Translating from Animal Models to Human Schizophrenia - Insights into Pathophysiology, Treatment and...
Transcript of Translating from Animal Models to Human Schizophrenia - Insights into Pathophysiology, Treatment and...
Translating from Animal Models to
Human Schizophrenia: Insights into Pathophysiology, Treatment
and Prevention
Anthony A. Grace, Ph.D.Departments of Neuroscience,
Psychiatry and Psychology
University of Pittsburgh
Disclosures: Johnson & Johnson, Lundbeck, Pfizer, GSK, Merck, Takeda,
Dainippon Sumitomo, Otsuka, Lilly, Roche, Asubio, Akerrmes, Abbott
We have used an animal model based on a disruption of
neuronal development with MAM (methyl azoxymethanol
acetate) that has provided new insights into the complex
circuitry thought to link dopamine system responsivity and
schizophrenia
MAM is a DNA alkylating agent that is given at
gestational day 17, which is a sensitive period
corresponding to the second trimester in humans
MAM developmental model of schizophrenia
1. Anatomical Evidence:- thinning of limbic cortical structures
- increased cell packing density
3. Pharmacological Evidence:- increased response to PCP
- increased locomotion to amphetamine in adult
- no difference in response to amphetamine in prepubertal stage
2. Behavioral Evidence:- impairment in prepulse inhibition of startle
- impairment in reversal learning
-impairments in extradimensional shift
-impairment in latent inhibition
-impairment in social interaction
The increased amphetamine response is consistent with a
role for dopamine in schizophrenia
Moore, Ghajarnia, Jentsch, Geyer, and Grace (2006). Biological Psychiatry 60: 253-264.
Interpretation:
In the MAM model of schizophrenia, there is a hyper-
responsivity of the dopamine system analogous to that
observed in schizophrenia patients.
Current clinical data shows that hyperactivity in the
hippocampus is correlated with the psychotic state of
schizophrenia.
Is the hippocampus hyperactive in the MAM animal as
it is in the schizophrenia patient?
Hippocampal Activity in MAM-treated Rats
Ctrl MAM0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
Avg
FR
(H
z)
Does this also affect DA neuron activity?
Lodge and Grace (2007) Journal of Neuroscience 27: 11424-11430.
Spontaneously active DA neuron
“silent” DA neuron
“Population Activity”
Population
Activity
Firing Rate
Firing Pattern
DA Neuron Activity in MAM-treated Rats
SAL MAM0.0
0.5
1.0
1.5
2.0
2.5 *
Cell
s/T
rack
SAL MAM0.0
2.5
5.0
7.5
10.0
Avg
FR
SAL MAM0
10
20
30
40
50
Avg
% B
urs
t F
irin
gThe increase in the number of DA neurons firing is a likely correlate of
increased F-DOPA uptake in UHR and schizophrenia (Howes, McGuire)
Lodge and Grace (2007) Journal of Neuroscience 27: 11424-11430.
Effects of Hippocampus Inactivation on
DA Neuron Activity
SAL MAM0.0
0.5
1.0
1.5
2.0
2.5 *
Cell
s/T
rack
SAL MAM0.0
2.5
5.0
7.5
10.0
Avg
FR
SAL MAM0
10
20
30
40
50
Avg
% B
urs
t F
irin
gWhy is the hippocampus hyperactive?
Lodge and Grace (2007) Journal of Neuroscience 27: 11424-11430.
Zhang et al, Schiz. Res., 2002
Reduction in density of PV+ GABAergic inhibitory neurons
in schizophrenia
No significant differences in dorsal hippocampus
MAM rats display a regionally selective reduction in PV
interneuron number
PV - Interneuron Cell Counts
MAM
**
mPFC vHipp0
1000
2000
3000
4000Control
cells
/mm
2
Lodge, Behrens & Grace (2009) J. Neuroscience 29:2344-2354
What causes PV interneuron loss in the
Vhipp?
Stress and Psychiatric Disorders:
-Stressful stimuli in schizophrenic patients will exacerbate
the positive psychotic symptoms of this disorder
-Stress may also play a role in the etiology of schizophrenia
(Johnstone, Murray)
-Stress is known to cause a loss of parvalbumin interneurons
in the hippocampus, which are the same neurons lost in
schizophrenia patients and MAM rats
Are MAM rats more stressed prepubertally than controls?
