Inhibitory interneurons in the anterior cingulate and medial prefrontal cortex in prenatally malnourished rats

Prenatal protein malnutrition continues to be a significant problem in the world today. Exposure to prenatal protein malnutrition increases the risk of a number of neuropsychiatric disorders that are associated with inhibitory interneurons, including depression, schizophrenia and attention deficit hyperactivity disorder. Previous studies have found that neurons in anterior cingulate and medial prefrontal regions respond excessively to restraint stress in prenatally malnourished rats. In this study, we investigate if prenatal protein malnutrition affects inhibitory the subpopulation of interneurons in the prefrontal cortex in relationship to the higher initial stress response. This was done using double-labeling immunohistochemistry with c-Fos to mark activated neurons and parvalbumin to mark inhibitory interneurons. Numbers of single and double-labeled neurons were quantified with unbiased stereology. Statistical analysis demonstrated that there was no effect of prenatal malnutrition on the total number of neurons or on the number of parvalbumin neurons. However, prenatal malnutrition was associated with a significant increase in the number of inhibitory parvalbumin positive neurons activated by restraint stress. This suggests that prenatal malnutrition altered the excitability of these inhibitory interneurons either directly or by altering their connectivity