Functional integration of the rat hippocampal tissue, transplanted into the rabbit septum.

摘要: Embryonal tissue of the rat hippocampus (E17-18) was grafted into small acute cavity within dorsal septum adult rabbit after interruption septo-hippocampal connections. Histological analysis (Nissl stain), performed 6-8 weeks later, revealed surviving hippocampal grafts in 14 out 29 animals (48%). Some were displaced ventricle and had only minor contact with host septum; some others, residing septum, separated from by continuous glial scar. Six (33%) morphologically well integrated septum. The contained mature pyramidal neurons but their organization layer absent. No signs rejection observed grafts, which not subjected to microelectrode investigation chronic conditions. for 5-9 successive days penetrated microelectrodes, heavily infiltrated lymphocytes necrotic areas. Electrophysiological testing absence spontaneous neuronal activity, or presence hypersynchronous epileptiform bursts isolated grafts. 4 investigated electrophysiologically, normal activity two types: low-frequency discharges complex spikes high-frequency single spikes, sometimes short periods weak rhythmic modulation theta-range. Characteristics xenografted are very close those described situ. Rhythmic theta-modulation appeared increased stability physostigmine injection host, electrical stimulation host's midbrain reticular formation ventral part diagonal band, multimodal sensory host. frequency theta-bursts identical that (4.5-6.5 Hz). Besides stimuli evoked tonic suppression activation discharges, phasic reactions on-effects. Electrical lateral band orthodromic antidromic cells. Normal cells deteriorated 5-11 investigation. It is concluded xenografts nervous tissue, developing without immunosuppression, have a low rate survival vulnerable immune response mechanical integrity blood-brain barrier. Nevertheless functional integration brain, apparently depending on development chimeric synapses, possible.