Wistar rats with different levels of resistance to emotional stress (ES) were subjected to stress and brain sections stained with Nissl cresyl violet were used for quantitative analysis of the structural organization of neurons in layer V of the sensorimotor cortex. Some animals received delta sleep-inducing peptide (DSIP) 1 h before stress. Control ES-susceptible rats, as compared with resistant rats, had lower levels of normochromic and moderately hypochromic neurons. Normochromic neurons were not seen after stress. Rats susceptible to ES showed particularly sharp decreases in moderately hypo- and hyperchromic neurons, along with increases in the proportions of extremely hypo- and hyperchromic neurons, ghost cells, and ischemically altered cells. After administration of DSIP before stress, ischemically altered cells were not seen in any group: the level of reduction of extremely hyperchromic neurons was smaller in ES-susceptible rats than in ES-resistant rats. It is suggested that brain hypoxia plays a particular role in disorganizing the cortex in conditions of ES, while DSIP has both antistress and antihypoxic properties.