Examining the Effects of Serotonin on Medium Spiny Neurons (MSNs)

Abstract

Serotonin is known to be the key hormone in stabilizing our mood and feelings of well-being. The relation of alterations in the levels of serotonin in the central nervous system and depression has been well-established. The most common antidepressants prescribed to alleviate the symptoms of depression are selective serotonin reuptake inhibitors (SSRIs). These are known to target serotonin and increase its levels in the brain. Due to this property, the consumption of antidepressants by pregnant women has been subject to scrutiny, as the effects of these drugs on the developing embryo have not been studied extensively. These include the effects of serotonin on the development of medium spiny neurons (MSNs), the major type of neuron that constitute the striatum that are known to have distinct morphological traits of cell body size, dendritic arborization pattern and high density of dendritic spines. Although many studies have focused on the role of serotonin in regulating function of the mature striatum, no studies (that we can find) have specifically examined the role of serotonin on MSN development. Based on its role in regulating striatal activity and effects on dendritic growth in other types of neurons, we hypothesize that serotonin will also regulate MSN dendritic arborization. However, mature MSNs express at least 7 different types of serotonin receptors. The effect of serotonin on MSN development will likely depend on which receptors are most highly expressed or active during development. It is therefore impossible to predict whether serotonin will enhance or reduce MSN dendritic arborization.