Animal Models of Anxiety and Depression

1
Animal Models of Anxiety and Depression

• György Lévay Ph.D.
• 04.25.2008

2
Central Nervous System Disorders

• Diseases of the autonomous nervous system
• Neuroendocrine disorders
• Movement disorders
• Anxiety disorders
• Depression
• Addiction, drug abuse
• Psychosis, schizophrenia
• Learning and memory disorders
• Dementias
• Neurodegenerative disorders (Alzheimers disease,
  Parkinson disease, prion diseases, etc)
• Sleep diturbances
• Attention deficit
• Pain
• Migraine
• Epilepsy
• Stroke, ischaemia, oedema
• Tumours

3
Drugs Acting on the Central Nervous System

• Hypnotics and sedatives)
• Anesthetics (general and local)
• Anxiolytics
• Antidepressants
• Antipsychotics
• Pain medications
• Antiepileptics
• Antimigrain agents
• Antiemetics
• Antiparkinsons
• Nootropics, cognitive enhancers
• Neuroprotectíve, antiischaemic agents
• Psychostimulants, drugs of abuse
• Drugs effective in the treatment of addiction

4
Major Neurotransmitters of the Central Nervous
System

• Glutamate (Glu)
• GABA
• Glycine (Gly)
• Dopamine (DA)
• Noradrenaline (norepinephrine) (NA, NE)
• Serotonin (5-HT)
• Histamine (H)
• Acetylcholine (Ach)
• Opiates (endorphines, encephalines, dynorphines)
• Cannabinoides
• Neuropeptides (CRF, NPY, CCK, ACTH, stb.)
• Purines
• Steroides and neurosteroides
• Neurotrophic factors (Neurotrophine, BDNF, GDNF,
  cytokines, stb)

5
Typical Connections in the CNS
6
Physiological and Pathological Anxiety
NORMAL PATHOLOGICAL
Jitter
Panic attacks
Obsessions, compulsions
Stage-fright
Flashbacks, nightmares
Nervousness
Pathological fear
Worrying
7
Anxiety Disorders (DSM-IV)

• Panic disorder (PD)
• Unexpected panic attacks associated with
  physiological symptoms of the autonomous nervous
  system
• Intensive fear
• Phobias
• Avoidance of places and situations where panic
  attacks occurred
• Often comorbide with depression and alcohol abuse
• 2 of the population, beginning in teens and
  early 20s
• Twice as common in women than men
• Current therapies
• Cognitive behavioral therapy
• Chronic antidepressant therapy( TCA, SSRI, MAOI)
• Occasionally (and acutely) alprazolam,
  clonazepam)

8
Reduction in Mean Number of Panic Attacks for
Patients (n78) with Panic Disorder Treated with
Paroxetine or Placebo


p lt0.019 vs. placebo. J Clin Psychiatry 199960
(suppl 18)
9
Reduction in Mean Hamilton Rating Scale for
Anxiety Score from Baseline for Patients with
Panic Disorder Treated with Paroxetine,
Clomipramine, or Placebo for 36 Weeks
J Clin Psychiatry 199960 (suppl 18)
10
Anxiety Disorders (DSM-IV)

• Obsessive-compulsive disorder (OCD)
• Obsessions (recurrent, intrusive and generally
  distressing thoughts, images or feelings
• Compulsions (repetitive, ritualistic behaviors
  aimed to alleviate obsessions)
• Obsessions and compulsions occupy at least 1 h
  daily causing significant distress and disability
• Often comorbid with depression
• 2 , early adolescence, or young adulthood
• Femalesmales
• Current therapy
• Cognitive behavioral therapy
• SSRI antidepressants

11
Anxiety Disorders (DSM-IV)

• Social phobia (SA or SP)
• Excessive fear of negative evaluations by others
• Extreme discomfort where patients feel people are
  watching or evaluating their performance
• Avoidance of such situations, occasional panic
  attacks
• Often comorbide with depression and alcohol abuse
• Late childhood, early adolescence
• Occurs more often in women although men are more
  likely to seek treatment
• Current therapy
• Behavioral therapy
• SSRI, MAOI
• Clonazepam, acutely

12
Pharmacotherapy for Social Anxiety Disorder
Percentage of responders to Paroxetine who
relapsed within 12 weeks after randomisation to
continued Paroxetine or placebo J Clin Psychiatry
199960 (suppl 9)
13
Mean Total Score on Liebowitz Social Anxiety
Scale (LSAS) for Paroxetine-treated and
Placebo-treated Patients






p 0.001 vs. placebo. J Clin Psychiatry 199960
(suppl 18)
14
Anxiety Disorders (DSM-IV)

