Lecture 5- How do Clock Cells Talk

Question 1

What indicates that the SCN depends on intracellular communication

Answer 1

The fact that the SCN contains synchronised high amplitude rhythms and desynchronised low amplitude rhythms

Question 2

AVP (vasopressin)
location of receptor expression

location of AVP neurons within the SCN

Answer 2

V1a and V1b are expressed in the SCN, with AVP neurons being more prevalent along the medial aspect of the SCN (in shell)

Question 3

What kind of receptors are neuropeptide receptors?

Answer 3

GPCRs

Question 4

Mice lacking in V1a and V1b receptors are

Answer 4

resistant to jet lag; can re-entrain much better than WT; rapidly phase shift w changes in LD; do not show transient re-entrainment

Question 5

IN AVP receptor KO mice, PER gene expression

Answer 5

is reset ~half the time of WT

Question 6

Clock gene expression in both liver and SCN of V1a/b KOs mice

Answer 6

phase shift rapidly with LD changes i

Question 7

AVP receptor mice KO considerations

Answer 7

could be because these mice have developed without these key receptors, however pharmacological blockade mimics AVP KO effects making this unlikely

Question 8

AVP signalling (via V1a and V1b receptors) on the circadian system

Answer 8

ordinarily act as an intrinsic brake on the circadian system to control the rate of re-entrainment, interneural signalling between cells of the SCN normally acts to resist external perturbation on the clock

Question 9

Jet lag

Answer 9

recovery is about 1 hour per day, harder for the clock to go phase advance than it is delay

Question 10

VIP (expression)

Answer 10

is abundant in the SCN near OX

Question 11

VPAC2

Answer 11

also heavily expressed in the SCN

Question 12

VIP-VPAC2 signalling

Answer 12

has been implicated in the photic entrainment of the SCN via RHT

Question 13

VIPR2 KO mice

Answer 13

have significantly disrupted wheel running behaviours and almost completely non-existent phasic firing w zeitgeber time, and have a disorganised molecular clock

Question 14

Pharmacological blockade of VIPR2

Answer 14

prevents peaking in firing rate rhythm (but rhythms are rescued as antagonist washes out)

Question 15

In the absence of VIP-VPR2 signalling

Answer 15

both amplitude and synchrony are impaired in SCN neurons

Question 16

VIP and VIPR2 KO mice

Answer 16

are behaviourally arrhythmic, or express accelerated behavioural rhythms

Question 17

In vitro, VIPR2 KO neurons

Answer 17

show dampened firing and appear arrhythmic

Question 18

VIPR2 SCN cannot

Answer 18

gate the actions of light on the P-ERK pathway

Question 19

Insect correlate of VIP

Answer 19

PDF

Question 20

PDF is analogous to

Answer 20

PDH, but lacks a chromatophore

Question 21

PDF is found in

Answer 21

SLNvs and LLNvs

Question 22

PDF signalling takes place via

Answer 22

the PDFR receptor, a B1 class GPCR, +vely coupled to adenylate cyclase

Question 23

PDF KO flies

Answer 23

show disrupted circadian rhythms, lacking morning anticipation and advancement in evening anticipation

Question 24

PDF and PDFR mutants also show

Answer 24

a marked decrease in rhythm amplitude in DD or may even be arryhthmic

Question 25

PDF has complex actions that may differ between clock cells

Answer 25

may lengthen or shorten the period of a clock cell

Question 26

PDF has mixed function in neurons

Answer 26

in some PDF signal is needed to synchronise the clock, in others it is needed for clock cycling

Question 27

number of VIP neurons in humans

Answer 27

decrease with age

Question 28

In PD

Answer 28

the number of VIP and AVP neurons are greatly reduced

Question 29

Genetic mutations in the VIPR2 gene

Answer 29

is linked to increase risk of developing schizophrenia

Question 30

Scheduled exercise

Answer 30

can restore rhythms in VIPR2 KO mice