Using two-dimensional gel electrophoresis and a highly sensitive silver stain, specific proteins in adult male and female rat brain were examined. Based on previous studies, the preoptic medial nucleus (POM) of the hypothalamus served as the area of interest, with the parietal cortex acting as control. A significant difference between the sexes was found in the concentration of two proteins in the POM, a difference which was not found in the parietal cortex.
The location of the enzymes neuron-specific enolase and nonneuronal enolase on two-dimensional gels generated from tissue samples obtained from fresh human and rat cortex has been identified. This identification is based upon the following criteria: (1) comigration on polyacrylamide gels with the appropriate purified protein and (2) staining on nitrocellulose protein blots of human
The arcuate nucleus-median eminence complex (AM) undergoes major structural and functional changes during normal puberty or if exposed to a pulse of estradiol in the prepuberal period. Those changes are expressed by increased synaptogenesis and by a drastic alteration in the feedback control of anterior pituitary gland hormone release. In this study we investigated the effects of estradiol benzoate (EB) on specific proteins in this hypothalamic area. Prepuberal, 25-day-old female rats were administered 10 µg of EB s.c. in oil or sesame oil vehicle. The animals were decapitated either 17 or 42 h after treatment. The brains were removed, blocked and serially sections at 300 µm using a Vibratome. The AM was dissected out and incubated for 6 h in a medium containing 35S-methionine and 35S-cysteine. Proteins from the AM were separated by two-dimensional gel electrophoresis, and the gels were exposed to X-ray film. The resulting autofluorographs were analyzed by scanning densitometry. The results show that the incorporation of labeled amino acids was increased in 10 proteins and decreased in 2 proteins in rats killed 17 h after EB. At 42 h after EB, 6 proteins showed an increased incorporation of amino acids and two proteins showed a decrease. Our results suggest that one or several of these proteins might be involved in the neuroendocrine and structural changes observed in the AM during puberty.
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