• Post-traumatic stress disorder (PTSD)
• Develops subsequent to experiencing or witnessing
  a traumatic event
• Precipitating event life treatening assault
• Symptoms (lasting at least 4-6 weeks)
  reexperiencing the trauma, (flash-backs,
  memories, nightmares), avoidance of trauma
  associated sitiations numbing of emotions,
  arousal (not habituated)
• 7-8, twice as much women than men
• Current therapy
• Cognitive behavioral therapy
• Chronic antidepressant therapy( TCA, SSRI, MAOI)

15
Time Course of PTSD Symptom Improvement in
Responders to Paroxetine (N10)



_at_

_at_
_at_ _at_
_at_
_at_ _at_

Significant between 4-week intervals (plt 0.05).

_at_ Significant between weeks 0 and 8
(plt 0.001).
_at__at_ Significant
between weeks 4 and 12 (plt 0.001). J Clin
Psychiatry 199960 (suppl 18)
16
Anxiety Disorders (DSM-IV)

• Generalized anxiety syndrome (GAD)
• Excessive and uncontrollable worries about normal
  life events
• Symptoms of motor tension, autonomic reactivity
  or hypervigilance
• Minimum duration of 6 months
• Comorbide with depression and other mood
  disorders
• 3-4 , more women than men, any ages, familial
  association
• Current therapy
• Benzodiazepines
• Limited extent to antidepressants

17
Comparison of Diazepam, Imipramine and Trazodone
Efficacy in GAD










Adjusted postreatment means decreasing
(visitwise) sample size and 2-week end point
(n210) (in drug-placebo differences, asterisk
indicates plt0.05, double asterisks,
plt0.01) Rickels et al, 1993
18
Anxiety in Different Age-Groups

• Childhood
• Usually not hereditary (except special phobias)
• Often transient (family environment, early
  events)
• Behavioral inhibition (in unfamiliar situation
  or after meeting with unfamiliar person) born to
  be anxious (low arousal threshold in the amygdala
  and hypothalamus)
• PD is 2-3 times more frequent in adolescent girls
  than boys correlation with sexual maturation
• Separation Anxiety Disorder (SAD) occuring in
  childhood, only

19
Anxiety in Different Age-Groups (cont.)

• Youth, adult age
• 14.6 of the population is affected
• Tipicaly comorbid with depression (MD especially
  with PTSD) and drug abuse
• Dramatically decreased work performance (except
  simple phobias)
• Annual cost in the US only 50 billion USD
• Old age
• Prevalence is not decreasing significantly with
  age (approx. 10 )
• 48 of MD patient suffer from anxiety disorders
• Special anxiety of the old age developing after
  stroke, thyroid diseases, pulmonary diseases,
  dementias, etc.

20
Pharmacotherapy of Anxiety Disorders

• History
• Sedative drugs
• Ethanol
• Chloral hydrate
• Meprobamate
• Glutethimide
• Barbiturates

21
Pharmacotherapy of Anxiety Disorders (cont.)

• Current therapies
• Benzodiazepines

Lorazepam
Oxazepam
Diazepam
Chlordiazepoxide
Flumazenil
Tofizopam
Zolpidem
Alprazolam
Triazolam
22
Typical doses of benzodiazepines
23
Receptors for Benzodiazepines

• Binding site on the GABA-Cl--ion channel receptor
  commplex
• BZ1, (?1) high affinity to ?1 subunits and low
  affinity to ?5 subunits of GABAA receptors
• BZ2, (?2)

24
Genetic Dissection of Benzodiazepine-Induced
Behavior
25
Therapeutic indications of benzodiazepines

• Anxiety disorders (GAD, phobia, panic disorder-
  high potecy benzodiazepines)
• Anxiety accompanying other psychiatric or
  neurodegenerative disorders
• Alcohol and drug abuse
• Anxiety accompanying somatic disorders
• Insomnia
• Status epilepticus
• Anxiety generated by certain antipsychotic,
  antidepressant or antiemetic agents
• Muscular spazms
• Preoperative sedation

26
Side effects of benzodiazepines

• Limited clinical efficacy in certain diseases
• Sedation
• Muscle relaxant effect
• Anticonvulsant effect
• Tolerance
• Dependence
• Significant withdrawal reactions
• Deleterious impact on memory, particularly in the
  elderly
• Interaction with ethanol

