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XB-ART-53508
J Comp Neurol June 15, 2017; 525 (9): 2265-2283.

Comparative analysis of monoaminergic cerebrospinal fluid-contacting cells in Osteichthyes (bony vertebrates).

Xavier AL , Fontaine R , Bloch S , Affaticati P , Jenett A , Demarque M , Vernier P , Yamamoto K .


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.

PubMed ID: 28295297
PMC ID: PMC6585609
Article link: J Comp Neurol


Species referenced: Xenopus
Genes referenced: elavl3 slc18a2 th th2 tph1 tph2
Antibodies: Elavl3 Ab1 Th Ab5


Article Images: [+] show captions
References [+] :
Affaticati, Identification of the optic recess region as a morphogenetic entity in the zebrafish forebrain. 2016, Pubmed