Expression and physiological regulation of BDNF receptors in the neuroendocrine melanotrope cell of Xenopus laevis.
Brain-derived neurotrophic factor (BDNF) and alpha-melanophore-stimulating hormone (alpha-MSH) are co-sequestered in secretory granules in melanotrope cells of the pituitary pars intermedia of the amphibian Xenopus laevis. alpha-MSH is responsible for pigment dispersion in dermal melanophores during the process of black-background adaptation. BDNF-production in melanotrope cells is increased by placing animals on a black background, and BDNF acts as an autocrine stimulatory factor on the melanotrope cells. However, the repertoire of possible neurotrophin receptors of the melanotrope is unknown. In this study we have established the expression of full length TrkB (TrkB.FL), truncated TrkB (TrkB.T) and p75(NTR) receptors in the Xenopus neurointermediate lobe by RT-PCR. In situ hybridization reveals the presence of TrkB.FL mRNA and p75(NTR) mRNA in melanotrope cells. Quantitative RT-PCR shows that in animals on a black background the amounts of TrkB.T and p75(NTR) mRNA are about three times higher than in white background-adapted animals. We suggest that the amount of p75(NTR) sets the sensitivity of the melanotrope cells for the stimulatory action of BDNF during physiological adaptation to background light intensity.
Kidane
Adhanet H
AH
Department of Cellular Animal Physiology, Integrative Physiology, EURON European Graduate School of Neuroscience, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
van Dooren
Sander H J
SH
Roubos
Eric W
EW
Jenks
Bruce G
BG
D000220:Adaptation, Biological / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D005786:Gene Expression Regulation; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D052717:Melanotrophs / Q000378:metabolism* / Q000502:physiology*; D008969:Molecular Sequence Data; D020800:Receptor, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism; D020813:Receptor, trkB / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012879:Skin Physiological Phenomena / Q000235:genetics; D012880:Skin Pigmentation / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics*
D007527:Isoenzymes; D020800:Receptor, Nerve Growth Factor; D020813:Receptor, trkB