Comparative analysis of monoaminergic cerebrospinal fluid‐contacting cells in Osteichthyes (bony vertebrates) |
| |
Authors: | Anna L Xavier Romain Fontaine Solal Bloch Pierre Affaticati Arnim Jenett Michaël Demarque Philippe Vernier Kei Yamamoto |
| |
Institution: | 1. Paris‐Saclay Institute of Neuroscience (Neuro‐PSI), CNRS, Université Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette, France;2. TEFOR Core Facility, Paris‐Saclay Institute of Neuroscience (Neuro‐PSI), CNRS, Université Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette, France |
| |
Abstract: | Cerebrospinal fluid‐contacting (CSF‐c) cells containing monoamines such as dopamine (DA) and serotonin (5‐HT) occur in the periventricular zones of the hypothalamic region of most vertebrates except for placental mammals. Here we compare the organization of the CSF‐c cells in chicken, Xenopus, and zebrafish, by analyzing the expression of synthetic enzymes of DA and 5‐HT, respectively, tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH), and draw an evolutionary scenario for this cell population. Due to the lack of TH immunoreactivity in this region, the hypothalamic CSF‐c cells have been thought to take up DA from the ventricle instead of synthesizing it. We demonstrate that a second TH gene (TH2) is expressed in the CSF‐c cells of all the three species, suggesting that these cells do indeed synthetize DA. Furthermore, we found that many CSF‐c cells coexpress TH2 and TPH1 and contain both DA and 5‐HT, a dual neurotransmitter phenotype hitherto undescribed in the brain of any vertebrate. The similarities of CSF‐c cells in chicken, Xenopus, and zebrafish suggest that these characteristics are inherited from the common ancestor of the Osteichthyes. A significant difference between tetrapods and teleosts is that teleosts possess an additional CSF‐c cell population around the posterior recess (PR) that has emerged in specific groups of Actinopterygii. Our comparative analysis reveals that the hypothalamus in mammals and teleosts has evolved in a divergent manner: placental mammals have lost the monoaminergic CSF‐c cells, while teleosts have increased their relative number. |
| |
Keywords: | CSF‐contacting cells dopamine evolution hypothalamus monoamine paraventricular organ serotonin ventricle RRID: AB_2201528 RRID: AB_2314334 RRID: AB_477522 RRID: AB_94865 RRID: AB_221448 RRID: AB_2314655 RRID: AB_10000240 RRID: AB_87181 |
|
|