LOSS OF GAMMA-AMINOBUTYRIC-ACID (GABA) IMMUNOREACTIVITY FROM MOUSE 1ST SOMATOSENSORY (SI) CORTEX FOLLOWING NEONATAL, BUT NOT ADULT, DENERVATION

Whisker follicles were surgically ablated (lesioned) on two entire rows (B and C) of the left snout of two groups of Swiss mice, in the first 2 days after birth, and in the second group at 8 weeks of age (adults). Two months after surgery GABA-immunoreactivity (GABA-IR) was examined in tangential sections of the first somatosensory (SI) 'barrel' cortex of these two groups (at which time it was also confirmed that the follicles had not regrown). In the adult-lesioned mice all of the barrels appeared intact and visually similar in both the experimental (right) and control (left) hemispheres. The staining pattern of immunopositive cells and puncta was qualitatively similar to that which we have described previously 2. However, in the neonatally-lesioned mice barrel rows B and C were not visible in the right hemisphere sections and there was a marked reduction in GABA-IR, with fewer immunopositive cells. Many of those that did show GABA-IR stained only weakly and the puncta were also fewer in number than in the left (control) hemisphere where the GABA-IR pattern and staining intensity was normal.