27
Pharmacotherapy of Anxiety Disorders New
Mechanisms and Perspectives

• Glutamate receptor ligands
• mGluR2 agonists (LY-354740)
• AMPA allosteric modulators (negative and
  positive)
• NMDA antagonists
• CRF (corticotropin releasing factor) receptor
  antagonists
• Non-peptide CRF1 antagonists anxiolytic,
  antidepressant efficacy (CP-142635, CRA0165)
• CRF2 antagonists
• CCK (cholecistokinin) receptor antagonists
• CCKB antagonist CI-988 antipanic effect
• Other neuropeptides (NPY, Substance P, CART,
  Orexin, stb) receptor ligands
• Serotonergic compounds
• 5-HT2C antagonists
• 5-HT7 ligands

28
Pharmacotherapy of Anxiety Disorders (cont.)

• Current therapies
• Selective serotonin reuptake inhibitors (SSRI)

Fluoxetine
Citalopram
Sertraline
Paroxetine
Fluvoxamine
29
Usual doses of SSRI drugs
Overdosing and/or combination with MAOI
antidepressantsmight result in serotonin syndrome
(severe hyperthermia, muscle rigidity,
myoclonus, rapid changes in mental status and
vital signs)
30
Therapeutic indications of SSRI compounds

• Depression
• Bulimia (fluoxetine)
• Panic disorder
• Post-traumatic stress disorder
• Obsessive compulsive disorder
• Social anxiety disorder
• Alcohol and drug abuse
• Anxiety accompanying other psychiatric or
  neurodegenerative disorders

31
Side effects of SSRIs

• Slowly developing effect (minimum of 2 weeks)
• Acute anxiogenic effect
• Nausea, vomiting
• Diarrhoea
• Insomnia
• Decreased libido
• Sexual disfunction such as anorgasmia
• Agitation
• Aggressivity

32
Animal models of anxiety

• Methods based on unconditioned (spontaneous)
  response
• Exploratory activity
• elevated plus-maze
• light-dark (two compartment box)
• open field, closed field, etc.
• Social behavior
• social interaction
• maternal separation, ultrasonic distress calls
• Predator
• mouse defense test battery
• human threat (primates)
• predators call, odor associated avoidance
  response

33
Animal models of anxiety (cont.)

• Methods based on conditioned (learned) response
• Conflict models
• Vogel punished drinking
• Geller-Seifter conflict
• marmoset, pigeon conflict models
• Other
• four plate test
• active/passive avoidance learning
• conditioned ultrasonic vocalization (adult rats),
  etc.

34
Animal models of anxiety 1.

• Methods based on unconditioned (spontaneous)
  response
• Exploratory activity
• elevated plus-maze
• light-dark (two compartment box)
• open field, closed field, etc.
• Social behavior
• social interaction
• maternal separation, ultrasonic distress calls
• Predator
• mouse defense test battery
• human threat (primates)
• predators call, odor associated avoidance
  response
• Methods based on conditioned (learned) response
• Conflict models
• Vogel punished drinking
• Geller-Seifter conflict
• marmoset, pigeon conflict models
• Other
• four plate test

35
Animal models of anxiety 2.

• Normal (adaptive) anxiety
• Elevated plus-maze
• Ultrasonic distress calls
• Light-dark
• Marble burying
• Social interaction
• Stress-induced anxiety
• Stress-induced hyperthermia
• Vogel lick conflct
• Novelty-induced stressz
• Pathological anxiety
• Nneurochemically-induced anxiety
• mCPP, CCK4 or pentagastrine, CRF, etc.
• transgenicc models
• CRF overexpression
• 5-HT1A knock-out, etc.

36
Elevated plus-maze

• Source of anxiety open space, height, new
• environment
• Parameters measured time spent in the open arms
• entries into the open arms
• time spent in the closed arms
• entries into the closed arms
• total entries
• central time
• Anxiolytic effect statistically significant
  increase in open time or open
  entries
• Pelow, S, Chopin, P., File, S.E. and Briley, M.
  Validation of openclosed arm entries in an
  elevated plus-maze as a measure of anxiety in the
  rat. J. Neurosci. Methods, 1985, 14 149-167

37
Elevated plus-maze
38
Light-dark model

• Source of anxiety light, novelty,
• Parameters measuredtime spent in both area
• (horizontal, vertical activity)
• movement time in both area
• number of transitions
• Anxiolytic effect statistically significant
  increase in light (movement) time or
  number of transition
• Costall,B., Jones,B.J., Kelly,M.E., Naylor,R.J.
  and Tomkins,D.M. Exploration of mice in a black
  and white test box Validation as a model of
  anxiety. Pharm.Biochem.Behav., 1989, 32 777-785

