Drosophila Activity Monitoring System Research Articles

A male-killing Spiroplasma endosymbiont has age-mediated impacts on Drosophila endurance and sleep

Endosymbiotic bacteria have a wide range of impacts on host physiology, behavior, metabolism, endurance, and mobility. Recent work found some endosymbionts also impact host sleep duration and quality. These effects may increase as flies age and endosymbiont titers increase. We tested the hypothesis that Spiroplasma poulsonni MSRO negatively impacts sleep in Drosophila melanogaster, and this in turn impairs fly endurance. In geotaxis climbing assays (a proxy for endurance), we found that MSRO impacted climbing endurance but in an age-dependent manner. Among younger flies, MSRO+ flies slept significantly less during dark periods (measured by a Drosophila Activity Monitoring System) compared to uninfected flies, but older MSRO+ flies did not show significant differences in amount of sleep compared to uninfected flies in the same cohort. While MSRO status impacted both sleep and endurance of hosts, endosymbiont-mediated sleep deprivation did not directly explain decreases in fly endurance. We discuss these results in the context of endosymbiont comparative biology.

Abstract P1013: Identification Of Genetic Links Between Cardiovascular Disease And Insomnia In Drosophila

Cardiovascular disease (CVD) is the leading cause of death worldwide. CVD is associated with insomnia such that insomnia symptoms double the risk of incident CVD. However, how they are related is unknown. Two recent genome-wide association studies (GWAS) identified genetic loci significantly associated with insomnia, including one locus with five nearby genes that are associated with CVD in an independent GWAS. Therefore, we hypothesized that genetic predisposition to insomnia contributes to the development of CVD. To test this and identify causal genes at this locus, we used Drosophila melanogaster, which are well-established model systems for sleep and cardiac studies. To assess the role of these genes on cardiac physiology, we used the cardiac-specific Hand-Gal4 driver to perform genetic knockdown (KD). One-week-old Drosophila progeny were then used for semi-intact microscopic heart preparation followed by high-speed videography to assess cardiac physiology. Similarly, to assess their role in sleep, we used the neuronal-specific Elav-Gal4 driver to perform KD of these genes. Sleep and locomotor activity of one-week-old flies were monitored using the Drosophila Activity Monitoring System. We found that neuronal and cardiac-specific RNAi KD of four genes conserved in Drosophila: Lsn, ATPSynC, Bruce, and Imp, contributes to compromised sleep and cardiac performance, respectively. Cardiac-specific KD of Lsn led to significant cardiac dilation and reduced fractional shortening, a measure of cardiac performance. KD of ATPSynC led to significantly reduced fractional shortening without dilations. Furthermore, Lsn and ATPSynC KD hearts had disrupted actin-containing myofibrillar organization. Suppression of Lsn increased Pericardin deposition, indicative of fibrosis. Also, the cardiac suppression of ATPSynC and Lsn significantly shortened lifespan. Neuronal-specific KD of three genes significantly disrupted sleep. Furthermore, KD of ATPSynC and Lsn in the heart disrupted sleep in a non-cell-autonomous manner. This work provides novel insights into genetic mechanisms linking CVD and insomnia, highlighting the potential importance of these four genes in the development of both diseases.

Alterations in the activity and sleep of Drosophila melanogaster under simulated microgravity

This study aimed to investigate alterations in the activity and sleep of Drosophila melanogaster under simulated microgravity, which was implemented through the random positioning machine, while different light conditions (normal photoperiod and constant dark) were set. Fruit flies of different strains and sexes were treated for 3 days, and activity and sleep were monitored using the Drosophila Activity Monitoring System. After 3 days of treatment, fruit flies were sampled to detect the relative expression levels of the major clock genes and some neurotransmitter-related genes. The results showed that for the normal photoperiod (LD) condition, the activity increased and sleep decreased under simulated microgravity, while for the constant dark (DD) condition, the activity and sleep rhythms appeared disordered and the activity increased, thus decreasing the likelihood of waking up during the day. Light conditions, strains, and sexes, individually or in combination, had impacts on the simulated microgravity effects on behaviors. The clock genes and neurotransmitter-related genes had different degrees of response among sexes and strains, although the overall changes were slight. The results indicated that the normal photoperiod could ease the effects of simulated microgravity on fruit flies’ activity and sleep and possible unidentified pathways involved in the regulatory mechanism need further exploration. This study is expected to provide ideas and references for studying the effects of microgravity on space life science.

