Peripheral sensory deafferentation affects olfactory bulb neurogenesis in zebrafish

Abstract

The potential effects of removal of olfactory input on adult neurogenesis in the olfactory bulb were examined. Olfactory organs of adult zebrafish were permanently and completely ablated by cautery and animals were exposed to bromodeoxyuridine then examined following short (4 hour) or long (3 week) survival periods. Short survival times allowed analysis of cell proliferation in the olfactory bulb. Long survival times permitted investigation of survival of adult-formed cells. Deafferentation did not immediately affect the dividing cells in the bulb but did affect the number of adult-formed cells, some of which expressed a neuronal marker, present in the bulb three weeks later. Thus, afferent removal influenced the fate of newly formed cells by impacting subsequent divisions, maturation, or survival of those cells. One week of deafferentation altered the pattern of cell genesis, with a significant increase in the number of dividing cells located in the olfactory bulb and also in the ventral telencephalic proliferation zone. Sham surgery did not impact either proliferation or survival of adultformed cells in the olfactory bulb, suggesting that the deafferentation effect is specific. Thus, afferent innervation is necessary for normal cell proliferation and maintenance of the olfactory bulb in adult zebrafish.

Is there a relationship between adult neurogenesis and neuron generation following injury across evolution?

“…, 1978). A similar outcome has been reported in zebrafish following cauterization of the olfactory neuroepithelium, supporting the notion that adult newborn neurons, like embryonic ones, require functional input for survival (Petreanu & Alvarez‐Buylla, 2002; Villanueva & Byrd‐Jacobs, 2009).…”

Sensory‐specific modulation of adult neurogenesis in sensory structures is associated with the type of stem cell present in the neurogenic niche of the zebrafish brain

“…PGZ). Earlier olfactory sensory deprivation studies in zebrafish (Villanueva & Byrd‐Jacobs, ), along with assays used here exposing animals to a sensory‐enriched environment, reveal a main effect at the level of neuronal survival in the bulb. Conversely, studies employing goldfish and zebrafish models have shown that removal of retinal fiber input or reductions in the available visual stimuli within the environment primarily lead to changes in the size of the stem/progenitor population in the PGZ of the TeO (Raymond et al ., ; Lindsey & Tropepe, ).…”

“…Studies in adult zebrafish have shown that the reverse experiment (i.e. removal of ambient olfactory stimuli) most directly effects the proportion of surviving neurons in the OB following ablation of afferent innervation from the olfactory organs, rather than changes in the proliferative pool (Villanueva & Byrd‐Jacobs, ).…”

The Olfactory System as a Puzzle: Playing With Its Pieces

“…In addition, similar to olfactory deprivation, ORN loss causes a concomitant reduction in adult OB neurogenesis due to an increase in apoptosis (Villanueva and Byrd‐Jacobs, ). In fact, a recent investigation has shown that the increase in apoptosis within the OB is related to the inflammation process and microglial activation that follow olfactory deinnervation (Lazarini et al, ).…”