Lecture 12 - Neural Repair

Question 1

What is axotomy?

Answer 1

damage to the axon by cutting or crushing

Question 1

What does axotomy affect?

Answer 1

the injured neuron and its synaptic partners

Question 2

What happens to the injured neuron after axotomy?

Answer 2

it begins to degenrate myelin fragments and the terminal degenerates and synaptic inputs retract

Question 3

What happens in wlds mutant mice?

Answer 3

axon degeneration is delayed and axonal degeneration after injury is usually immediate but in the wlds mutant it is delayed and this shwos that degenration is an actuve process which can be delayed or interrupted

Question 4

What axons regenerate better those in the peirphery or those in the CNS?

Answer 4

axons in the periphery regenerate better than those in the CNS

Question 5

What happens after axotomy in the PNS?

Answer 5

the proximal stump becomes a neurite and via schwann cells is gided to it muscle target

Question 6

What happens after axotomy in the PNS?

Answer 6

a glial scar forms which is due to infilitration of glial cells which inhibit neurite outgrowth and axonal regenration

Question 7

ARE CNS NEURONS INTRINSICALLY UNABLE TO REGROW OR DOES THE ENVIRONEMNT OF THE CENTRAL NERVOUS SYSTEM INHIBIT GROWTH?

Answer 7

BOTH

Question 8

IF YOU TRANSCAT THE SPINAL CORD AND GRAFT IN THE SCIATIC NERVE WHAT HAPPENS?

Answer 8

YOU SEE MORE ROBUST REGENERATION FOR BOTH ASCEDNING AND DESCENDING NEURONS

Question 9

WHAT HAPPENS IF YOU INSERT THE OPTIC NERVE INTO THE PERIPEHRY?

Answer 9

GET NO REGENRATION IN THE PERIPHERY AND THE CENTRAL ENVIRONMENT INHIBITS IT

Question 10

WHAT DOES THE INSERTION OF PNS NERVE SECTION INTO THE CNS NERVE PROMOTING REGENERATION SHOW?

Answer 10

THERE ARE FACTORS IN THE PERIPHERAL ENVIURONEMNT THAT PROMOTE OR INHIBIT CAPACITY TO REGENRATE

Question 11

WHY HAVE MATURE MAMMALS LOST THE IMPORTANT CAPACITY FOR REPAIR AND REGENERATION IN THE CNS?

Answer 11

WE HAVE THE CAPACITY TO REMODEL THE BASIC WIRING OF OUR BRAIN IN ACCORDANCE WITH EXPERIENCE DURING CP IN DEVELOPMENT
-SO OUR BRAIN ARE OPTIMIZED FOR OUR ENVIRONEMNT HOWEVER ONCE THIS REMODELING HAS OCCURRED IT MUST BE STABILIZED
-WE NEED TO MAINTAIN CONSTANCY IN THE FACE OF SMALL PERTURBATIONS IN CONNECTIVTIY WHICH LIMITS THE ABILITY OF CENTRAL CONNECTIONS TO REGENERATE IN RESPONSE TO INJURY AND THIS IS THE FAUSTIAN BARGAIN WE HAVE MADE FOR THE POSSESSION OF MANY PRECISELY WIRED CIRCUITS THAT UNDERLIE OUR SUPERIOR INTELLECTUAL POWERS

Question 12

WHAT ARE THE EXTRINSIC SIGNALING PATHWAYS WHICH INBHIBIT AXON REGENATION IN THE OPTIC NERVE?

Answer 12

SOCS3 - IN ECF OF CNS
MYELIN AND MYELIN GLIAL DERIVED FACTORS

Question 13

WHAT DOES SOCS3 BIND TO WHCIH PREVENT CNTF FROM BINDING TO IT PREVENTING REGENERATION?

Answer 13

GP130

Question 14

WHAT WAS SEEN IN A SOCS3 MUTANT?

Answer 14

COULD GET MORE REGENRRATION

Question 15

WHAT WAS SEEN IF YOU ADD MORE CNTF IN SOCS3 MUTANT WHAT HAPPEN?

Answer 15

COULD PROMOTE SOME REGENERATION

Question 16

IF YOU KO SOCS3 AND GP130 WHAT HAPPENS?

Answer 16

NO REGENRATION

Question 17

HOW CAN MYELIN INHIBIT CENTRAL AXON REGENRATION?

Question 18

HOW DO SENSORY FIBERS NORMALLY EXTEND?

Answer 18

ROSTRALLY IN A MYELIN RICH SPINAL CORD

Question 19

IF YOU SECTION THE SENSORY NEURONS IN DRG WHAT HAPPENS?

Answer 19

ACONS DEGENRATE WHICH LEAVES A PROTION OF SPINAL CORD DENERVATED

Question 20

IF YOU USE RADIATION OT BLOCK MYELINATION CAUSE GLIAL CELLS ARE DIVIDING AND NEURONS ARE NOT WHAT HAPPENS?

Answer 20

SENSORY NEURONS THAT ENETERS THE CORD THROUGH NEIGHBORINH UNINJURED TOOTS SPROUT NEW AXONS

Question 21

WHAT ARE THE MYELIN AND GLIAL SCAR COMPONENTS THAT INHIBIT CNS REGENRATION?

Answer 21

NOGO, OMGP, MAG

Question 22

WHAT DO THE MYELIN AND GLIAL SCAR COMPONENTS NOGO, OMgp, and MAG do?

Answer 22

bind to nogo receptor whcih assoiates with p75 deathe rceptor and ig protein pirb

Question 23

What is secreted by a reactibve astricyte when forming the glial scar?

Answer 23

cspg ibinds tio ptp sigman and inhibits regowth