Environmental enrichment influences neuronal stem cells in the adult crayfish brain

Abstract

New neurons are incorporated throughout life into the brains of many vertebrate and non-vertebrate species. This process of adult neurogenesis is regulated by a variety of external and endogenous factors, including environmental enrichment, which increases the production of neurons in juvenile mice and crayfish. The primary goal of the present study was to exploit the spatial separation of the neuronal precursor cell lineage in crayfish to determine which generation(s) of precursors is altered by environmental conditions. Further, in crayfish, an intimate relationship between the 1st generation neuronal precursors (stem cells) and cells circulating in the hemolymph has been proposed (Zhang et al., 2009). Therefore, a second goal was to assess whether environmental enrichment alters the numbers or types of cells circulating in the hemolymph. We find that neurogenesis in the brains of sexually differentiated procambarid crayfish is enhanced by environmental enrichment as previously demonstrated by Sandeman and Sandeman (2000) in young, sexually undifferentiated Cherax destructor. We also show that environmental enrichment increases the cell cycle rate of neuronal stem cells. While there was no effect of environment on the overall numbers of cells circulating in the hemolymph, enrichment resulted in increased expression of glutamine synthetase, a marker of the neuronal stem cells, in a small percentage of circulating cells; there was little or no expression of this enzyme in hemolymph cells extracted from deprived animals. Thus, environmental enrichment influences the rate of neuronal stem cell division in adult crayfish, as well as the composition of cells circulating in the hemolymph.

Adult neurogenesis in the central olfactory pathway of dendrobranchiate and caridean shrimps: New insights into the evolution of the deutocerebral proliferative system in reptant decapods

“…However, adult neurogenesis in crustaceans is known to be influenced by a number of different factors including environmental conditions, diurnal effects or serotonin levels (reviewed in . Accordingly, for a closer view on proliferative activity and structural complexity of the olfactory system in reptant decapods, we have considered only those studies in which BrdU exposure times included 24 h. Nevertheless, our compilation of data does comprise obvious errors because, for example, we could not assess the ages of the investigated specimens from many of these studies, a factor which also influences the proliferation rate (Schmidt and Harzsch, 1999;Sandeman and Sandeman, 2000;Ayub et al, 2010). What is more, some values had to be estimated from bar graphs (Sandeman and Sandeman, 2000) and were coarsely rounded.…”

Plasticity and Adult Neurogenesis in Amphibians and Reptiles: More Questions than Answers

“…Enriched environments have been shown to increase the number of new cells in the brains of mammals, of course, both in the hippocampus [Kempermann et al, 1997; for a review, see Kempermann et al, 2010] and, if the olfactory environment was enhanced, in the olfactory bulb [Rochefort et al, 2002;Rochefort and Liedo, 2005]. They have also been shown to increase neurons in the brains of crustaceans [Ayub et al, 2010], insects [Scotto-Lomassese et al, 2000], and fish [Dunlap, 2016]. A recent study also showed enhancement in pigeons given an enriched environment [Melleu et al, 2016], but only in the hippocampus; other areas of the telencephalon showed no effect or even a decrease in cells.…”

Enriched Environment Increases PCNA and PARP1 Levels in Octopus vulgaris Central Nervous System: First Evidence of Adult Neurogenesis in Lophotrochozoa

“…Also in insects and crustaceans adult, neurogenesis can be affected by environmental stimulation (Hansen and Schmidt, 2001;Scotto-Lomassese et al, 2002;Ben Rokia-Mille et al, 2008;Ghosal et al, 2009;Ayub et al, 2011). In crickets, adult neurogenesis is regulated by sensory inputs, responsible for cell cycle acceleration, and by hormonal levels, affecting the recruitment of progenitors cells (Cayre et al, 2005a(Cayre et al, , 2005b.…”

“…The enriched sensory and social conditions, characterized by the simulation of the wild life, enhance the number of mushroom bodies neuroblasts in housed crickets (Scotto-Lomassese et al, 2000), while the ablation of them implies a damage of learning capabilities (Scotto-Lomassese et al, 2003). Also among the crayfishes, the proliferative potential of the neuronal stem cells can be increased enhancing the quality of the environment of housed animals (Sandeman and Sandeman, 2000;Ayub et al, 2011). Sandeman and Sandeman (2000) showed that animals kept with their sibling in large tanks have a higher number of neurons with respect to animals housed alone in small tanks, furthermore cell body size and their survival result increased.…”