POSTNATAL INCREASE OF GABA- AND PV-IR CELLS IN THE CEREBRAL-CORTEX OFTHE LIZARD PODARCIS-HISPANICA

The number and distribution of GABA- and parvalbumin (PV)-immunoreacti ve (IR) cells have been studied by immunocytochemistry in the cerebral cortex of newborn and adult lizards. The distribution of GABA-IR cell s as well as that of PV-IR cells were similar in newborn and adult liz ards, and PV-IR cells were GABA-IR in all cases. However, the absolute number of GABA- and PV-IR cells increased significantly during develo pment. In addition, the rate of of GABA-IR cells also displaying PV im munoreactivity also increased after birth. Moreover, dendrites were ra rely found to be PV-IR in newborn lizards, whereas they appeared stain ed in a Golgi-like manner in adult animals. These results suggest that the GABAergic neuronal population of the cerebral cortex of lizards e xperiments a significant increment in number and neurochemical maturat ion after birth.