Simulated mobile communication frequencies (3.5 GHz) emitted by a signal generator affects the sleep of Drosophila melanogaster

With the rapid development of science and technology, 5G technology will be widely used, and biosafety concerns about the effects of 5G radiofrequency radiation on health have been raised. Drosophila melanogaster was selected as the model organism for our study, in which a 3.5 GHz radiofrequency radiation (RF-EMR) environment was simulated at intensities of 0.1 W/m2, 1 W/m2, and 10 W/m2. The activity of parent male and offspring (F1) male flies was measured using a Drosophila activity monitoring system under short-term and long-term 3.5 GHz RF-EMR exposure. Core genes associated with heat stress, the circadian clock and neurotransmitters were detected by QRT-PCR technology, and the contents of GABA and glutamate were detected by UPLC-MS. The results show that short-term RF-EMR exposure increased the activity level and reduced the sleep duration while long-term RF-EMR exposure reduced the activity level and increased the sleep duration of F1 male flies. Under long-term RF-EMR, the expression of heat stress response-related hsp22, hsp26 and hsp70 genes was increased, the expression of circadian clock-related per, cyc, clk, cry, and tim genes was altered, the content of GABA and glutamate was reduced, and the expression levels of synthesis, transport and receptor genes were altered. In conclusion, long-term RF-EMR exposure enhances the heat stress response of offspring flies and then affects the expression of circadian clock and neurotransmitter genes, which leads to decreased activity, prolonged sleep duration, and improved sleep quality.

Sexual Dimorphism of Behavioral Response to Dopamine Modulation in Drosophila

IntroductionDespite considerable evidence that women are more vulnerable to addiction than men, biomedical research has been performed almost exclusively in males, and the results assumed to apply equally to men and women. Recent NIH policy regarding inclusion of sex as a biological variable is contributing to more proportional evaluation and greater translational value of future publications, but the current body of literature contains very little regarding sex differences in Drosophila melanogaster response to psychostimulants. While studying the contributions of the serotonergic system on psychostimulant response in Drosophila using DREADD technology and the Drosophila Activity Monitoring System (DAMS), we found sexually dimorphic behavioral responses to methamphetamine in numerous strains of Drosophila. Although tangential to our initial objective, we explored the influence of sex as a biological variable on locomotor response to dopaminergic modulation.ObjectiveTo describe sexually dimorphic behavioral responses to dopaminergic modulation in several strains of Drosophila.MethodsRecently eclosed, non‐entrained, male and female flies (n=16/group) were fed 5 mM methamphetamine in vehicle medium or vehicle medium (10% sucrose, 1% agarose gel) and monitored in the DAMS under constant light conditions for one week. Beam breaks recorded by the DAMS were summed into one‐hour bins and group means were calculated. Group means were then evaluated individually with repeat measures ANOVA, and included in a meta‐analysis using sex (male, female) as subgroups. A separate experiment used two wild‐type strains with established locomotor differences to evaluate the influence of sex and strain on locomotor response to 3 mM DL‐α‐Methyltyrosine (metyrosine), a tyrosine 3‐monooxygenase inhibitor. Metyrosine administration and DAMS monitoring was performed as described above, and group means were then evaluated using repeat measures ANOVA.ResultsMale and female flies displayed significantly increased locomotor activity than control flies when fed methamphetamine. Female flies of all strains displayed significantly higher baseline activity than male flies, but significantly less methamphetamine‐induced increases in locomotor activity than male flies. While male flies fed methamphetamine displayed persistent, steady increases in locomotor activity throughout the studies, female flies fed methamphetamine displayed progressively smaller locomotor differences Days 4–7, and no behavioral differences from control flies on Day 8.Male and female flies displayed significantly decreased decreased locomotor activity than control flies when fed metyrosine. Female flies of both strains displayed significantly higher baseline activity than male flies, but significantly more metyrosine‐induced decreases in locomotor activity than male flies. Metyrosine‐induced reductions in locomotor activity were persistent and steady for both male and female flies throughout the duration of the experiment.Support or Funding InformationThis work was supported in whole by the National Institute on Drug Abuse of the National Institutes of Health under award number R21DA039462. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of Kamikihito and Unkei-to on Sleep Behavior of Wild Type and Parkinson Model in Drosophila.

