神经损伤与修复

    Trace amine-associated receptors at the cross-road between innate olfaction of amines, emotions, and adult neurogenesis
  • Figure 1|TAAR5 receptors are expressed in limbic brain areas involved in the transduction of olfactory information and neurogenic zones. 

    The use of TAAR5 knockout (TAAR5-KO) mice allowed us to explore the expression pattern of TAAR5 in the brain and elucidate its neuronal functions. In TAAR5-KO mice, the TAAR5 gene was replaced with a cassette, containing LacZ insertion (Espinoza et al., 2020). By analyzing the expression of LacZ, we observed that in the olfactory bulb TAAR5 can be found not only in the glomerular layer but also in mitral and other cells projecting to the limbic brain areas. Furthermore, TAAR5 was observed in the regions of the limbic system, such as the amygdala, the hippocampus, the entorhinal cortex, the nucleus accumbens, the piriform cortex, the thalamic, and hypothalamic nuclei - the regions receiving olfactory input and known to regulate emotional behaviors (Figure 1). The localization of TAAR5 in these limbic areas, together with its presence in the olfactory system, suggests that TAAR5 is involved in the transduction of innate olfactory input into the limbic emotional system. Behavioral studies in TAAR5-KO mice showed that TAAR5 can be involved in the regulation of emotional behaviors. TAAR5-KO mice had significantly decreased anxiety levels in several tests. They also demonstrated increased exploratory behavior in the open field test, with no significant changes in general locomotor activity. Together with decreased anxiety, TAAR5-KO mice also showed decreased depression-like behavior in the learned helplessness test. Taken together, these data indicate that the lack of TAAR5 receptors resulted in a change in several aspects of the emotional behavior of mice (Espinoza et al., 2020). The presence of TAAR5 receptors both in the olfactory and the limbic systems, together with involvement in emotional behavior seems intriguing and yet very logical. Olfactory input is important in the function of the brain limbic system. It is known that removal of olfactory bulbs (olfactory bulbectomy) causes changes in the function of limbic brain areas as well as alterations in behaviors, similar to those that are observed in depressed patients (Morales-Medina et al., 2017). 

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  • 发布日期: 2021-12-17  浏览: 492
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