XXXX -induced @entity4053 decreases single-unit activity of serotonergic medullary raphe neurons in freely moving @entity468 : relationship to sympathetic and motor output.

@entity2661 @entity4053 @entity2922 @entity15165 @entity468 @entity413
Serotonergic single-unit activity during glucoregulatory challenges was studied in the nuclei raphe obscurus (NRO) and raphe pallidus (NRP) of freely moving @entity468 . Systemic @entity15165 administration (2-4 IU/kg, i.v.) suppressed neuronal activity by approximately 40% in direct relationship to blood @entity413 levels and in inverse relationship to plasma @entity2922 levels. NRO and NRP serotonergic neurons displayed a temporary recovery in unit activity in response to i.v. @entity413 administration (500 mg/kg), which temporarily reversed @entity15165 -induced @entity4053 . The neuronal responses to @entity15165 and subsequent @entity413 administration were also directly related to changes in integrated nuchal electromyographic activity. Serotonergic unit activity remained unchanged after @entity413 loading (500 mg/kg, i.v.), which produced a four-fold increase in blood @entity413 . Thus, medullary serotonergic neurons appear to be sensitive to reductions, but not increases, in blood @entity413 . The observed inverse relationship between unit activity and plasma @entity2661 does not support a postulated sympathoexcitatory role for these neurons. Instead, the parallel changes in single-unit activity and integrated muscle activity support the hypothesis that the activity of medullary serotonergic neurons is linked to motor output. These neurons may modulate autonomic outflow, but only in relationship to their primary role in motor control. Finally, medullary serotonergic neurons may play a protective role in maintaining @entity413 homeostasis by disfacilitating the output of the somatomotor system, and hence diminishing muscle energy demands, when peripheral @entity413 availability is low.
