The medial preoptic area (MPOA), bed nucleus of the stria terminalis (BNST), and medial amygdaloid nucleus (Me) are essential for male sexual behavior in the Syrian hamster. These nuclei received chemosensory stimuli and gonadal steroid signals, both of which are required for mating behavior. The objective of this study was to compare the distribution of androgen- and estrogen-concentrating neurons in MPOA, BNST, and Me in the adult male hamster using steroid autoradiography for estradiol (E2), testosterone (T) and dihydrotestosterone (DHT). Adult males (n = 4 per group) received two i.p. injections of tritiated steroid 4-7 days after castration. Six-microns frozen sections through the brain were mounted onto emulsion-coated slides, and exposed for 11-16 months. In MPOA, BNST, and Me, neurons were more abundant and heavily labelled after [3H]E2 treatment than after either [3H]T or [3H]DHT. Tritiated estradiol- and DHT-labeled cells were found throughout the rostrocaudal extent of Me, with a high concentration in posterodorsal Me. Tritiated testosterone treatment labelled cells largely within posterodorsal Me. In MPOA, the majority of E2-, T-, and DHT-labelled neurons were in the medial preoptic nucleus (MPN) and the preoptic continuation of the posteromedial bed nucleus of the stria terminalis (BNSTpm). Few T-labelled cells were present outside these subdivisions. In the BNST, E2- and DHT-labelled neurons were present in all subdivisions, whereas T labelling was confined to the antero- and posteromedial subdivisions of BNST. These results suggest that the distribution of androgen- and estrogen receptor-containing neurons overlap considerably in nuclei which transmit chemosensory signals in the control of mating behavior.
Three fluorescein-labeled lectins have been shown to exhibit specificity for the surface of cells in different layers of the epidermis in the newborn rat. An isolectin from seeds of Bandeiraea simplicifolia with specificity for a-D-galactosyl end groups labeled the basal and lower spinous cells; a lectin from Ulex europaeus exhibiting specificity for a-L-fucosyl units outlines the surface of spinous cells, and a second lectin from B. simplicifolia, with specificity for N-acetyl-Dglucosamine, labels the cornified cells. Appropriate blocking experiments have confirmed the specific nature of the binding.The investigation of the differentiative process in mammalian epidermis would be assisted by the availability of a technique that would specifically identify different strata. Lectins, which have an affinity for specific sugars (cf. refs. 1 and 2), have been used to probe the nature of the complex carbohydrates associated with cell surfaces (cf. ref.3) and to investigate the role of the cell surface in cellular functions such as growth (4, 5), adhesion (6), pinocytosis (7), antigenicity (8), fertilization (9), and differentiation (10).It seemed possible that specific lectins could be found that would associate with the cell surface during various stages of epidermal differentiation if changes in surface carbohydrates, occurred during this process. Fluorescein-labeled concanavalin A attaches to the surfaces of cells in all layers of the human epidermis (11) and oral mucosa (12) except the stratum corneum. The pattern of binding for concanavalin A and pemphigus antibody are similar (13); however, there are differences in the binding of lectins to the cell surface of carcinomas and wounds in the human oral epithelium (14). In the normal oral mucosa (15), human epidermis (16), and gastrointestinal mucosa of the rat (17, 18), keratinocytes in different differentiative stages exhibit specificity for the binding of particular lectins to their surfaces. The loss of the nucleus from differentiating erythrocytes of the rat results in a change in the labeling of the surface by concanavalin A (10).Three lectins have now been identified that do exhibit specificity for the surface of cells in different layers of the epidermis in the newborn rat. One lectin, with specificity for a-D-galactosyl groups, binds to basal and lower spinous cells; another, specific for a-L-fucosyl units, outlines spinous cells, and the third, specific for N-acetyl-D-glucosamine, labels cornified cells. FITC-Ulex I was diluted to 125-150 g/ml. As controls, Lfucose (Sigma) or N-acetyl-D-glucosamine (Aldrich) at a concentration of 0.5 M in phosphate-buffered saline was preincubated with the lectin. Dorsal skin from newborn rats (CFN strain) was stretched over the surface of a watch glass and frozen to -30'C. Small strips (3 mm X 5 mm) were subsequently cut with a scalpel and set into Tissue-Tek II O.C.T. embedding medium (Miles Laboratories, Naperville, IL), exposing a cross section of skin. Sections were cut 4-6 Mm thick in a cryostat and placed o...
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