Context-dependent fluctuation of serotonin in the auditory midbrain: the influence of sex, reproductive state and experience.
In the face of changing behavioral situations, plasticity of sensory systems can be a valuable mechanism to facilitate appropriate behavioral responses. In the auditory system, the neurotransmitter serotonin is an important messenger for context-dependent regulation because it is sensitive to both external events and internal state, and it modulates neural activity. In male mice, serotonin increases in the auditory midbrain region, the inferior colliculus (IC), in response to changes in behavioral context such as restriction stress and social contact. Female mice have not been measured in similar contexts, although the serotonergic system is sexually dimorphic in many ways. In the present study, we investigated the effects of sex, experience and estrous state on the fluctuation of serotonin in the IC across contexts, as well as potential relationships between behavior and serotonin. Contrary to our expectation, there were no sex differences in increases of serotonin in response to a restriction stimulus. Both sexes had larger increases in second exposures, suggesting experience plays a role in serotonergic release in the IC. In females, serotonin increased during both restriction and interactions with males; however, the increase was more rapid during restriction. There was no effect of female estrous phase on the serotonergic change for either context, but serotonin was related to behavioral activity in females interacting with males. These results show that changes in behavioral context induce increases in serotonin in the IC by a mechanism that appears to be uninfluenced by sex or estrous state, but may depend on experience and behavioral activity.
['Hanson|Jessica L|JL|', 'Hurley|Laura M|LM|']
D000818:Animals D001522:Behavior, Animal D030762:Estrous Cycle D005260:Female D007245:Inferior Colliculi D008297:Male D051379:Mice D008808:Mice, Inbred CBA D012701:Serotonin D012727:Sex Characteristics D012737:Sex Factors D012726:Sexual Behavior, Animal D009435:Synaptic Transmission
Auditory system Inferior colliculus Context Estrous Neuromodulation Sensory processing