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

doi:10.1016/j.neuroscience.2006.10.015

Neuroscience

Volume 144, Issue 3, 9 February 2007, Pages 961-968

https://doi.org/10.1016/j.neuroscience.2006.10.015 Get rights and content

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.

Section snippets

Subjects

Subjects were Long-Evans hooded rats, descended from Simonsen Laboratory (Gilroy, CA, USA) stock and bred in the vivarium of the Department of Psychology at the University of Illinois. Pups were weaned at day 25, same-sex and litter-mate pair-housed, and handled once weekly thereafter until the time of kill. Food and water were available ad libitum; animals were maintained on a 12-h light/dark cycle with the lights on at 07:00 h. Subjects were examined at day 35 (peri-adolescent; females n=9,

Ventral mPFC

Total neuron number in the ventral mPFC decreased between days 35 and 90 (age: F=4.1, P<0.021). Although the interaction between sex and age was not significant, this effect was more pronounced in females (19% loss in females compared with just over a 5% loss in males), resulting in a sex difference in neuron number of this region in adulthood (females<males by approximately 13%, P<0.03) (Table 2). When the superficial and deep cortical layers of the ventral mPFC region were examined

Discussion

The present study investigated whether the number of neurons in the rat mPFC is altered between adolescence and young adulthood, and if so, whether these changes contribute to the sexual differentiation of this cortical region. We report that neuronal number is reduced in the ventral mPFC between postnatal days 35 and 90 in the rat, whereas glial cell number in this region remains stable during this time. Although we found that both sexes underwent a reduction in neurons, the effect was more

Acknowledgments

We thank Alexandra Santau, Beth Whitman, and Heidi Rosczyk for their assistance. This work was supported by NSF IBN 0136468 and a Woodrow Wilson, Johnson & Johnson Dissertation Fellowship to J.A.M. J.A.M. was supported by NIH HD07333.

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

Abstract

Section snippets

Subjects

Ventral mPFC

Discussion

Acknowledgments

Brain Res

Neuroscience

Biol Psychol

Neuroscience

Prog Neuropsychopharmacol Biol Psychiatry

Exp Neurol

Int J Psychophysiol

Brain Res Bull

Behav Brain Res

Neuropsychopharmacology

Brain Res Dev Brain Res

Brain Res Bull

Neurobiol Learn Mem

Behav Neural Biol

Neurosci Biobehav Rev

Trends Cogn Sci

Behav Brain Res

Neuroscience

Neonatal hippocampal damage in rats: long-term spatial memory deficits and associations with magnitude of hippocampal damage

Hippocampus

Age-related changes in frontal and temporal lobe volumes in men: a magnetic resonance imaging study

Arch Gen Psychiatry

Myelination of a key relay zone in the hippocampal formation occurs in the human brain during childhood, adolescence, and adulthood

Arch Gen Psychiatry

Synaptogenesis in the prefrontal cortex of rhesus monkeys

Cereb Cortex

Changes in regional cerebral blood flow during brain maturation in children and adolescents

J Nucl Med

Positron emission tomography study of human brain functional development

Ann Neurol

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