Mental health 2

Question 1

Which 2 processes govern if youre asleep or awake?

Answer 1

sleep homeostatic drive

circadian clock

Question 2

What is sleep pressure?

Answer 2

how much pressure neurons feel before they trigger the sleep state

Question 3

What are circadian rhythms and what is there purpose?

Answer 3

Rhythms in physiology and behaviour generated by molecular clocks
purpose is to coordinate internal time with the external world

Question 4

Where is the master regulatory clock found and what does it do?

Answer 4

The suprachiasmatic nuclei of the hypothalamus

Maintains synchrony between all the molecular clocks of the body

Question 5

Which animal model helped us discover the circadian clock?

Answer 5

Drosophila

Question 6

What underlies the clock, what factors are involved ?

Answer 6

Cell autonomous transcription-translation feedback loops

CLOCK and BMAL1 drive the expression of PER1/2 and CRY 1/2, which go on to inhibit clock and bmal

Question 7

How does external light effect the clock?

Answer 7

Light activates the cry gene

Question 8

What evidence is there that the clock genes are involved in the developmental of mental disorders?

Answer 8

1. patients with neuropsychiatric disorders often exhibit sleep and circadian rhythm disruption
2. fibroblasts from schizo patients- loss of rhythmicity of cry1 and per1
3. also disrupted daytime expression of clock, per 1/2/3 and cry1
4. GWAS and snp analyses show a weak association between the core components of the clock with schizo, BPD and depression

Question 9

Circadian clock disruption and mental illness- cause or consequence?

Answer 9

Thought to be a bidirectional feedback loop with neuropsychiatric disease- changes in one exacerbate the dysfunction in the other

Question 10

What else does the understanding of the mechanisms behind the circadian clock help us with?

Answer 10

1. Help us understand the role of clock genes in many aspects of disease - including the metabolic syndrome
2. Melatonin as an antioxidant- failure to clear free radicals can cause mental and neurodegenerative diseases
3. chemotherapy- DNA repair optimised in the later afternoon, less at night

Question 11

What 3 antioxidant properties does melatonin have?

Answer 11

scavenging of free radicals
upregulation of antioxidant enzymes
direct inhibition of free radical formation

Question 12

Whats the link between the clock and DNA damage?

Answer 12

Thought that the clock evolved to help protect organisms againt UV induced DNA damage - thus the oscillation in expression of the molecules involved in DNA repair