Nicotine prevents striatal dopamine loss produced by 6hydroxydopamine lesion in the substantia nigra

1
Nicotine prevents striatal dopamine loss produced
by 6-hydroxydopamine lesion in the substantia
nigraGustavo Costa, J.A. Abin-Carriquiry,
Federico Dajas (2001). Brain Research
Interactive. 888 336-342

• Presented by Natasha Frett

2
Objective

• To evaluate the therapeutic action of nicotine in
  preventing striatal dopamine loss in lesions of
  the substania nigra in Parkinsons disease.

3
The Brain Basal Ganglia

• Found in the deep white matter of the cerebral
  cortex
• 4 primary nuclei
• The striatum (caudate nucleus, putamen, ventral
  straitum)
• Globus pallidus ( or pallidum)
• Substantia nigra (pars reticulata and pars
  compacta)
• The subthalamic nucleus

4
The Brain Basal Ganglia
5
The Brain Basal Ganglia
6
Parkinsons disease

• Neurological disease 1st described in 1817 by Dr.
  James Parkinson in his Essay on the Shaking
  Palsy.
• Deterioration of neurons in the substantia nigra
  (pars compacta).
• - Deterioration due to defects in cellular
  mechanisms involving the breakdown of protein.
• - Causes the accumulation of debris that clogs
  and kills brain cells.

7

• - Reduces the amount of dopamine
• - Dopamine inhibits the secretion of
  Acetylcholine, the primary neurotransmitter to
  muscles.
• - Dopamine acts on the Nicotinic- acetylcholine
  receptors (nAChR) in the post-synapse
• - Also reduces the number of receptors

8
Probable Causes

• National Human Genome Research Institute (NHGRI)
  and the National Institute of Neurological
  Disorders and Stroke (NINDS) at the National
  Institutes of Health identified an abnormal gene
  on chromosome 4, that maybe responsible for a
  small fraction of Parkinsons disease cases.

9
Probable Causes

• Inherited susceptibility.
• Elements in the environment such as chemicals
  (insecticides and herbicides) induces the onset
  of the disease.

• Viral infection
• Toxic insult

10
Symptoms
Some of the symptoms of Parkinsons disease

• Tremor in resting muscles
• Muscular rigidity of the arms, legs and neck
• Bradykinesia (difficulty initiating movement)

• Loss of balance
• Depression
• Memory problems and dementia
• Speech problems
• Difficulty swallowing
• Sleep disorders

11
Diagnosis and Treatment

• Diagnosis
• Familial history of Parkinsons disease
• Physical examination
• Treatment
• Drug therapy. (Eg. L-dopa)
• Surgery

12
Nicotine prevents striatal dopamine loss.

• Objective
• Subjects

• To observe the neuroprotective effects of
  nicotine on induced substania nigra lesions in
  rats.
• Sprague Dawley rats (230-260 g).
• Housed in groups of 6 and given access to food
  and water.
• 12hr light/dark cycles

13
Nicotine prevents striatal dopamine loss.

• Solutions
• 6-OHDA
• Nicotine
• Chlorisondamine

• 6-OHDA, aCSF, 0.2 ascorbic acid.
• (-) nicotine saline
• Chlorisondamine (CHL) saline

14
Nicotine prevents striatal dopamine loss.

• Methods

• 6 rats were injected with similar volumes of aCSF
  and 0.2 ascorbic acid, for 6-OHDA control.
• Partial lesioning (6 ?g dose )
• 5 groups of 8 rats were obtained and were given
  different nicotine at different times.
• Each experimental group had a control using
  6-OHDA saline

15
Nicotine prevents striatal dopamine loss.

• Methods

• A small hole was made in the skull and a needle
  attached to a syringe was lowered into substantia
  nigra.
• At 37C, 2 ?l of 6-OHDA solution was injected for
  4 mins in the right substantia nigra.
• 2 doses 3 ?g/ ?l (6 ?g)
  5 ?g/ ?l (10 ?g).
• Received 1mg/kg of nicotine treatments
  subcutaneously in differing time periods.

16
Protocols
17

• 10 ?g dose received nicotine 4hrs before
  injection of 6-OHDA and 20, 44, 68 hrs after.
  (protocol 3)

18
Neuro-chemical analysis

• Brains were removed, sonicated in .1M perchloric
  acid and centrifuged at 15000g for 15mins at 4C
• Injected into a HPLC system.

19
Results

• Rationale
• Intranigral injections of both doses of
• 6-OHDA showed a decrease in dopamine levels in
  tissues.

20
Results Intranigral injections
Dopamine levels as ng/g of wet weight S.D
21
Results

• Nicotine had neuro-protective effects which
  enabled the neurons to produce more dopamine.

22
6?g of 6-OHDA and Nicotine
Dopamine in nicotine and CHL treatments
23
10?g of 6-OHDA and Nicotine
Dopamine in nicotine treatment
24
6?g and 10?g doses of 6-OHDA
25
Protocols
26
Activity of Nicotine in Protocols
27

• Dopaminergic neurons synthesize neurons.
• DOPAC is a metabolite of dopamine.
• Increased ratios indicate an increase in dopamine
  turnover. This indicates increased activity in
  dopaminergic neurons.
• Note damage is caused to nicotinic receptors.

28
DOPAC/DA ratios
29
DOPAC/DA ratios
30
Neuroprotective effects of Nicotine

• Increased ratios of DOPAC/DA indicates that the
  protective effects is linked to the nicotinic-
  acetylcholine receptors (nAChR).
• Nicotine causes an increase in the (nAChR)
  However, the neuroprotective effect is due to the
  activation of and function of these receptors.

31
Neuroprotective effects of Nicotine contd

• Nicotine increases basic fibroblast growth
  factors which protects against neurotoxicity.
• Fibroblast factor peaks 4 hrs after injection and
  returns to normal levels 24 or 48 hrs after
  injection.

32
Conclusion

• Parkinsons disease is a neurological
  degenerative disease that affects transmittance
  of dopamine
• Dopamine regulates the secretion of
  acetylcholine- muscle receptor
• Dopamine transmittance occurs in the basal
  ganglia, which sends inhibitory stimuli to
  cerebral cortex

33

• Defects in cellular mechanisms cause the
  formation forms debris that clog and kill cells.
• Dopaminergic neurons and Nicotinic-acetylcholine
  receptors are destroyed at dopaminergic
  terminals, reducing binding at the postsynapse.
• This increases the presence of Acetylcholine and
  uncontrolled stimuli to muscle.

34

• Nicotine increases the amount of
  Nicotinic-acetylcholine receptors and increases
  the level of trophic factors.

35
References

• Gustavo, C., Abin-Carriquiry, J.A., Dajas,
  F.(2001) Nicotine prevents striatal dopamine loss
  produced by 6-hydroxydopamine lesion in the
  substantia nigra. Brain Research Interactive Vol
  888336-342
• Court, J.A., Martin-Ruiz, C., Graham A., Perry,
  E. (2000) Nicotinic receptors in human brain
  topography and pathology. Journal of Chemical
  Neuroanatomy Vol. 20 281-298
• Quik, M., Jeyarasasingam, G.(2000) Nicotinic
  receptors and Parkinsons disease. European
  Journal of Pharmacology Vol. 393 223-230
• Kandel, E.R., Schwartz, J.H. and T. Jessell
  (2000) Principles of neural science 4th ed.
  McGraw-Hill. New York

36

• Division of intramural research
  http//www.nhgri.nih.gov/DIR/LGDR/PARK/about_parks
  .html
• Washington University School of Medicine
  http//thalamus.wustl.edu/course/cerebell.html