screening of antianxiety drugs
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In vivo methodsMethods based on unconditioned (spontaneous) response:Exploratory activityElevated plus-mazeWater maze test Light-dark model (two compartment box)Staircase explorationSocial behaviourSocial interactionIsolation induced aggressionAnticipatory anxiety in mice *
Methods based on conditioned (learned) response:Conflict modelsVogel punished drinking/ Vogels lick conflict modelChemical induced methodmCPP induced anxiety in rats
2 open arms and 2 closed arms of 50 x 10 x 40cm dimensions
Open roof arrangement
Two open arms are opposite to each other.
Maze elevated at 50cm height above the ground.*
Experimental Design Group I : controlGroup II : standard Group III : test treated with dose x Group IV : test treated with dose 2x .
*Animals were allowed to explore in the maze for 5 min. Observations will done from adjacent room via remote TV camera.
Parameters Measured During Next 5 minutes:
time spent in the open arms
entries into the open arms
time spent in the closed arms
entries into the closed arms
total arm entries
Evaluation of results:Motor activity and open arm exploratory activity determined.Values of treated groups expressed as % of control values.Benzodiazepines and valproate decrease motor activity and increase exploratory time.
Anxiolytic effect indicated by:Increase in the proportion of time spent in open arms Increase in the proportion of entries into open arms
Circular tank of 100-150 cm diameter with 20-30 cm wall
A platform of 9-10 cm hidden 2-3 cm below water level
Add titanium dioxide susp. to make water opaque.
Temp : 23C.*
Rodents have exploratory activity
Animals placed in 2 chambered systems, where they can freely move between a brightly lit open field and a dark corner.
After treatment with anxiolytic - show more crossings between the two chambers and more locomotor activity.
Number of crossings between the light and dark sites is recorded.*
Methodology Apparatus - a dark and a light chamber divided by a photocell equipped zone.
Polypropylene animal cage (44 x 21 x 21 cm) is darkened with black spray over 1/3rd of its surface.
A partition containing 13cm(l) ,5 cm (h) opening is used for separating the dark one-third of the cage.
This case rests on an activity monitor which counts total locomotor activity.
An electronic system consisting of 4 sets of photocells across the partition. It automatically counts movements through the partition and records the time spent in the light and dark compartments.
Animals- treated 30 min before the test with drugs or vehicle given i.p. placed in the cage and observed for 10 min.
Groups of 6-8 animals used for each dose.
Observation No. Of crossings through the partition between the light and dark chambers compared with total activity counts during the 10 min.Loco motor activity also monitored.Evaluation:Anxiolytics like diazepam & buspirone increase locomotor activity and no. Of crossings.Non anxiolytics - not effective in this model.
Animal used: Male NMRI strain mice
Evaluation of results:
No. of animals with complete suppression of aggressiveness.
Reaction time noted.
Graduated scale of inhibition of aggressiveness is established.
Results of test group animals is compared with the control group results.*
Parameters measured : exploration, sniffing, rearing, social contacts, sexual behaviour, attack, fighting, biting ,defensive posture, immobility and climbing over the partner.
Evaluation :Values of treated partners compared with data from control animals ANOVA and t - test used.
mCPP - [ 1-(3-chlorphenyl) piperazine] a 5HT 1c agonist.
mCPP induces hypophagia and hypo-locomotion , inhibits social interaction, diminishes exploratory activity in light-dark box test, hyper therimia etc,.
Antagonism of these symptoms is used for screening of anxiolytic drugs.*
Anticipatory anxiety in miceWhen group housed mice are removed one by one from their former cage, the last mice always have a higher body temperature than the 1st one.The anticipatory increase in temperature was prevented by prior administration of diazepam & buspirone
*Test drug/solvent administered p.o to all the 18 animals. Record the basal temp by removing 1st 3 animals/group after 30 min Difference in the mean value of last three animals and basal value is calculated Vehicle treated group 1- 1.3C
*Male Sprague Dawley rats (200- 250g) are housed in groups of 6; exposed to 12 hour light/dark cycle with free access to food and water.
mCPP Induced Anxiety -Locomotion Study Test compound or vehicle are administered orally 1h or i.p 30 min before the locomotion test.
mCPP is injected i.p. in a dose of 7 mg/kg 20 min before the test.
The animals are placed individually in an automated locomotor activity cages and locomotion is recorded for 10 min.
Anxiolytic effect : disinhibition of locomotion.
Parameters measured : time spent in both sides (horizontal, vertical activity) frequency of motion number of transition
Anxiolytic effect : increase in parameters measured in the light/dark box or in number of transitions if test is active.*
Source of anxiety: thirsty, native rats are administered shocks while licking water.
Animals used: Sprague dawley rats.*
Apparatus*Clear Plexiglas box (38 x 38 cm) has a steel grid floor.A water bottle with metal drinking tube at 3 cm above the grid.A circuit is connected b/w the drinking tube and steel floor, so that the circuit completes if animal licks the tube.
Parameters measured:number of accepted punishments (electric shock)
Anxiolytic effect :statistically significant increase in the accepted shocks.*