Review article The choroid plexus as a sex hormone target: Functional implications Cecília R.A. Santos a,⇑ , Ana Catarina Duarte a , Telma Quintela a , Joana Tomás a , Tânia Albuquerque a , Fernanda Marques b,c , Joana Almeida Palha b,c , Isabel Gonçalves a a CICS-UBI – Health Sciences Research Centre, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal b Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal c ICVS/3B’s – PT Government Associate Laboratory, Braga/Guimarães, Portugal article info Article history: Received 14 September 2016 Received in revised form 25 November 2016 Accepted 12 December 2016 Available online 18 December 2016 Keywords: Choroid plexus Brain barriers Immune surveillance Chemical surveillance Sex hormones Circadian rhythm Olfactory signalling Taste signalling Neurogenesis Cerebrospinal fluid abstract The choroid plexuses (CPs) are highly vascularized branched structures that protrude into the ventricles of the brain, and form a unique interface between the blood and the cerebrospinal fluid (CSF). In recent years, novel functions have been attributed to this tissue such as in immune and chemical surveillance of the central nervous system, brain development, adult neurogenesis and circadian rhythm regulation. Sex hormones (SH) are widely recognized as modulators in several neurodegenerative diseases, and there is evidence that estrogens and androgens regulate several fundamental biological functions in the CPs. Therefore, SH are likely to affect the composition of the CSF impacting on brain homeostasis. This review will look at implications of the CPs’ sex-related specificities. Ó 2016 Elsevier Inc. All rights reserved. Contents 1. Introduction ......................................................................................................... 104 2. Search strategy, publication selection criteria and data analysis ............................................................... 104 3. The choroid plexus as a sex hormone target ............................................................................... 105 3.1. Progesterone receptors in the CPs .................................................................................. 105 3.2. Estrogen receptors in the CPs ...................................................................................... 105 3.3. Androgen receptors in the CPs ..................................................................................... 105 3.4. Effects of gonadectomy and sex-related differences in the CPs’ transcriptome .............................................. 106 4. Functional implications of sex hormone regulation in the CPs ................................................................. 108 4.1. Production and composition of CSF ................................................................................. 108 4.2. The blood-CSF barrier ............................................................................................ 109 4.3. Immune surveillance ............................................................................................. 111 4.4. Chemical surveillance ............................................................................................ 111 4.4.1. Taste signalling .......................................................................................... 111 4.4.2. Olfactory signalling....................................................................................... 112 4.4.3. Clearance of xenobiotics................................................................................... 113 4.4.4. Clearance of amyloid beta ................................................................................. 113 4.5. Neurogenesis ................................................................................................... 114 4.6. The CPs as a circadian oscillator.................................................................................... 116 http://dx.doi.org/10.1016/j.yfrne.2016.12.002 0091-3022/Ó 2016 Elsevier Inc. All rights reserved. ⇑ Corresponding author at: Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal. E-mail address: csantos@fcsaude.ubi.pt (C.R.A. Santos). Frontiers in Neuroendocrinology 44 (2017) 103–121 Contents lists available at ScienceDirect Frontiers in Neuroendocrinology journal homepage: www.elsevier.com/locate/yfrne