39
Light-dark model
40
Ultrasonic distress calls

• Source of anxiety maternal separation
• Parameters measured time spent with ultrasonic
• vocalization
• total number of ultrasonic
• vocalization
• Anxiolytic effect statistically significant
  increase in either parameters
• measured
• WINSLOW J.T.and INSEL T.R. (1991) Serotonergic
  modulation of the rat pup ultrasonic isolation
  call studies with 5HT1 and 5HT2
  subtype-selective agonists and antagonists.
  Psychopharmacology 105513-520

41
Effect of EGIS-xxxxx on ultra- sonic distress
calls in rat pups
42
Social interaction

• Source of anxiety presence of an unfamiliar
• social partner
• Parameters measured exploration, ambulation,
• sniffing, rearing, grooming
• following, social contacts,
• allogrooming, sexual behavior,
• attack, fighting, biting
• defensive posture, immobility, etc
• Anxiolytic effect statistically significant
  increase in the number of
• social interactions,
• and decrease in aggression
• FILE,S.E. and HYDE,J.R.G.Can social interaction
  be used to measure anxiety?. Br.J.Pharmacol.
  1978, 62, 19-24

43
Effect of EGIS-xxxxx on social interactions under
stressful conditions
44
Marble burying

• Source of anxiety presence of an unfamiliar
• objects (potential source
• of danger)
• Parameters measured number of buried marbles
• Anxiolytic effect statistically significant
  decrease in the number of
• buried marbles
• BROEKKAMP, C.L.E., JOLY-GELOUIN, D., LLOYD, K.L.,
  and RIJK, H.W.Major tranquilizers can be
  distinguished from minor tranquilizers on the
  basis of effects on marble burying and
  swim-induced grooming in mice. Eur.J.Pharmacol.
  126223, 1986

45
Stress-induced hyperthermia(Handling order)

• Source of anxiety anticipatory anxiety,
• handling, new environment
• Parameters measured core temperature in the
• first three and last three
• animals in each group
• of 15 mice
• Anxiolytic effect body temperature of the last
• three animals are not significantly
• different from the first three
• BORSINI,F, LECCI,A, VOLTERRA,G and MELI,A, A
  model to measure anticipatory
• anxiety in mice? Psychopharmacology, 1989, 98
  207-211

46
Effect of EGIS-xxxx on stress- induced
hyperthermia
47
Vogel lick-conflict

• Source of anxiety stressful situation
• (48 h water depr.)
• conflict between thirst
• and punishment after drinking
• Parameters measured number of accepted
  punishment
• (electric shock)
• Anxiolytic effect statistically significant
  increase in the accepted shocks
• VOGEL, J.R., BEER, B. and CLODY, D.E. A simple
  and reliable conflict procedure for testing anti
  anxiety agents. Psychopharmacologia (Berl.),
  1971, 21 1-6

48
Vogel lick-conflict
49
mCPP-induced anxiety

• Source of anxiety chemically induced anxiety
• Parameters measured time spent in both side
• (horizontal, vertical activity)
• frequency of motion
• number of transition
• Anxiolytic effect statistically significant
  increase parameters
• measured in the lit compartment or
• in number of transition
• BILKEI-GORZO,A, GYERTYAN,I and LEVAY,G,
  mCPP-induced anxiety in the light-dark box in
  rats - a new method for screening anxiolytic
  activity, Psychopharmacol., 1998, 136 291-298

50
mCPP-induced anxiety
51
Mood disorders (DSM-IV)

• Major (unipolar) depression, episode
• Major (unipolar) depression, relapsing
• Dysthymia
• Other minor depression (recurrent short,
  ultradian)
• Hypomanic episode
• Manic episode
• Bipolar I. and II. disorder
• Psychotic depression or mania

52
Etiology of depression

• Genetic factors
• 8-18 times higher incidence among close relatives
• Relevant gens are not yet identified (various
  loci on chromosomes 4, 16, 18, 21 and X )
• Psychosocial factors
• Premorbid personality
• Life events
• Social support, social relations
• Age
• Childhood events
• Usually starts at young adulthood
• First episode in old age is very rare
• Prevalence women 18-34, men 10-19

53
Neurochemical-biochemical background of
depression

• Neurotransmitters and amino acids
• Norepinephrine
• Serotonin
• Dopamine
• GABA
• Glutamate
• Adetylcholine
• Neuropeptides
• Signal transduction, second messengers
• Presynaptic NaK-ATPase
• Postsynaptic second messengers
• Proteinkinases
• Transcription factors
• Neurotrophic factors
• Neuroendocrine alterations
• HPA-axis cortisol ?, CRF-induced ACTH-release ?,
  CRF ?
• HPT-axis TRH-induced TSH response is abnormal
  (30-40), liquor TRH ?