Parkinson’s disease (PD) is the second most common neurodegenerative disease, and it is associated with sleep behavior disorders. In Drosophila melanogaster disease model, human α-synuclein A30P overexpressing flies (A30P PD model) have been shown for levy body aggregation and movement disorders. We measured sleep rhythms in the A30P PD model flies using the Drosophila Activity Monitoring system and found that they develop sleep defects at 20 days after eclosion. Furthermore, the total amount of sleep is significantly reduced in middle-aged PD model flies and the reduction has been attributed to nighttime sleep. The number and length of sleep bouts also decreased in middle-aged A30P PD model flies. Feeding of the oriental traditional herbal medicines (Kampo), Kamikihito and Unkei-to significantly ameliorate the level of sleep defects in A30P PD model flies. The Kamikihito and Unkei-to recovered 60-min sleep bouts number in the A30P PD model flies to the level of young (5 days after eclosion) flies. Kamikihito recovered sleep both in wild-type and PD model flies. Unkei-to ameliorates not only sleep but also motor function in PD model flies. The data suggest that Kamikihito and Unkei-to might be useful for the sleep defects in human PD patients as well as healthy human.

0010 CHARACTERIZING THE INFLUENCE OF THE MOLECULAR CIRCADIAN CLOCK ON SLEEP ARCHITECTURE IN DROSOPHILA MELANOGASTER

The daily timing of sleep is controlled by a circadian clock, the disruption of which is physiologically and psychologically detrimental. While an identified network of circadian clock neurons controls the timing of sleep, a comprehensive understanding of how each of the components of the molecular clock affect sleep architecture is lacking. Though the loss of the circadian clock does not prevent sleep, it results in drastic changes in the quality of sleep. To better understand the ways in which the circadian clock governs sleep, we sought to systematically characterize the impact of loss of function mutations in Clock, cycle, period, and timeless on the sleep rhythm and sleep architecture in Drosophila under both entrained and free-running conditions and to investigate the role light plays in in the regulation of sleep in wild-type and mutant flies. Using the Drosophila activity monitoring system, we measured sleep in flies bearing loss of function mutations in the Clock (Clkjrk), cycle (cyc01), period (per01), and timeless (tim01) genes. Sleep was measured in under a 12:12h Light/Dark cycle, constant darkness, and constant light. To assess the impact of light on sleep, sleep was measured under various wavelengths and intensities. Our analysis of sleep in these lines reveals that all four mutations caused fragmented sleep. Loss of function mutations within the negative limb of the clock (i.e., per01 and tim01) resulted in altered daytime sleep architecture but no changes in total sleep time for over the diurnal or circadian cycle. Loss of function mutations in the positive limb of the circadian clock (i.e., Clkjrk and cyc01) result not only in significantly decreased sleep but also reveal a sleep promoting effect of light. We found that loss of function mutations in circadian clock genes resulted in significant effects on sleep quality with mutations in the negative and positive limb genes producing remarkably different phenotypes. none.

Melatonin attenuates hLRRK2-induced sleep disturbances and synaptic dysfunction in a Drosophila model of Parkinson's disease.

Sleep problems are the most common non-motor symptoms in Parkinson's disease (PD), and are more difficult to treat than the motor symptoms. In the current study, the role of human leucine-rich repeat kinase 2 (hLRRK2), the most common genetic cause of PD, was investigated with regards to sleep problems, and the therapeutic potential of melatonin in hLRRK2‑associated sleep problems was explored in Drosophila. hLRRK2 was selectively expressed in the mushroom bodies (MBs) in Drosophila and sleep patterns were measured using the Drosophila Activity Monitoring System. MB expression of hLRRK2 resulted in sleep problems, presynaptic dysfunction as evidenced by reduced miniature excitatory postsynaptic current (mEPSC) and excitatory postsynaptic potential (EPSP) frequency, and excessive synaptic plasticity such as increased axon bouton density. Treatment with melatonin at 4mM significantly attenuated the sleep problems and rescued the reduction in mEPSC and EPSP frequency in the hLRRK2 transgenic flies. The present study demonstrates that MB expression of hLRRK2 in flies recapitulates the clinical features of the sleep disturbances in PD, and that melatonin attenuates hLRRK2-induced sleep disorders and synaptic dysfunction, suggesting the therapeutic potential of melatonin in PD patients carrying LRRK2 mutations.

Regulation of Sleep by Insulin-like Peptide System in Drosophila melanogaster.

