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At this point three brain centres are thought to be involved in the regulation of the melanotrope cells of the pituitary pars intermedia of Xenopus laevis: the magnocellular nucleus, the suprachiasmatic nucleus and the locus coeruleus. This study aims to investigate the existence of a fourth, serotonergic, centre controlling the melanotrope cells. In-vitro(More)
The melanotrope cell of Xenopus laevis is innervated by nerve terminals that contain, among other transmitter substances, the neurotransmitter gamma-aminobutyric acid (GABA). Postsynaptically the melanotrope cell possess both GABAA and GABAB receptors. Activation of either receptor type leads to an inhibition of alpha MSH release from the cell. The present(More)
The enzyme adenylyl cyclase from sheep olfactory epithelium is dually regulated by GTP and is highly sensitive to the nucleotide analogues GTPγS and GppNHp, as well as to fluoride ions and forskolin. Many, but not all, odorants tested are able to stimulate adenylyl cyclase in a dose-dependent manner and with different potencies. Such an effect is detectable(More)
Previous studies have focused on the immunohistochemical detection of a nitric oxide (NO)-cyclic 3',5'-monophosphate (cGMP) pathway in the brain and pituitary of the aquatic toad Xenopus laevis. We here investigate the endogenous production and possible involvement of NO signaling in the regulation of melanotrope cell activity in the pituitary pars(More)
Sheep olfactory epithelium contains an adenylyl cyclase which is stimulated by many but not all odorants. Here we report that this enzyme is activated by calmodulin in a dose-dependent manner, and that calcium ions are required for this response. Odorant stimulation of adenylyl cyclase is unaffected by the complex Ca2+/calmodulin, as suggested by the(More)
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