Sex differences in adult cell proliferation within the zebrafish (Danio rerio) cerebellum

Abstract

It has been reported that neurons generated in the adult brain show sex-specific differences in several brain regions of lower vertebrates and mammals. The present study questioned whether cell proliferation and survival in the adult zebrafish (Danio rerio) cerebellum, the most mitotically active area of adult teleost brain, is sexually differentiated. Adult zebrafish were treated with the thymidine analogue 5'-bromo-2'-deoxyuridine (BrdU) and allowed to survive for 24 h (short-term) and for 21 days (long-term). BrdU immunohistochemistry allowed visualization of cells incorporating BrdU at the S phase of mitosis. At short-term survival, male zebrafish had a higher number of labelled cells at proliferation sites of the molecular layer of corpus cerebelli (CCe) and the granular layer of the caudal lobe of the cerebellum (LCa) than did females. In long-term survival, BrdU-positive cells were found at their final destination, but only the granular layer of the medial division of the valvula cerebelli showed sex-specific differences in the number of labelled cells. This higher mitotic activity in male cerebellum might be related to sex-specific motor behaviour observed in male zebrafish. To investigate the role of programmed cell death, the terminal deoxynucleotidyl-mediated dUTP nick-end-labelling (TUNEL) method was applied. The vast majority of apoptotic figures occurred in the granular cell layer of valvula and CCe, only in a few cases within the BrdU-retaining cells. Apoptosis was found specifically at the sites of the final destination of proliferating cells, indicating that the close relation of cell birth and death might represent a possible plasticity mechanism in the adult zebrafish cerebellum.

Adult neurogenesis and brain regeneration in zebrafish

“…However, Fgf signaling is required for the maintenance and proliferation of the adult cerebellar progenitors (see below, Kaslin et al, 2009). In addition, sex differences in proliferation have been detected in the adult cerebellum (Ampatzis et al, 2007).…”

Neuronal and glial localization of α2A‐adrenoceptors in the adult zebrafish (Danio rerio) brain

“…Anti-BrdU identifies BrdU (but not thymidine) in single-stranded DNA. The monoclonal antibody against BrdU and has been used previously in zebrafish (Zupanc et al, 2005; Ampatzis and Dermon, 2007) and other teleost species (Zikopoulos et al, 2000) brain, with similar distribution patterns of adult proliferation zones.…”

“…zones (Zupanc et al, 2005;Ampatzis and Dermon, 2007). For this, we performed double-labeling experiments with the S-phase cell marker BrdU, but very few newborn cells were labeled for ␣ 2A -AR, mainly in the optic tectum (TeO), and will not be treated here further.…”

Neurogenesis in the Adult Goldfish Cerebellum

“…Although the putative relationship between learning, memory and adult neurogenesis is intriguing, few studies have addressed this topic in the central nervous system, with the notable exception of the retina (Boucher and Hitchcock, 1998). The goldfish cerebellum was evaluated here as an accessible model system for studies of vertebrate adult neurogenesis, because this part of the brain is central to motor learning and memory, and arguably the site of most widespread neurogenesis in teleosts (Ampatzis and Dermon, 2007). To that end, BrdU, proliferating cell nuclear antigen (PCNA), and beta-III-tubulin immunohistochemistry were combined to compare the cerebellar neuronal proliferation pattern of the goldfish with that of previously scrutinized species like zebrafish and the brown ghost knifefish.…”

“…A large amount of information has been gathered principally through studies in zebrafish (Byrd and Brunjes, 2001;Zupanc et al, 2005;Grandel et al, 2006;Ampatzis and Dermon, 2007;), due to its importance as developmental model organism, and in gymnotiformes such as the brown ghost knifefish (Zupanc and Horschke, 1995;Zupanc, 1999), owing to the wealth of information on brain morphology and function available for this electrocommunicating species. However, for most physiological and behavioral studies related to adult neurogenesis, neither species is ideal, because the zebrafish brain and especially its neurons are too small for many types of experiment, and most researchers do not have easy access to gymnotiformes.…”