MAM-treated rats show increased anxiety, amygdala
activity, and response to stress prepubertally
Zimmerman, Bellaire, Ewing, and Grace (2013) Neuropsychopharmacology 38: 2131-2139.
Sal MAM
Firin
g R
ate
(H
z)
0.0
0.1
0.2
0.3
0.4
0.5
0.6 ***
If stress plays a role in the
developmental etiology of
schizophrenia, this would suggest
that an early intervention in
susceptible individuals may help to
prevent the transition to psychosis
This was tested in the MAM model by
administering the anti-anxiety agent
diazepam peripubertally and testing the
animals as adults
A Dose of Diazepam was used that Normalizes Anxiety in
Peripubertal MAM Rats
BLA spontaneous firing with acute
diazepam administration (PD35-42)
• Elevated plus maze with acute diazepam administration (PD38-42)
MAM:Veh MAM:DZ
Tim
e S
pe
nt
in
Op
en
:Op
en
+C
lose
d A
rms
0.0
0.1
0.2
0.3
0.4
0.5
0.6
MAM:Veh MAM:DZ
En
trie
s in
to
Op
en
:Op
en
+C
lose
d A
rms
0.0
0.1
0.2
0.3
0.4
0.5
0.6
**
**
Sal MAM MAM:DZ
Firin
g R
ate
(H
z)
0.0
0.1
0.2
0.3
0.4
0.5
0.6 *** ***
Du and Grace (2013) Neuropsychopharmacology 38:1881-1888.
Du and Grace (2016) Neuropsychopharmacology doi: 10.1038/npp.2016.42. [Epub ahead of print]
Sal MAM MAM:DZ
PV
In
tern
eu
ron
Pop
ula
tio
n E
stim
ate
0
1000
2000
3000
4000
5000
6000
Sal MAM MAM:DZ
PV
In
tern
eu
ron
s /
mm
3
0
1000
2000
3000
4000
5000 *
***
**
*
***
***Peripubertal Administration of Diazepam Partially Prevents
PV Neuron Loss and DA neuron activation in the Adult
Du and Grace (2016) Neuropsychopharmacology doi: 10.1038/npp.2016.42. [Epub ahead of print]
Puberty: 35-36 DO
Inject dams: E17
MAM or Saline
x
Inject males: 31-40 DO
Diazepam (5mg/kg) or Saline
Record population activity in VTA
2+ months old
x
Design:
0
0.5
1
1.5
2
2.5
Sal:Veh Sal:DZ MAM:Veh MAM:DZ
Cell
s/ T
rack
Converging evidence from clinical and basic science
studies suggest that the inability to regulate stress early in
life can lead to pathological changes in the hippocampus
that may underlie the emergence of schizophrenia in the
adult.
This suggests that major stress by itself during this critical
peripubertal period could lead to parvalbumin loss and
induce a psychosis-like state
The fact that MAM can be circumvented suggests that
genetic predisposition likely doesn’t CAUSE schizophrenia,
but instead facilitates the impact of environmental factors on
disease susceptibility.
PD31 PD40 PD65
Behavioral
tests
Stress
exposure
Behavioral tests:
- EPM (PD65)
- NOR (PD66: habituation;PD67: acquisition
and retention trials)
- Locomotor response to Amph (PD68-PD69)
VTA recordings
PD69 PD77
Stress exposure (groups):
- Naïve
- Restraint stress (PD31, PD32, and PD40 – 1h)
- Footshock (PD31-40 – 25 shocks, 1.0mA/2s)
- Footshock + Restraint stress
Stress exposure during adolescence
Only FS+RS induced higher amphetamine-induced locomotion
Naiv
eR
SFS
RS+FS
0
2 0 0 0
4 0 0 0
6 0 0 0
8 0 0 0
1 0 0 0 0
B a s e lin e
Lo
co
mo
to
r a
ctiv
ity
(c
m)
Naiv
eR
SFS
RS+FS
A fte r a m p h
*
510
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
0
3 0 0
6 0 0
9 0 0
1 2 0 0
1 5 0 0
1 8 0 0
Lo
co
mo
to
r a
ctiv
ity
(c
m)
T im e (m in )
R S
N aive
510
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
0
3 0 0
6 0 0
9 0 0
1 2 0 0
1 5 0 0
1 8 0 0
Lo
co
mo
to
r a
ctiv
ity
(c
m)
T im e (m in )
N aive
F S
510
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
0
3 0 0
6 0 0
9 0 0
1 2 0 0
1 5 0 0
1 8 0 0
Lo
co
mo
to
r a
ctiv
ity
(c
m)
T im e (m in )
R S + F S
N aive
Gomes and Grace (2016) doi 10.1093/schbul/sbw156.
