rapid adenosine release increases during early cerebral ischemia-reperfusion injury. Rapid adenosine release could provide fast, local neuromodulation and neuroprotection during cerebral ischemia
Fast-scan Cyclic Voltammetry for the Characterization of Rapid Adenosine Release
Adenosine is a signaling molecule and downstream product of ATP that acts as a neuromodulator. Adenosine regulates physiological processes, such as neurotransmission and blood flow, on a time scale of minutes to hours. Recent developments in electrochemical techniques, including fast-scan cyclic voltammetry (FSCV), have allowed direct detection of adenosine with sub-second temporal resolution. FSCV studies have revealed a novel mode of rapid signaling that lasts only a few seconds. This rapid release of adenosine can be evoked by electrical or mechanical stimulations or it can be observed spontaneously without stimulation. Adenosine signaling on this time scale is activity dependent; however, the mode of release is not fully understood. Rapid adenosine release modulates oxygen levels and evoked dopamine release, indicating that adenosine may have a rapid modulatory role. In this review, we outline how FSCV can be used to detect adenosine release, compare FSCV with other techniques used to measure adenosine, and present an overview of adenosine signaling that has been characterized using FSCV. These studies point to a rapid mode of adenosine modulation, whose mechanism and function will continue to be characterized in the future
Transient Adenosine Modulates Serotonin Release Indirectly in the Dorsal Raphe Nuclei
Rapid adenosine transiently
regulates dopamine and glutamate via
A1 receptors, but other neurotransmitters, such as serotonin,
have not been studied. In this study, we examined the rapid modulatory
effect of adenosine on serotonin release in the dorsal raphe nuclei
(DRN) of mouse brain slices by using fast-scan cyclic voltammetry.
To mimic adenosine release during damage, a rapid microinjection of
adenosine at 50 pmol was applied before electrical stimulation of
serotonin release. Transient adenosine significantly reduced electrically
evoked serotonin release in the first 20 s after application, but
serotonin release recovered to baseline as adenosine was cleared from
the slice. The continuous perfusion of adenosine did not change the
evoked serotonin release. Surprisingly, the modulatory effects of
adenosine were not regulated by A1 receptors as adenosine
still inhibited serotonin release in A1KO mice and also
after perfusion of an A1 antagonist (8-cyclopentyl-1,3-dipropyl
xanthine). The inhibition was also not regulated by A3 receptors
as perfusion of the A3 antagonist (MRS 1220) in A1KO brain slices did not eliminate the inhibitory effects of transient
adenosine. In addition, adenosine also inhibited serotonin release
in A2AKO mice, showing that A2A did not modulate
serotonin. However, perfusion of a selective 5HT1A autoreceptor
antagonist drug [(S)-WAY 100135 dihydrochloride] abolished the inhibitory
effect of transient adenosine on serotonin release. Thus, the transient
neuromodulatory effect of adenosine on DRN serotonin release is regulated
by serotonin autoreceptors and not by adenosine receptors. Rapid,
transient adenosine modulation of neurotransmitters such as serotonin
may have important implications for diseases such as depression and
brain injury
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