TY - JOUR

T1 - Comparative analysis of monoaminergic cerebrospinal fluid-contacting cells in Osteichthyes (bony vertebrates)

AU - Xavier, Anna L.

AU - Fontaine, Romain

AU - Bloch, Solal

AU - Affaticati, Pierre

AU - Jenett, Arnim

AU - Demarque, Michaël

AU - Vernier, Philippe

AU - Yamamoto, Kei

PY - 2017/6

Y1 - 2017/6

N2 - 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.

AB - 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.

KW - CSF-contacting cells

KW - dopamine

KW - evolution

KW - hypothalamus

KW - monoamine

KW - paraventricular organ

KW - RRID: AB_10000240

KW - RRID: AB_2201528

KW - RRID: AB_221448

KW - RRID: AB_2314334

KW - RRID: AB_2314655

KW - RRID: AB_477522

KW - RRID: AB_87181

KW - RRID: AB_94865

KW - serotonin

KW - ventricle

U2 - 10.1002/cne.24204

DO - 10.1002/cne.24204

M3 - Journal article

C2 - 28295297

AN - SCOPUS:85016783167

VL - 525

SP - 2265

EP - 2283

JO - The Journal of Comparative Neurology

JF - The Journal of Comparative Neurology

SN - 0021-9967

IS - 9

ER -