Most organisms have behavioral and physiological circadian rhythms, which are controlled by an endogenous clock. Although genetic analysis has revealed the intracellular mechanism of the circadian clock, the manner in which this clock communicates its temporal information to produce systemic regulation is still largely unknown. Sleep behavior was measured using the Drosophila Activity Monitoring System (DAMS) monitor under a 12 h light:12 h dark cycle and constant darkness (DD), and 5 min without recorded activity were defined as a bout of sleep. Here we show that Drosophila insulin-like peptides (DILPs) and their receptor (DInR) regulate sleep behavior. All mutants of the seven dilps and the mutant of their receptor exhibit decreases of total sleep except dilp4 mutants, whereas upregulation of DILP and DInR in the nervous system led to increased sleep. Histological analysis identified four previously unidentified neurons expressing DILP: D1, P1, L1, and L2, of which L1 and L2 belong to the LNd and LNv clock neurons that separately regulate different times of sleep. In addition, dilp2 levels significantly decrease when flies were fasted, which is consistent with a previous report that starvation inhibits sleep, further indicating that the dilp system is involved in sleep regulation. Taken together, the results indicate that the Drosophila insulin-like peptide system is a crucial regulator of sleep.

Hypnotic effects of a novel anti-insomnia formula on Drosophila insomnia model.

To assess the biological effects of the six-herb mixture Anti-Insomia Formula (AIF) extract using caffeine-induced insomnia Drosophila model and short-sleep mutants. Caffeineinduced insomnia wild-type Drosophila and short-sleep mutant flies minisleep (mns) and Hyperkinetic(Y) (Hk(Y)) were used to assess the hypnotic effects of the AIF in vivo. The night time activity, the amount of night time sleep and the number of sleep bouts were determined using Drosophila activity monitoring system. Sleep was defined as any period of uninterrupted behavioral immobility (0 count per minute) lasting > 5 min. Night time sleep was calculated by summing up the sleep time in the dark period. Number of sleep bouts was calculated by counting the number of sleep episodes in the dark period. AIF at the dosage of 50 mg/mL, effectively attenuated caffeine-induced wakefulness (P<0.01) in wild-type Canton-S flies as indicated by the reduction of the sleep bouts, night time activities and increase of the amount of night time sleep. AIF also significantly reduced sleeping time of short-sleep Hk(Y) mutant flies (P<0.01). However, AIF did not produce similar effect in mns mutants. AIF might be able to rescue the abnormal condition caused by mutated modulatory subunit of the tetrameric potassium channel, but not rescuing the abnormal nerve firing caused by Shaker gene mutation. This study provides the scientific evidence to support the use of AIF in Chinese medicine for promoting sleep quality in insomnia.

The effect of different illumination condition on drosophila circadian rhythm and 24 h sleep time

Objective To investigate the influence of illumination changes on the drosophila circadian rhythm and 24 h sleep time.Methods We collect the unmated fruit flies (a total of 128,single-sex) under CO2 anesthesia within 8 hours of eclosion.And put them into the group of normal light group,day and night reversed group,24 h light group and 24 h dark group with the simple random sampling method,male and female with 4 single-sex groups(n=32).Change the illumination conditions of the living environment of the fruit flies and use Drosophila Activity Monitoring System (DAMS) and Data Acquisition System (DAS),to observe and compare the changes of drosophila circadian rhythm and 24 h sleep time between the different illumination conditions.Results Compared with the normal light group,drosophila circadian rhythm of the day and night reversed group was significantly reversed,the number of fruit flies' activities of 24 h light group was increased,and circadian rhythm was decline,drosophila circadian rhythm of the 24 h dark group is still there,but frequent activity appears during the day,and the 19 : 00 activity peak disappears.Conclusion The drosophila circadian rhythm and 24 h sleep time changes with illumination conditions change. Key words: Drosophila; Circadian Rhythm; Biological Clock; LED

Go Signaling in Mushroom Bodies Regulates Sleep in Drosophila

Sleep is a fundamental physiological process and its biological mechanisms are poorly understood. In Drosophila melanogaster, heterotrimeric Go protein is abundantly expressed in the brain. However, its post-developmental function has not been extensively explored. Locomotor activity was measured using the Drosophila Activity Monitoring System under a 12:12 LD cycle. Sleep was defined as periods of 5 min with no recorded activity. Pan-neuronal elevation of Go signaling induced quiescence accompanied by an increased arousal threshold in flies. By screening region-specific GAL4 lines, we mapped the sleep-regulatory function of Go signaling to mushroom bodies (MBs), a central brain region which modulates memory, decision making, and sleep in Drosophila. Up-regulation of Go activity in these neurons consolidated sleep while inhibition of endogenous Go via expression of Go RNAi or pertussis toxin reduced and fragmented sleep, indicating that the Drosophila sleep requirement is affected by levels of Go activity in the MBs. Genetic interaction results showed that Go signaling serves as a neuronal transmission inhibitor in a cAMP-independent pathway. Go signaling is a novel signaling pathway in MBs that regulates sleep in Drosophila.

