XB-ART-42486Eur J Neurosci December 1, 2010; 32 (12): 2082-6.
Plasticity of melanotrope cell regulations in Xenopus laevis.
This review focuses on the plasticity of the regulation of a particular neuroendocrine transducer cell, the melanotrope cell in the pituitary pars intermedia of the amphibian Xenopus laevis. This cell type is a suitable model to study the relationship between various external regulatory inputs and the secretion of an adaptive endocrine message, in this case the release of α-melanophore-stimulating hormone, which activates skin melanophores to darken when the animal is placed on a dark background. Information about the environmental conditions is processed by various brain centres, in the hypothalamus and elsewhere, that eventually control the activity of the melanotrope cell regarding hormone production and secretion. The review discusses the roles of these hypothalamic and extrahypothalamic nuclei, their neurochemical messengers acting on the melanotrope, and the external stimuli they mediate to control melanotrope cell functioning.
PubMed ID: 21143662
Article link: Eur J Neurosci
Species referenced: Xenopus laevis
Genes referenced: adcyap1 avp bdnf crh myh3 npy pomc sri tbx2 ucn1
Article Images: [+] show captions
|Fig. 1. Schematic view of brain centres, pathways and neurochemical messengers inhibiting and stimulating melanotrope cells in the pars intermedia (PI) of the pituitary gland of Xenopus laevis. 5-HT, serotonin; ACh, acetylcholine; AVT, arginine-vasotocin; BDNF, brain-derived neurotrophic factor; CRF, corticotropin-releasing factor; DA, dopamine, GABA, c-aminobutyric acid; LC, locus ceruleus; MCN, magnocellular nucleus; ME, metenkephalin; MT, mesotocin; NA, noradrenaline; NPY, neuropeptide Y; PACAP, pituitary adenylate cyclase-activating polypeptide; PN, pars nervosa, PD, pars distalis; RN, raphe nucleus; SCN, suprachiasmatic nucleus; Ucn1, urocortin-1. Modified after Kramer (2002), courtesy of R. Tuinhof.|
|Fig. 2. Electron micrographs of the pars nervosa of the pituitary gland of Xenopus laevis. (A) Survey of neurohemal axon terminals (T) filled with secretory granules, near a capillary with erythrocyte (E). P, pituicyte. Scale bar = 2 lm. (B) Type 1 terminal (1) with large, round secretory granules, and type 5 terminal (5) with rather small and pleomorphic secretory granules (classification after Van Wijk et al., 2010). Scale bar = 250 nm. (C) Immunogold electron microscopy showing arginine-vasotocin-immunoreactive secretory granules in type 1 terminal. Scale bar = 100 nm.|