Glucose, Addiction, and Rhythms
17 important questions on Glucose, Addiction, and Rhythms
Where is the maser biological clock located?
If the SCN is removed, all rhytm is lost.
Is the daily rhythm in basal plasma glucose levels dependent on feeding?
The highest levels of glucose are found at the time of awakening.
What does NMDA and Bicuccilline do?
- Bicucilline: blocks GABA action entrance in the PVN. So removes the inhibition of glutamate.
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Will there be an bicucullin effect at night?
GLU can have effect.
What happens after a SCN lesion?
How does GABA work? What is its effect?
How does the PVN stimulate the liver?
This was shown by cutting the para- and the sympathetic nerve. The sympathetic nerve was shown to be important, because without the bicucullin in PVN there was no increase in glucose.
What is the difference between homeostatic and hedonic?
Regulated by hypothalamus
- Hedonic: eating because you want something
Regulated by striatum
What are the types of glucose sensing neurons?
- Glucose excited (GE)
Which brain centers express glucose sensing neurons?
What does an glucose-sensing cell need?
2. Energy sensing enzymes
3. Transmembrane channels sensitive to changes in energy status
What do NPY/AgRP neurons do?
- NPY = Neuropeptide Y
AgRP = Agouti related peptide
- Increase food intake
- Are glucose inhibited (GI) neurons
What do POMC neurons do?
- alpha MSH is derived from POMC
- Located in hypothalamus, in the Arcuate Nucleus (Arc)
- Decreases food intake
- Are glucose excited (GE) neurons
How does the melanocortin (MC) system work?
- Md4R shows constitutive activity, thus in suppresses food intake
(when there is no MC4R there is no suppression, resulting in an obese phenotype)
- AgRP inhibits MC4R while alpha MSH stimulates MC4R.
How is dopamine linked to glucose metabolism?
- Produced in ventral tegmental area and substantia nigra
- 5 receptors: D1, D2, D3, D4, D5
The metabolism of glucose release dopamine, so the breakdown is actually needed for the reward system.
Mice: huge preference flavour conditioned with glucose vs flavour linked to non-metabolized glucose.
* Obese subjects have reduced dopamine binding.
To which brain parts has the ARC projections to?
LH: 'hunger center
VHM: saturation center
How is the nucleus accumbens (NAc) involved in glucose metabolism?
Dopamine system within NAc!
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