RESUMO
Signals regulating diversification of olfactory sensory neurons to express odorant receptors and other genes necessary for correct assembly of the olfactory sensory map persist in the olfactory epithelium of adult mouse. We have screened for genes with an expression pattern correlating with the topography odorant receptor-expression zones. The Msx1 homeobox gene and a semaphorin receptor (Neuropilin-2) showed graded expression patterns in the olfactory epithelium. The gradients of Msx1 and Neuropilin-2 expression in basal cells and neurons, respectively, correlated with expression of a retinoic acid-synthesizing enzyme (RALDH2) in lamina propria. A BMP-type I receptor (Alk6) showed a reverse gradient of expression in the supporting cells of the epithelium. Considering known functions of identified genes in cell specification and axon guidance this suggests that zonal division of the olfactory sensory map is maintained, during continuous neurogenesis, as a consequence of topographic counter gradients of positional information.
Assuntos
Expressão Gênica/fisiologia , Cavidade Nasal/inervação , Cavidade Nasal/metabolismo , Neurônios Receptores Olfatórios/metabolismo , Proteínas Serina-Treonina Quinases , Receptores de Fatores de Crescimento , Fatores de Transcrição , Receptores de Ativinas Tipo I/biossíntese , Receptores de Ativinas Tipo I/genética , Aldeído Oxirredutases/biossíntese , Aldeído Oxirredutases/genética , Animais , Receptores de Proteínas Morfogenéticas Ósseas Tipo I , Proteínas de Homeodomínio/biossíntese , Proteínas de Homeodomínio/genética , Fator de Transcrição MSX1 , Camundongos , Camundongos Endogâmicos C57BL , Cavidade Nasal/citologia , Proteínas do Tecido Nervoso/biossíntese , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neuropilina-1 , Mucosa Olfatória/metabolismo , Retinal DesidrogenaseRESUMO
In the present study, the effects of the thiol oxidising agent diamide upon the properties of rat brain beta1-adrenergic and human platelet serotonin2A receptor recognition sites have been investigated using [3H](-)CGP-12177 (in the presence of ICI-118551) and [3H]LSD as ligands. (-)Isoprenaline inhibited [3H](-)CGP-12177 binding with nH values of 0.87, 0.67, and 0.56 for added Mg2+ concentrations of 0, 2.5, and 25 mM, respectively. Pretreatment with diamide increased the nH to above unity for the inhibition of the binding by (-)isoprenaline, without a concomitant effect on the inhibition of the binding by (-)propranolol. In contrast, diamide reduced the affinity of human platelet serotonin2A-receptors for antagonists, but did not consistently induce nH values above unity for the inhibition of antagonist binding by serotonin. These results suggest that cooperative interactions reported for cardiac muscarinic receptors may also occur for beta1-adrenergic receptors in the rat brain.
