Table 1.
Effects of various olfactory toxicants and injury paradigms on the olfactory epithelium (OE), olfactory bulb (OB), and on olfactory-mediated behaviors of zebrafish, as well as their recovery.
| Toxicant or Injury Paradigm | Effects on OE | Effects on OB | Behavioral Effects | Recovery | Ref. |
|---|---|---|---|---|---|
| Cadmium (Cd) | OSN loss, reduced neurogenesis, ROS increase | Long-term decrease in alarm and avoidance responses | [88,114,115,116,117,118,119] | ||
| Copper (Cu) | Predominantly ciliated OSN loss, decreased OR and ionic channels transcripts | Impaired response to bile salts, reduced alarm response | OSN recovery after 72 h. Partial recovery of bile salt response. | [120,121,122,123,124] | |
| Cobalt (Co) | Acute damage to OE, apoptosis and increased ROS | Alterations in schooling behavior | [125,126] | ||
| Nickel (Ni) | OSN loss and OO anatomical disturbances | [127] | |||
| Uranium (U) | Ciliated OSNs and non-sensory cells damage and loss | Morphological damage and disruption of glomerular structure | [128,129,130] | ||
| Zinc (Zn) | Damage to the sensory epithelium with ciliated OSN loss | Impaired response predominantly to bile salts, and aminoacids. Anxiety-like behaviors and reduction in locomotion | [19,88,133] | ||
| Silver (Ag) | Oxidative stress and expression of oxidative damage genes | [134] | |||
| Chlorpyrifos | Decrease in transcripts related to olfactory sensing and neuronal repair and regeneration | [135] | |||
| Rotenone | Impaired response to amino acids | [136] | |||
| Triton X-100 | Thinning of OE, fused lamellae, inflammation and OSN loss | Deafferentation, glomerular defasciculation, reduction of size and activity. Mitral cell structural alterations | Reduced response to predominantly bile salts, and aminoacids | Following acute exposure, OE regenerates in 5 days; bulbar reinnervation observed in 7 days; functional olfactory recovery at 10 days. Following chronic exposure, OE and OB structure, activity and volume are recovered at 21 days. | [18,20,21,22,32,42,137] |
| Urea | Thinning of OE with crypt OSN loss, upregulation of Gαolf transcript | [138,139] | |||
| Chronic physical olfactory organ lesion | OE damage, inflammation and OSN loss | Bulbar deafferentation and glomerular defasciculation | OE regeneration and OB recovery observed in 7 days. Complete bulbar reinnervation at 21 days | [140] | |
| Olfactory organ removal | Reduction in size and activity. Complete deafferentation, degeneration of both olfactory nerve and glomerular layer. Increased apopotsis | [32,41,42,137,141,142] |