Processing Sleep Data Created with the Drosophila Activity Monitoring (DAM) System: Figure 1.

Adult behavioral assays have been used with great success in Drosophila melanogaster to identify circadian rhythm genes. In particular, the locomotor activity assay can identify altered behavior patterns over the course of several days in small populations, or even individual flies. Sleep is a highly conserved behavior that is required for optimal performance and, in many cases, life of an organism. Drosophila demonstrate a behavioral state that shows traits consistent with sleep: periods of relative behavioral immobility that coincide with an increased arousal threshold after ~5 min of inactivity, regulated by circadian and homeostatic mechanisms. However, because flies do not produce brain waves recordable by electroencephalography, sleep researchers use behavior-based paradigms to infer when a fly is asleep, as opposed to awake but immobile. Data on Drosophila activity can be collected using an automated monitoring system to provide insight into sleep duration, consolidation, and latency, as well as sleep deprivation and rebound. This protocol details the use of Counting Macro, an Excel-based program, to process data created with the Drosophila Activity Monitoring (DAM) System from TriKinetics for sleep analyses. Specifically, it details the steps necessary to convert the raw data created by the DAM System into sleep duration and consolidation data, broken down into the light (L), dark (D), light:dark cycling (LD), and constant darkness (DD) phases of a behavior experiment.

Sleep Deprivation Specifically Impairs Short-term Olfactory Memory in Drosophila

Sleep is crucial to memory consolidation in humans and other animals; however, the effect of insufficient sleep on subsequent learning and memory remains largely elusive. Learning and memory after 1-day sleep deprivation (slpD) was evaluated using Pavlovian olfactory conditioning in Drosophila, and locomotor activity was measured using the Drosophila Activity Monitoring System in a 12:12 light-dark cycle. We found that slpD specifically impaired 1-h memory in wild type Canton-S flies, and this effect could persist for at least 2 h. However, alternative stresses (heat stress, oxidative stress, starvation, and rotation stress) did not result in a similar effect and left the flies' memory intact. Mechanistic studies demonstrated that flies with either silenced transmission of the mushroom body (MB) during slpD or down-regulated cAMP levels in the MB demonstrated no slpD-induced 1-h memory impairment. We found that slpD specifically impaired 1-h memory in Drosophila, and either silencing of MB transmission during slpD or down-regulation of the cAMP level in the MB protected the flies from slpD-induced impairment.

A Video Method to Study Drosophila Sleep

To use video to determine the accuracy of the infrared beam-splitting method for measuring sleep in Drosophila and to determine the effect of time of day, sex, genotype, and age on sleep measurements. A digital image analysis method based on frame subtraction principle was developed to distinguish a quiescent from a moving fly. Data obtained using this method were compared with data obtained using the Drosophila Activity Monitoring System (DAMS). The location of the fly was identified based on its centroid location in the subtracted images. The error associated with the identification of total sleep using DAMS ranged from 7% to 95% and depended on genotype, sex, age, and time of day. The degree of the total sleep error was dependent on genotype during the daytime (P < 0.001) and was dependent on age during both the daytime and the nighttime (P < 0.001 for both). The DAMS method overestimated sleep bout duration during both the day and night, and the degree of these errors was genotype dependent (P < 0.001). Brief movements that occur during sleep bouts can be accurately identified using video. Both video and DAMS detected a homeostatic response to sleep deprivation. Video digital analysis is more accurate than DAMS in fly sleep measurements. In particular, conclusions drawn from DAMS measurements regarding daytime sleep and sleep architecture should be made with caution. Video analysis also permits the assessment of fly position and brief movements during sleep.

