This chapter will start by reviewing the fundamental features of adult neurogenesis in vertebrates. Noteworthy, the number of proliferation zones in the adult brain is strongly reduced in the transition between fish and tetrapods and even more in mammals compared to non-mammalian vertebrates. Although the functional meaning of this restriction is still uncertain, this issue seems to be linked to different degrees of post-natal brain growth, and to whether constitutive adult proliferation results in a net increase in the number of neurons with age (fish, amphibians and reptiles) or in neuronal turn-over (birds and mammals). While the adult mammalian brain generally contains only two neurogenic areas, the adult teleost brain displays numerous proliferative niches, and this feature is accompanied by a high capacity to positively respond to injury. A considerable amount of information on fish adult neurogenesis has been collected in the teleost zebrafish, due to its importance as a genetic and developmental model organism. In contrast, fewer data are available in goldfish, although it still represents the preferred teleost model for the study of visual function and regeneration. In the second part of this chapter we will therefore present original data obtained in our laboratory illustrating the distribution of proliferation zones in the adult goldfish brain. We will then discuss the possible role of the endocannabinoid system (ECS) in teleost adult neurogenesis. Recent functional studies in mammals have demonstrated that endocannabinoids are lipid mediators involved in the modulation of several steps of both adult and embryonic neurogenesis: proliferation, migration, specification, survival, phenotypic differentiation and control of the establishment of synaptic communication. In particular, several in vivo and in vitro studies support the involvement of the two main cannabinoid receptors (CB1 and CB2) in the modulation of neural progenitor proliferation. In the goldfish, we investigated the presence of the ECS in telencephalic proliferation zones and found that both CB1 and CB2 are expressed by putative radial glial neural progenitors, thus placing endocannabinoids as candidate modulators of teleost adult neurogenic processes.
Adult Neurogenesis in Teleosts: Endocannabinoids as Candidate Modulators in the Goldfish Forebrain
POMATTO, VALENTINA;COTTONE, Erika;FASOLO, Aldo;BOVOLIN, Patrizia
2014-01-01
Abstract
This chapter will start by reviewing the fundamental features of adult neurogenesis in vertebrates. Noteworthy, the number of proliferation zones in the adult brain is strongly reduced in the transition between fish and tetrapods and even more in mammals compared to non-mammalian vertebrates. Although the functional meaning of this restriction is still uncertain, this issue seems to be linked to different degrees of post-natal brain growth, and to whether constitutive adult proliferation results in a net increase in the number of neurons with age (fish, amphibians and reptiles) or in neuronal turn-over (birds and mammals). While the adult mammalian brain generally contains only two neurogenic areas, the adult teleost brain displays numerous proliferative niches, and this feature is accompanied by a high capacity to positively respond to injury. A considerable amount of information on fish adult neurogenesis has been collected in the teleost zebrafish, due to its importance as a genetic and developmental model organism. In contrast, fewer data are available in goldfish, although it still represents the preferred teleost model for the study of visual function and regeneration. In the second part of this chapter we will therefore present original data obtained in our laboratory illustrating the distribution of proliferation zones in the adult goldfish brain. We will then discuss the possible role of the endocannabinoid system (ECS) in teleost adult neurogenesis. Recent functional studies in mammals have demonstrated that endocannabinoids are lipid mediators involved in the modulation of several steps of both adult and embryonic neurogenesis: proliferation, migration, specification, survival, phenotypic differentiation and control of the establishment of synaptic communication. In particular, several in vivo and in vitro studies support the involvement of the two main cannabinoid receptors (CB1 and CB2) in the modulation of neural progenitor proliferation. In the goldfish, we investigated the presence of the ECS in telencephalic proliferation zones and found that both CB1 and CB2 are expressed by putative radial glial neural progenitors, thus placing endocannabinoids as candidate modulators of teleost adult neurogenic processes.
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