Postnatal increase of GABA- and PV-IR cells in the cerebral cortex of the lizard Podarcis hispanica.

The number and distribution of GABA- and parvalbumin (PV)-immunoreactive (IR) cells have been studied by immunocytochemistry in the cerebral cortex of newborn and adult lizards. The distribution of GABA-IR cells as well as that of PV-IR cells were similar in newborn and adult lizards, and PV-IR cells were GABA-IR in all cases. However, the absolute number of GABA- and PV-IR cells increased significantly during development. In addition, the rate of of GABA-IR cells also displaying PV immunoreactivity also increased after birth. Moreover, dendrites were rarely found to be PV-IR in newborn lizards, whereas they appeared stained in a Golgi-like manner in adult animals. These results suggest that the GABAergic neuronal population of the cerebral cortex of lizards experiments a significant increment in number and neurochemical maturation after birth.