DISTRIBUTION OF PARVALBUMIN IMMUNOREACTIVITY IN THE NEOCORTEX OF HYPOTHYROID ADULT-RATS

Early hypothyroidism produces a generalized damage in the brain and in particular, changes in the connectivity of neocortical sensory areas. In this paper, the potential alterations in local neocortical circuit s have been explored using immunocytochemistry for parvalbumin (PV) in normal and hypothyroid adult rats. The number and radial distribution of PV-positive cells were similar in both groups, but in hypothyroid rats, the density of PV-positive terminal-like puncta and processes wa s dramatically reduced, especially in layers II-III and the lower part of layers IV-V and VI. These results suggest that thyroid hormones ar e necessary for normal development of cortical circuits in which PV-po sitive cells are involved.