*
Naive RS FS FS+RS
FS+RS also increased the number of spontaneously active DA cells in the VTA, but did not change the firing rate and burst activity
Medial Central Lateral
VTA subregions
….with greatest effect in the lateral VTA
*
Gomes and Grace (2016) doi 10.1093/schbul/sbw156.
PD65 PD75 PD81
FS+RS
PD88
Stress exposure during adulthood
VTA recordings(1-2 weeks after stress)
Gomes and Grace (2016) doi 10.1093/schbul/sbw156.
This decrease in VTA activity
in the medial VTA is consistent
with models of depression
STRESS(vulnerable periods)
↑ Oxidative stress PV loss in the vHIP
↑ vHIP activity
Psychosis
↑ BLA activity
↑ VTA activity
Stress leads to PV neuron loss in the hippocampus
mPFC
Our previous work shows that the mPFC can potently inhibit stress responses in the BLA
We tested whether inactivation of the plPFC would exacerbate the deleterious effects of stress
mPFC dysfunction would increase
vulnerability to stress
PD31 PD40 PD65
Behavioral tests
Stress exposure
Behavioral tests:- EPM (PD65)- NOR (PD66: habituation; PD67: acquisition and retention trials)- Locomotor response to AMPH (PD68-PD69)
VTA recordings
PD69 PD77
Stress exposure:- Naïve- Footshock (PD31-40 – 25 shocks, 1.0mA/2s)
PD25
Lesion of the mPFC
Experiment 3: mPFC lesion increases vulnerability to stress?
mPFC dysfunction increases vulnerability to stressmPFC lesions alone increase anxiety
in EP
With mPFC lesion, FS alone increased amphetamine locomotion
Gomes and Grace (2016) doi 10.1093/schbul/sbw156.
If we can identify susceptible individuals and intervene early
enough, we may be able to prevent the deleterious effects
of stress and the transition to schizophrenia.
Therefore the deleterious impact of stress, combined with
factors predisposing an individual to the impact of stress,
may underlie susceptibility to schizophrenia
The increased response to stress may be mediated by a
failure of the mPFC to limit the impact of stress exposure
This is critically dependent on the timing of the stress:
-exposure during adolescence → PV loss and
schizophrenia
-exposure during adulthood → PV protected and
depression
Ali Charara Dan Lodge Collaborators:
Mark Bellaire Witek Lipski Benjamin S. Bunney, Yale
Pauline Belujon Michael Mana Margarita Behrens, UCSD
Brandon Bizup Jared Moreines James Cook, UWM
David Bortz Holly Moore Lorenz Deserno, Charite Univ.
Deanne Buffalari Eric Nisenbaum Andreas Heinz, Charite Univ.
Chun-hui Chang Patricio O’Donnell Philip McGuire, Kings Coll.
Pierangelo Cifelli Shao-Pii Onn Urs Meyer, ETH Zurich
Cynthia Correll Mary Patton Gemma Modinos, Kings Coll.
Yijuan Du Vince McGinty Celeste Napier, Rush
Samuel Ewing Michele Pucak Michael Pogue-Geile, Univ. Pitt
Stan Floresco Meera Ramsooksing Susan Sesack, Univ. Pitt
Krysta Fox Millie Rincon-Cortes Linda Rinaman, Univ. Pitt
Mehdi Ghajarnia Heather Rose Mark Ungless, Imperial Coll.
Kathryn Gill J. Amiel Rosenkranz Dean Wong, Hopkins
Felipe Gomes Thibault Sesia
Yukiori Goto Ian Smith
David Harden Susie Sonnenschein
Jeffrey Hollerman Judy Thompson
Hank Jedema Chris Todd
David Jentsch Ornella Valenti
Antonieta Lavin Anthony West
Steve Laviolette Eric Zimmerman
Xiyu Zhu
Acknowledgements
Funding: NIMH