Postnatal maturation of prefrontal pyramidal neurones is sensitive to a single early dose of methamphetamine in gerbils (Meriones unguiculatus)

The effect of a single methamphetamine application on postnatal maturation of the prefrontal cortex was studied using pyramidal cell morphology and spine density as parameters of systemic plasticity. Male gerbils were injected a single dose of methamphetamine (METH, 50 mg/kg, i.p.) on postnatal day 14. On postnatal day 90, prefrontal cortices of METH-treated animals and saline-treated controls were processed for Golgi-staining. Dendritic arbours of layer III and V pyramidal neurones were measured to describe pyramidal cell morphology, and segmental spine counts were carried out. The results showed that a single postnatal METH-challenge significantly alters morphological differentiation of pyramidal cells towards adulthood. Cells from METH-treated animals showed a higher total dendritic length based on longer segments between subsequent dendritic branchings, with only the apical stem dendrite being shorter in METH-treated than in control subjects. The branching rate was slightly but not significantly increased in METH-treated animals. Nevertheless, spine density was significantly increased on all types of dendrites, with apical dendrites of both layers III and V showing the highest drug-induced progression of about 50% compared to control values. The present results are discussed with regard to probable clues they may provide for investigating neurobiological principles of psychotic behaviour in an animal model.