Neuron number decreases in the rat ventral, but not dorsal, medial prefrontal cortex between adolescence and adulthood

• Published in: Neuroscience Vol. 144; no. 3; pp. 961 - 968
• Main Authors: Markham, J.A, Morris, J.R, Juraska, J.M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 09.02.2007; Elsevier
• Subjects: Aging - physiology; Animals; anterior cingulate; Biological and medical sciences; Cell Count; Cell Death - physiology; Cell Proliferation; cortical volume; development; Environment; Female; Fundamental and applied biological sciences. Psychology; Male; Nerve Fibers, Myelinated - physiology; Neuroglia - cytology; Neuroglia - physiology; Neurology; Neuronal Plasticity - physiology; Neurons - cytology; Neurons - physiology; Prefrontal Cortex - cytology; Prefrontal Cortex - growth & development; Rats; Rats, Long-Evans; Sex Characteristics; sex differences; Vertebrates: nervous system and sense organs; white matter; ventral anterior cingulate cortex; development; ACd; CE; IL; medial prefrontal cortex; prelimbic cortex; infralimbic cortex; medial precentral cortex; Fr2; cortical volume; coefficient of error; PrCm; frontal cortex, area 2; dorsal anterior cingulate cortex; white matter; mPFC; ACv; anterior cingulate; PL; sex differences; Rat; Rodentia; Central nervous system; Sex; Prefrontal cortex; White matter; Encephalon; Vertebrata; Mammalia; Neuron; Animal; Development
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2006.10.015

Abstract Neuroimaging studies have established that there are losses in the volume of gray matter in certain cortical regions between adolescence and adulthood, with changes in the prefrontal cortex being particularly dramatic. Previous work from our laboratory has demonstrated that cell death can occur as late as the fourth postnatal week in the rat cerebral cortex. The present study examined the possibility that neuronal loss may occur between adolescence and adulthood in the rat prefrontal cortex. Rats of both sexes were examined during adolescence (at day 35) and young adulthood (at day 90). The volume, neuronal number, and glial number of the medial prefrontal cortex (mPFC) were quantified using unbiased stereological techniques. Neurons were lost from the ventral, but not dorsal, mPFC between adolescence and adulthood, suggesting a late wave of apoptosis that was region-specific. This was accompanied by a decrease in the volume of the female ventral mPFC. In contrast to neuron number, the number of glial cells was stable in the ventral mPFC and increased between adolescence and adulthood in the dorsal mPFC. Sex-specific developmental changes in neuron number, glial number, and volume resulted in sex differences in adults that were not seen during adolescence. The loss of neurons at this time may make the peri-adolescent prefrontal cortex particularly susceptible to the influence of environmental factors.