ASSESSMENT OF MOTOR ACTIVITY IN REGULATORY NEUROTOXICITY STUDIES: VALIDATION OF THE ETHOVISION VIDEO TRACKING SYSTEM IN RATS TREATED WITH AMPHETAMINE AND CHLORPROMAZINE

Sublethal Effects of Profenofos on Locomotor Behavior and Gill Architecture of the Mosquito Fish,Gambusia affinis

Subacute studies of profenofos on mosquito fish, Gambusia affinis, were carried out for 20 days to assess the locomotor behavior and structural integrity of gill in relation to bioaccumulation and targeted enzyme acetylcholinesterase (AChE; EC 3.1.1.7). The sublethal concentration of 0.13 mg/L (1/5 of LC50) altered locomotor behavior such as distance traveled and swimming speed in exposed fish. This could be due to inhibition in the activity of acetylcholinesterase and deformities in the primary and secondary lamella of gill. The bioaccumulation values indicated that the accumulation of profenofos was highest in viscera followed by head and body. The average bioconcentration factor values are 254.83, 6.18, and 2.52 microg/g for viscera, head, and body. The findings revealed that profenofos is highly toxic even at sublethal concentrations to the mosquito fish, Gambusia affinis.

Safety pharmacology assessment of central nervous system function in juvenile and adult rats: effects of pharmacological reference compounds

INTRODUCTION

Recent EU/US pediatric legislation and FDA/EMEA guidelines recognize the potential differences in safety profiles of drugs in adults versus young patients. Hence safety studies are recommended to investigate key functional domains of e.g. the developing CNS.

METHODS

Selected psychoactive stimulants (caffeine, d-amphetamine, scopolamine) and depressants (baclofen, diazepam, haloperidol, chlorpromazine, imipramine, morphine) were characterized upon single administration with regard to behavioural parameters, locomotor activity, body temperature, pro-/anti-convulsive activity (pentylenetetrazole, PTZ), and nocifensive responses (hotplate) in neonatal (2 weeks), juvenile (4 weeks) and adult rats (8-9 weeks).

RESULTS

In vehicle-treated rats, behavioural patterns matured with age, locomotor activity and handling-induced rise in body temperature were enhanced, whereas PTZ convulsion threshold dose and nocifensive response latency decreased. Single test compound treatment elicited behavioural effects characteristic for psychoactive drugs with stimulating and depressing properties regardless of age. However, incidence of certain behaviours, and magnitude of effects on locomotor activity and body temperature varied with age and became generally more pronounced in adult rats. Pro-/anti-convulsive effects and delayed nocifensive responses did not differ between juvenile and adult rats.

CONCLUSION

CNS effects of selected psychoactive reference compounds were qualitatively similar, but quantitatively different in neonatal, juvenile and adult rats.

Changes in Behavior and Brain Acetylcholinesterase Activity in Mosquito Fish, Gambusia affinis in Response to the Sub-Lethal Exposure to Chlorpyrifos

Sub-lethal studies of chlorpyrifos, O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate on mosquito fish, Gambusia affinis were carried out in vivo, for 20 days to assess the locomotor behavior in relation to bioaccumulation and interaction with a targeted enzyme, acetylcholinesterase (AChE, EC: 3.1.1.7). Fish exposed to sub-lethal concentration of 60 microg/L (1/5 of LC 50) were under stress, and reduced their locomotor behavior like distance travelled per unit time (m/min) and swimming speed (cm/sec) with respect to the length of exposure. The alteration in locomotor behavior of fish may be due to an accumulation of acetylcholine (ACh), a neurotransmitter at synaptic junctions, due to the inhibition of AChE enzyme activity (40 to 55%) in brain and also bioaccumulation of the toxicant in different parts of fish. The bioaccumulation values indicated that the accumulation of chlorpyrifos was maximum in viscera followed by head and body. The average bio-concentration values are 0.109, 0.009 and 0.004 microg/g for viscera, head and body with depuration rates of 2.24, 1.69 and 0.39 ng/h respectively. It is evident from the results that the sub-lethal concentration [1/5 of LC 50; equivalent to Lowest Observed Effect Concentration (LOEC)] of chlorpyrifos can able to alter the locomotor behavior of G. affinis in relation to the length of exposure. The findings revealed that the locomotor activity of test organism could be considered as a suitable marker to evaluate the affect of toxicant even at LOEC levels.

Sublethal effects of monocrotophos on locomotor behavior and gill architecture of the mosquito fish, Gambusia affinis

Subacute studies of monocrotophos [Dimethyl (E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] on mosquito fish, Gambusia affinis, were carried out in vivo for 24 days to assess the locomotor behavior, structural integrity of gill, and targeted enzyme acetylcholinesterase (AChE, EC: 3.1.1.7) interactions. Monocrotophos (MCP) can be rated as moderately toxic to G. affinis, with a median lethal concentration (LC(50)) of 20.49 +/- 2.45 mgL(-1). The fish exposed to sublethal concentration of LC(10) (7.74 mgL(-1)) were under stress and altered their locomotor behavior, such as distance traveled per unit time (m min(-1)) and swimming speed (cm sec(-1)) with respect to the length of exposure. Inhibition in the activity of brain AChE and deformities in the primary and secondary lamellae of gill may have resulted in failure of exchange of gases. The maximum inhibition of 95% of AChE activity was observed on days 20 and 24. Morphological aberrations in the gills were also studied during exposure to the sublethal concentration of monocrotophos for a period ranging from 8 to 24 days. The extent of damage in gill was dependent on the duration of exposure. The findings revealed that inhibition in brain AChE activity and structural alteration in gill were responsible for altering the locomotor behavior of exposed fish.

EthoVision: a versatile video tracking system for automation of behavioral experiments

The need for automating behavioral observations and the evolution of systems developed for that purpose is outlined. Video tracking systems enable researchers to study behavior in a reliable and consistent way and over longer time periods than if they were using manual recording. To overcome limitations of currently available systems, we have designed EthoVision, an integrated system for automatic recording of activity, movement, and interactions of animals. The EthoVision software is presented, highlighting some key features that separate EthoVision from other systems: easy file management, independent variable definition, flexible arena and zone design, several methods of data acquisition allowing identification and tracking of multiple animals in multiple arenas, and tools for visualization of the tracks and calculation of a range of analysis parameters. A review of studies using EthoVision is presented, demonstrating the system's use in a wide variety of applications. Possible future directions for development are discussed.