Neonatal
monosodium glutamate (
MSG) treatment has been associated with dysfunctions in stress responses. Therefore, the present study aimed at examining the acoustic startle response (ASR) in
MSG-treated rats and the effects of fetal neural
transplantation. Male and female rats were given
MSG (4 mg/g) or saline on alternate days from days 2-10 after birth. To determine whether fetal transplants could reverse behavioral impairments observed in
MSG-treated rats, at 12 days of age
MSG-treated rats received either arcuate nucleus (AN), cortical fetal grafts, or
sham surgery into the third ventricle. ASR amplitude was measured at 35-40 days of age, and again in adulthood.
MSG produced the expected decrease in the density of hypothalamic
neuropeptide Y (NPY) and
tyrosine hydroxylase (TH) in the AN area.
Corticotropin-releasing factor (CRF) neurons/fibers were not affected by
MSG. Pituitary
atrophy was observed in all
MSG rats. We report a permanent increase in the amplitude and reduction in short-term habituation of ASR in all
MSG-treated rats. No effect was observed on long-term habituation in male rats. Cortical, but not AN tissue significantly reduced the magnitude of ASR in
MSG animals. The results are discussed in terms of the central pathways mediating ASR, in particular hypothalamo-amygdala connections. It is considered that nonspecific factors mediate recovery produced by cortical tissue grafts, as observed in other models of neural
transplantation.