Results of morphometric study of ultrastructure of axosomatic and axospinous synapses of rat sensomotor neocortex after DSIP administration and in hypoxia showed that the peptide administration resulted in multidirectional changes in these type contacts in intact animals. This, apparently, is connected with their different functional specialization. Preliminary DSIP administration prevented changes, appearing in hypoxia in most of the parameters studied both in axosomatic and axospinous synapses.