Immunocytochemical localization of POMC-derived peptides (adrenocorticotropic hormone, alpha-melanocyte-stimulating hormone and beta-endorphin) in the pituitary, brain and olfactory epithelium of the frog, Rana esculenta, during development.
Developmental stages of Rana esculenta, starting with the posterior limb-bud stage (stage 26) up to a few days after metamorphosis, were examined immunohistochemically to localize cells and fibers producing some POMC-derived peptides, namely, alpha-MSH, ACTH and beta-END. Anti ACTH and anti alpha-MSH revealed a positive reaction in the pars intermedia during all stages of development included in this study, whereas no immunoreactivity in this pituitary zone was ever evidenced with anti beta-END. In the pars distalis strongly positive cells were seen with anti ACTH and anti beta-END, while anti alpha-MSH yielded weakly positive cells. Interestingly, these peptides were colocalized in the same cells. Immunoreactivity for alpha-MSH was no longer present in the pars distalis during metamorphic climax and postmetamorphosis. In the brain of premetamorphic tadpoles, belonging to stages 26 to 30, a few neurons in the posterior telencephalon showed a positive reaction only with anti alpha-MSH, but from stage 31 (prometamorphosis) onwards, ACTH and beta-endorphin-like peptide producing cells, together with alpha-MSH-immunoreactive cells, were seen in this region and in the anterior preoptic area and infundibulum. This situation persisted in the subsequent stages of development. Anti alpha-MSH also revealed weakly positive cells in the olfactory epithelium in premetamorphic tadpoles; strong immunoreactivity with anti alpha-MSH was seen in olfactory epithelium cells in animals during prometamorphosis, metamorphic climax and postmetamorphosis. The possible significance of these findings is briefly discussed.
Department of Zoology, University of Naples, Italy.
B
B
D'Aniello
C
C
Imperatore
M
M
Fiorentino
M
M
Vallarino
R K
RK
Rastogi
D000324:Adrenocorticotropic Hormone / Q000032:analysis*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D007814:Larva; D008675:Metamorphosis, Biological; D009831:Olfactory Mucosa / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D011893:Rana esculenta / Q000378:metabolism*; D000521:alpha-MSH / Q000032:analysis*; D001615:beta-Endorphin / Q000032:analysis*
D000521:alpha-MSH; D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone