Integration of neocortical embryonal grafts with the neocortex of host rats examined by Leao's spreading cortical depression.
Cortical spreading depression (SD) was used to assess the density and organization of neural elements in neocortical transplants and their connectivity with the host brain. Embryonal neocortex (E14) was transplanted into cavities in the frontoparietal cortex of 3-month-old rats. SD elicited in the cortex of anesthetized host rats (n = 12) 3 to 8 months after transplantation did not penetrate into the grafts. SD could be elicited in large transplants but did not propagate to the surrounding host neocortex. Spontaneous unit activity in the transplants was affected by SD elicited in the neocortex of the host rats anesthetized with urethane. Most units (n = 49) displayed excitatory-inhibitory (52%) or inhibitory (29%) reactions, whereas purely excitatory reactions were less frequent (8%). The results suggest that the packing density of neurons in the transplant can support SD but that the conditions at the graft-host boundary (glial scar, scarcity of neurons) stop SD propagation. High reactivity of the graft neurons to SD in the host neocortex indicates that afferentation from the host brain represents an important, predominantly excitatory contribution to the spontaneous activity of the transplant.
Galik
J
J
Institute of Neurobiology, Slovak Academy of Sciences, Kosice.
Macias-Gonzalez
R
R
Valouskova
V
V
Bures
J
J
D000818:Animals; D016380:Brain Tissue Transplantation; D002540:Cerebral Cortex / Q000502:physiology*; D004594:Electrophysiology; D016332:Fetal Tissue Transplantation; D008297:Male; D051381:Rats