The Effects of the Hallucinogen DOI on the Novel Object Recognition Task and Conditioned Place Preference Within the Rat Model Mitchell Morningstar Sponsor: George Rebec
The Effects of the Hallucinogen DOI on the Novel Object Recognition Task and Conditioned Place Preference Within the Rat Model
Mitchell MorningstarSponsor: George Rebec
Introduction: Motivation
Return of psychedelic assisted psychotherapies MDMA1
LSD2
Psilocybin3 Effects of psychedelics on
healthy individuals Good Friday study + subsequent
follow up4,5
Present work6
1. Mithoefer. 2011. J Psychopharmacol.2. Gasser. 2014.3. Johns Hopkins. Unpublished.4. Pahnke. 1963. Harvard PhD
Dissertation5. Doblin. 1991. J Transper Psycho.6. Griffiths et al. 2011. Psychopharm.
Introduction: Serotonin (5-HT)
Serotonin 2A (5-HT2A) agonism is thought to be the primary mediator of psychedelic activity1
▪ Expressed widely throughout the brain – highest within frontal cortex2
▪ Sensory cortices, basal ganglia, locus coeruleus, ventral tegmental area, and hippocampus also have some expression3
Other receptors talked about will be 5-HT2B, 5-HT2C
Frontal cortex
Basal Ganglia
Sensory cortices
HippocampusVentral Tegmental
Area
Locus Coeruleu
s
1. Vollenweider. 1998. Neuroreport.2. McKenna and Saavedra. 1987. Eur J Pharm. 3. Wong et al. 1987. Synapse.
Introduction: DOI
2,5-dimethoxy-4-iodoamphetamine (DOI) is a 5HT2A receptor agonist1
Similar to classical hallucinogens such as LSD, psilocybin (shrooms), and DMT
Active at 5-HT2A, 5-HT2B, 5-HT2C1
Hallucinogenic phenethylamine Produces head-twitch response2
Currently unregulated, not a popular recreational drug Long duration 1. Canal. 2012.
Drug Testing and Analysis
2. Keller. 1956. Science.
Introduction: Behavioral Effects
5HT2A activation… Alters time perception and perception of light1 Increases acquiring of associative learning, classical
conditioning responses2
Increases memory consolidation3
5HT2A blockade decreases rodent’s ability to retrieve complex memories4
1. Hanks. 2012. ACS Chem. Neuro.
2. Harvey. 1996. Behav. Brain Research.
3. Zhang et al. 2013. Front. Pharm.
4. Bekinschtein. 2013. J. Neuroscience
Introduction: Behavioral Tasks Novel Object Recognition (NOR) task tests rodent’s ability
to remember where and what Able to do so because of rodent’s innate preference for novel,
new objects in environment1 Entorhinal cortex and hippocampus are important areas for
storing, encoding and retrieving memories related to the NOR task2
Conditioned Place Preference (CPP) is often used to measure rewarding effects of drugs3
Associative learning – drug paired side becomes a conditioned stimulus able to cause rodent to preference it 3 1. Bevins. 2006. Nature Prot.
2. Cohen et al. 2015. Behav. Brain Research
3. Huston. 2013. Cell.
Hypothesis
Rats injected with DOI (0.2 mg/kg, i.p.) won’t be able to discriminate between the novel and familiar objects in the novel object recognition task.
Rats injected with DOI (0.2 mg/kg, i.p.) will spend less time in the drug-paired side of a conditioned place preference task.
Methods Novel Object Recognition (NOR) Three Phases
▪ Habituation▪ 10 Minutes of Free Roaming
▪ Familiarization▪ 10 Minutes with 2 Objects
▪ Trial▪ Delay of 1 hour▪ Injection (i.p.) 30 minutes into hour▪ One object is replaced with a new, novel
object▪ 5 Minute trial period
Time spent with each object was measured
Counterbalanced, data normalizedA B C
Figure adapted from Bevins 2006
A B CA
One placement (10 minutes)
One placement(5 minutes)
Methods
Conditioned Place Preference (CPP) 3 days of baseline data recorded to find
initial side preference Cocaine was paired on side least preferred Eight days of conditioning starting with
cocaine Tested 48 hours after last conditioning trial DOI or Saline injection given 30 minutes
prior to CPP test Time measured with digital stopwatches Biased
3 Days of Drug Naive
Baseline Data
Conditioning beginning with
cocaine (12.5 mg/kg), alternating to
saline
Saline or DOI (0.2 mg/kg)
pretreatment prior to assessing
CPP
Results: NOR
• Ratio of time spent with novel object
• Rats with DOI on-board during the testing phase
• Significantly worse at differentiating the novel object from the object they had been familiarized to 1 hour prior
n = 7 n = 7
Group TypeDOI Saline
Mea
n D
iscr
imin
atio
n R
atio
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
***
t(12) = -2.45, p < 0.05
Novel Object Recognition Results
n = 7 n = 7
Results: NOR
Group TypeDOI Saline
Tota
l Tim
e S
pent
With
Bot
h O
bjec
ts
0
5
10
15
20
25
30
35
40
45
50
t(12) = -2.00, p = 0.0914
Total Time
• Total time spent• No significant difference
between groups
n = 7 n = 7
Results: CPP
DOI Treated Group Saline Treated GroupPre
fere
nce
(sec
s) |
Dru
g P
aire
d S
ide
- Sal
ine
Pai
red
Sid
e
-100
-80
-60
-40
-20
0
20
40
60
80
100
***
• DOI decreases time spent on drug-paired side
• Animals treated with DOI did not have a preference for the drug-paired side
• Animals treated with Saline did have a preference for the drug-paired side
• A significant difference was found between the two groups
n = 4
n = 4
Results: CPP
DOI Treated Group Saline Treated Group
Per
cent
age
of B
asel
ine
0
20
40
60
80
100
120***
*
**
Percentage of Baseline Per Group
Saline PairedDrug Paired
• Figure describes the amount of time spent per side in each group as compared to baseline taken prior to cocaine conditioning
n = 4 n = 4
Results: Summary
Deficits in the NOR task were found suggesting that on-board DOI impairs object recognition memory No significant difference between the on-board DOI and
saline groups were found in overall time spent with both objects.
CPP was attenuated with DOI on-board suggesting that 5-HT2A agonism could be a target of attenuating the rewarding properties of drugs of abuse
Conclusion DOI decreased performance in the NOR task while
attenuating cocaine-induced CPP Recognition of the familiar object and recognition of the CS
were impaired, whether this is upstream perceptual deficit or downstream memory deficit can’t be determined
Future studies could employ region specific pharmacological manipulations while also utilizing electrophysiology in order to find changes in neuronal response
Future studies can further investigate the effects of 5-HT2A on memory, perception, and locomotion
Questions?