Corticoliberin and somatoliberin activity in the pituitary stalk median eminence of rats after neonatal treatment with monosodium glutamate

Neurotoxic lesions of the arcuate nucleus by neonatal treatment monosodium glutamate (MSG) resulted in a decrease of plasma GH levels without affecting plasma corticosterone concentration. The corticoliberin activity of the pituitary stalk median eminence (SME) in MSG-treated animals was similar to that of litter-mate controls. Growth hormone releasing (somatoliberin) activity of the SME, tested after placing an anterolateral cut around the medial basal hypothalamus, was significantly lower in MSG- treated than in control animals. It was concluded that the substantial proportion of the somatoliberin neurones are found in the arcuate nucleus.