20
Chronic treatment and loss of sensitivity to the In vivo effects of cannabinoids in mice: differences in mechanism of action Harinder Singh Spring Semester Rotation Under the supervision of Dr. Lance McMahon Dept of Pharmacology UTHSCSA

POST ROTATION TALK-UTHSCSA

Embed Size (px)

Citation preview

Page 1: POST ROTATION TALK-UTHSCSA

Chronic treatment and loss of sensitivity to

the In vivo effects of cannabinoids in mice:

differences in mechanism of action

Harinder Singh Spring Semester Rotation

Under the supervision of Dr. Lance McMahon Dept of Pharmacology

UTHSCSA

Page 2: POST ROTATION TALK-UTHSCSA

CANNABIS

Marijuana, Bhang, Ganja, etc

Page 3: POST ROTATION TALK-UTHSCSA

Abuse

Therapeutics

Why Study Cannabis ?

Page 4: POST ROTATION TALK-UTHSCSA

TYPES OF CANNABINOIDS

Δ9-Tetrahydrocannabinol (Δ9-THC), Plant Derived

Anandamide, Brain Derived

CP 55940, Synthetic

Page 5: POST ROTATION TALK-UTHSCSA

CANNABINOID RECEPTORSCB1 CB2

Brain

Lungs

Liver

Kidneys

T-cells

B-cells

Macrophages

Page 6: POST ROTATION TALK-UTHSCSA

Question

Do cannabinoids act through same receptor mechanism to

produce their behavioral effects

Experimental Objective

Chronic treatment with Δ9 THC and examine changes in

sensitivity to Δ9 THC other cannabinoids

Page 7: POST ROTATION TALK-UTHSCSA

Consequences of Chronic Δ9 THC Treatment

• Decrease in receptor density (Rodriguez de Fonesca et al., 1994, Fan et al., 1996)

• Decreased G Protein coupled receptor signaling (Dill and Howlett 1988)

• Reduced sensitivity to the effects of Δ9 THC Tolerance

Page 8: POST ROTATION TALK-UTHSCSA

SPECIFIC AIM

To examine changes in sensitivity to behavioral and physiological effects of Δ9 THC , CP 55940, Anandamide, and a non-cannabinoid (Midazolam) before and during chronic Δ9 THC treatment

Page 9: POST ROTATION TALK-UTHSCSA

Dose

D

urin

g Ch

roni

c TH

C

Befo

re

Anandamide

Effe

ct

Durin

g Ch

roni

c TH

C

Befo

re

Effe

ct

Δ9-THC

Dose

D

urin

g Ch

roni

c TH

C

Befo

re

CP 55940

Effe

ct

Dose

Same MechanismDifferent Mechanism

HYPOTHETICAL DATA

DoseEf

fect

Anandamide

Befo

re

Durin

g C

hron

ic T

HC

Dose

CP 55940

Befo

re

Durin

g C

hron

ic T

HC

Effe

ct

Page 10: POST ROTATION TALK-UTHSCSA

• C57BL/6J male mice (n=7)

• Rectal temperature probe

• Operant conditioning chamber

MATERIAL AND METHODS

Page 11: POST ROTATION TALK-UTHSCSA

Experimental Design

B A A

32 mg/kg Δ9-THC

Δ9-THC

CP 55940

Anandamide

Midazolam

Before Treatment

During Chronic Treatment

AfterTreatment

Page 12: POST ROTATION TALK-UTHSCSA

Doses (mg/kg)

RESULTSBefore Chronic Δ9THC Treatment

Δ9 THC CP 55940 Anandamide Midazolam

Veh 1 3.2 10 17.8 3228

30

32

34

36

38

Veh .032 .1 .32 1 3.228

30

32

34

36

38

Veh 3.2 10 32 56 10028

30

32

34

36

38

Veh 1 3.2 10 32 5628

30

32

34

36

38

Veh 1 3.2 10 17.8 320

25

5075

100125150

Veh .032 .1 .32 1 3.20

25

5075

100125150

Veh 3.2 10 32 56 1000

25

5075

100125150

Veh 1 3.2 10 32 560

25

5075

100125150

Δ: 4°C

Δ: 9°C

Δ: 7°CΔ: 5°C

Tem

pera

ture

(°C

)R

ate

(% c

ontr

ol)

Veh 1 3.2 10 17.8 3228

30

32

34

36

38

Veh .032 .1 .32 1 3.228

30

32

34

36

38

Veh 3.2 10 32 56 10028

30

32

34

36

38

Veh 1 3.2 10 32 5628

30

32

34

36

38

Veh 1 3.2 10 17.8 320

25

5075

100125150

Veh .032 .1 .32 1 3.20

25

5075

100125150

Veh 3.2 10 32 56 1000

25

5075

100125150

Veh 1 3.2 10 32 560

25

5075

100125150

Page 13: POST ROTATION TALK-UTHSCSA

Δ9-THC CP 55940

Doses (mg/kg)

During Chronic Δ9 THC TreatmentTe

mpe

ratu

re (°

C)

Rat

e (%

con

trol

)

Veh 1 3.2 10 17.8 32 5628

30

32

34

36

38

Veh .032 .1 .32 1 3.228

30

32

34

36

38

Veh 1 3.2 10 17.8 32 560

25

50

75

100

125

150

Veh .032 .1 .32 1 3.20

25

50

75

100

125

150

BeforeDuring Chronic Δ9THC

Page 14: POST ROTATION TALK-UTHSCSA

Veh 1 3.2 10 32 5628

30

32

34

36

38

Veh 1 3.2 10 32 56 10028

30

32

34

36

38

Veh 1 3.2 10 32 560

25

50

75

100

125

150

Veh 1 3.2 10 32 56 1000

25

50

75

100

125

150

Anandamide Midazolam

Doses (mg/kg)

Tem

pera

ture

(°C

)R

ate

(% c

ontr

ol)

During Chronic Δ9 THC Treatment

BeforeDuring Chronic Δ9THC

Page 15: POST ROTATION TALK-UTHSCSA

SUMMARY

Drugs Hypothermia Rate of Responding

Δ9 THC Yes Slight

CP 55940 Yes SlightAnandamide NO NO

Midazolam NO NO

Tolerance/Cross-tolerance

Page 16: POST ROTATION TALK-UTHSCSA

CONCLUSIONS

1. CP 55940 effects are mediated by receptor mechanism similar to Δ9 THC

2. a) Anandamide acts at different receptor ?

b) metabolized to non-cannabinoid receptor ligand ?

3. Different cannabinoid mechanisms for hypothermia and decreases in operant responding

Page 17: POST ROTATION TALK-UTHSCSA

FUTURE DIRECTIONS

1. To study specific receptor subtype involved – antagonism studies

2. CB1 and CB2 receptor Knockout mice studies

3. Studies using inhibitors of enzyme metabolizing anadamide

Page 18: POST ROTATION TALK-UTHSCSA

ACKNOWLEDGEMENT

Victoria Carlton

Jesse Usrey

Leah Hargrove

Veronica Sprayberry (Friendly neighbour)

Page 19: POST ROTATION TALK-UTHSCSA

QUESTIONS

Page 20: POST ROTATION TALK-UTHSCSA