A Genetic Screen for Sleep and Circadian Mutants Reveals Mechanisms Underlying Regulation of Sleep in Drosophila

In order to characterize the genetic mechanisms underlying sleep, we have carried out a large-scale screen in Drosophila to identify short-sleeping mutants. The objectives of this study were as follows: (1) characterize the phenotypes of the shortest-sleeping mutants; (2) examine whether changes in arousal threshold or sleep homeostasis underlie short-sleeping phenotypes; (3) clone a gene affected in one of the shortest sleepers; and (4) investigate whether circadian mutants can be identified using light:dark (L:D) locomotor data obtained for studying sleep behavior. Locomotor activity was measured using the Drosophila Activity Monitoring System in a 12:12 L:D cycle. Drosophila research laboratory. Adult flies from the 2nd chromosome Zuker collection, which contain mutations in most of the nonessential genes on the Drosophila 2nd chromosome. Our analysis of sleep characteristics suggests that daily activity (but not waking activity) correlates with daily sleep time and that defects in sleep maintenance are more common than defects in sleep initiation. Our shortest sleepers have intact or increased sleep rebound following sleep deprivation but show reduced thresholds for arousal. Molecular analysis of one of the short-sleeping lines indicates that it is a novel allele of a dopamine transporter (DAT). Finally, we describe a novel approach for identifying circadian mutants using L:D data. Our data suggest that most short-sleeping mutant phenotypes in Drosophila are characterized by an inability to stay asleep, most likely because of a reduced arousal threshold.

Sleep homeostasis in Drosophila melanogaster.

The fruit fly Drosophila melanogaster is emerging as a promising model system for the genetic dissection of sleep. As in mammals, sleep in the fruit fly is a reversible state of reduced responsiveness to the external world and has been defined using an array of behavioral, pharmacologic, molecular, and electrophysiologic criteria. A central feature of mammalian sleep is its homeostatic regulation by the amount of previous wakefulness. Dissecting the mechanisms of homeostatic regulation is likely to provide key insights into the functions of sleep. Thus, it is important to establish to what extent sleep homeostasis is similar between mammals and flies. This study was designed to determine whether in flies, as in mammals, (1) sleep rebound is dependent on prior time awake; (2) sleep deprivation affects the intensity, in addition to the duration, of sleep rebound; (3) sleep loss impairs vigilance and performance; (4) the sleep homeostatic response is conserved among different wild-type lines, and between female and male flies of the same line. Motor activity of individual flies was recorded at 1-minute intervals using the infrared Drosophila Activity Monitoring System during 2 baseline days; during 6, 12, and 24 hours of sleep deprivation; and during 2 days of recovery. Sleep was defined as any period of uninterrupted behavioral immobility lasting > 5 minutes. Sleep continuity was measured by calculating the number of brief awakenings, the number and duration of sleep episodes, and a sleep continuity score. Vigilance before and after sleep deprivation was assessed by measuring the escape response triggered by 2 different aversive stimuli. Fly sleep research laboratory at UW-Madison. Adult flies of the Canton-S (CS) strain and 116 other wild-type lines (> or = 16 female and > or = 16 male flies per line). In wild-type CS flies, as in mammals, the amount of sleep recovered after sleep deprivation was dependent on prior time awake. Relative to baseline sleep, recovery sleep in CS flies was less fragmented, with longer sleep episodes, and was associated with a higher arousal threshold. Sleep deprivation in CS flies also reduced performance. Sleep duration and continuity increased after 24 hour of sleep deprivation in all the other wild-type lines tested. The sleep homeostatic response in fruit flies is a stable phenotype and shares most of, if not all, the major features of mammalian sleep homeostasis, thus supporting the use of Drosophila as a model system for the genetic dissection of sleep mechanisms and functions.

An automated assay of the behavioral effects of cocaine injections in adult Drosophila

Introducing Drosophila models in neuropharmacological research helps to discover new mechanisms of drug action. In fruit flies, the pharmacobehavioral approach has been used to evaluate the effects of drugs of abuse including cocaine. Standard procedures of cocaine administration to flies employ drug vaporization whereas behavior is evaluated either by trained observers or by videotaping followed by analysis via a computer-operated tracking system. Because in mammalian studies cocaine is typically administered by injection, a procedure that ensures precise and timely dose delivery, we developed a method for injecting cocaine into adult Drosophila. To objectively measure the behavioral response of flies to cocaine injections, we adapted the standard Drosophila Activity Monitoring System (Trikinetics). We found that in wild-type Canton S flies, cocaine injections produce a dose-dependent increase in the number of hyperactivity bursts and that repeated injections of cocaine produce behavioral sensitization. Acute responses to cocaine were observed also in period null ( per 0) mutant flies, but in these flies, repeated injections of cocaine did not produce sensitization. In conclusion, we developed a method for accurately measuring the behavioral effects of cocaine in adult fruit flies that can be applied to studies of the mechanisms of behavioral sensitization.