54
Neuroanatomical and functional alterations in
depression

• Decreased hippocampal volume, reduced dendritic
  arborisation
• The lymbic system and basal ganglia are both
  affected
• Reduced bloodflow in the frontal cortex and basal
  ganglia (PET)
• Membrane phospholipid metabolism is disturbed
  (fMRI)
• LTP ?

55
Symptoms of depression

• Depressed mood, intense dispair and lack of
  happiness
• Physical dispair, decreased energy, reduced
  activity
• Decreased attention and loss of concentration,
  memory impairments, mental slowing
• Reduced self-confidence, intensive feeling of
  guilt, self-deprecation
• Pessimistic worry, hopelessness
• Suicide, thoughts of self-destruction
• Psychomotor agitation or reduced motion
• Disruption of the normal circadian rhytm, sleep
  disturbances, loss of apetite, anorexia

56
Therapy of depression

• Depression
• Pharmacotherapy
• Tri- and tetracyclic antidepressants
• MAO-A inhibitors
• SSRI
• Mixed SSRI and SNRI
• Psychotherapy
• Supportive psychotherapy,
• Cognitive behavioral therapy
• Interpersonal therapy
• Family therapy
• Drama therapy
• Other
• Sleep deprivation, light therapy
• Electroconvulsive therapy
• Mania
• Pharmacotherapy
• Lithium, Carbamazepine, valproate
• Supplementary 1,4-benzodiazepines, antipsychotics

57
Requirement for animal models of depression
(McKinney and Bunney)

• It is reasonanly analogous to the human disorder
  inits manifestation or symptomatology
• There is a biological change that can be
  monitored
• The biological changes could be reversed by
  treatment effective in zhe human disease
• Widely reproducible

58
Animal models of depression

• Situation models
• Porsolt forced swimming
• Learned helplessness
• Tail suspension
• Inhibition of muricide activity
• Anatomical pathophisiological models
• Olfactory bulbectomy
• Chronic mild stress
• Biochemical (interaction) models
• Inhibition of tetrabenazine-induced ptosis
• Inhibition of apomorphine-induce hypothermia
• Inhibition of yohimbine-induced toxicity
• Widely reproducible

59
Porsolt forced swimming

• Symptoms of depression hopelessness,
• immobility,
• behavioral dispair
• abandoning
• of escape behavior,
• Parameters measured time spent with escape
• oriented movement,
• immobility
• (swimming, climbing)
• Antidepressant effect statistically significant
  decrease in immobility
• Weakness Effects of SSRI is not consequently
  detected
• PORSOLT,RD et al, (1977) Depression a new animal
  model sensitive to antidepressant treaments.
  Nature, 266730-732

60
Porsolt forced swimming
61
Porsolt forced swimming
62
Tail suspension

• Symptoms of depression hopelessness,
• immobility,
• behavioral dispair
• reduction in
• escape behavior,
• Parameters measured time spent with escape
• oriented movement,
• immobility
• (hangigg)
• Antidepressant effect statistically significant
  decrease in immobility
• Weakness Effects of SSRI is not consequently
  detected, better than Porsolt

63
(No Transcript)
64
(No Transcript)
65
Learned helplessness

• Symptoms of depression unavoidable shock,
• hopelessness,
• decreased reactivity
• Parameters measured escape failure
• Antidepressant effect statistically significant
  increase in number of escapes
• Weakness Symptoms are ceased 2-3 days after
• shocks
• WEISS, JM and KILTS, D (1998) Animal models of
  depression and schizophrenia. In Textbook of
  Psychopharmacology eds Nemeroff, CB and
  Schatzberg, H pp88-123

66
LEARNED HELPLESSNESS TEST IN THE RAT
plt0.05 plt0.001
67
Olfactory bulbectomy

• Symptoms of depression irritability,
  hyperactivity,
• decreased cognitive functions,
• aggressivity,
• neurochemical, neuroendocrine changes
• Parameters measured motor activity
• learning and memory parameters
• Antidepressant effect decreased hyperactivity
  increased cognitive functions
• increased habituation to new environment
• Weakness time consuming
• validity is questioned
• KELLY et al (1997) The olfactory bulbectomized
  rats as model of depression an update.
  Pharmacol.Ther. 74 299-316

68
Knock-out depression models
69
Models of learning and memory

• Classical conditioning
• Active avoidance tasks
• One way
• Two way
• Passive avoidance tasks
• Step through
• Step down
• Operant conditioning
• Skinner box
• Maze models
• Y-maze
• Morris water-maze
• T-maze
• Radial maze

70
Thank you for your attention....