Transplanted septal neurons make viable cholinergic synapses with a host hippocampus.
Cell suspensions from the fetal septal region were injected stereotaxically into the hippocampus of fornix-fimbria-transected adult rats. The host rats were sacrificed up to 3 months after the operation and the hippocampus sliced into 350 microns transverse slices. Intracellular recording was made from CA1 neurons adjacent to the graft. Electrical stimulation of the graft produced a voltage-dependent depolarization in some recorded neurons. This was associated with an increase in spontaneous and anodal break action potential discharges. In addition, a slow after-hyperpolarization (AHP) which typically follows a burst discharge was blocked during the depolarization indicating that the stimulation may block a Ca2+-dependent K+ current. The effects of the stimulation were antagonized by atropine. A response to the stimulation was seen 2 weeks but not 1 week after grafting. Over time, cells that were located away from the graft became activated by the stimulation. This was correlated with the extent of proliferation of acetylcholinesterase-containing fibers around the graft. These results suggest that grafted septal neurons make viable cholinergic connections with a host hippocampus.
D000110:Acetylcholinesterase / Q000032:analysis; D000818:Animals; D002799:Cholinergic Fibers / Q000254:growth & development*; D004594:Electrophysiology; D006085:Graft Survival; D006624:Hippocampus / Q000032:analysis / Q000502:physiology*; D006651:Histocytochemistry; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000637:transplantation*; D051381:Rats; D011919:Rats, Inbred Strains; D012688:Septum Pellucidum / Q000637:transplantation*; D013569:Synapses / Q000502:physiology*
D000110:Acetylcholinesterase