Neuronal Release of Serotonin in the Cerebellum of Behaving Rats: An In Vivo Microdialysis Study

Abstract

ou,,sil of Nes,oc/,emjvtrv I ippiucotI-Riven Publishers. Philadelphia I 906 lnterriaiioiisl Society or NeurochemistryAbstract: Release of endogenous serotonin [5-hydroxytryptamirie (5-HT)] in the cerebellum of awake rats was characterized using in vivo microdialysis. 5-HT output was increased (-70%) by local application of KCI (100 mM) and was reduced (--60%) by both tetrodotoxin (0.5 pM) and omission of Ca 2 from the perfusion fluid. 5-HT release was decreased (-70%) by the selective 5-HT 1A agonist 8-hydroxy-2-(di-n -propylamino)tetralin (0.25 mg/kg, s.c.), and this effect was rapidly reversed by a selective 5-HT1A antagonist, N-carboxamide trihydrochloride (WAY-i 00635; 0.1 mg /kg, i.p.). These results indicate that a large portion of the measurable 5-HT output in the cerebellum is of neuronal origin, is dependent on impulse flow, and is sensitive to 5-HT1A autoreceptor activation. Further studies examined the relationship between 5-HT levels and general activity of the animals across the light-dark transition and during behavioral manipulations. Both 5-HT levels and behavioral activity were significantly elevated during the dark period, with changes in 5-HT efflux closely paralleling changes in activity. Similar increases (~-40%)in 5-HT output were observed during both feeding and feeding in the presence of a stressor (tail pinch). These findings suggest that behavioral state is an important factor determining neuronal 5-HT release in cerebellum under 6/7

The 5-HT7 receptor triggers cerebellar long-term synaptic depression via PKC-MAPK

“…In such a way, 5-HT can potentially decrease the inhibitory drive of PCs to deep cerebellar nuclei neurons and ultimately refine the motor output. This hypothesis is in line with previous findings showing a correlation between 5-HT level in the cerebellar cortex and motor activity (Mendlin et al, 1996).…”

“…The role of 5-HT in the cerebellum has been assumed as a regulator of sensorimotor learning. First, 5-HT release into the cerebellum is positively correlated with the level and type of motor activity (Mendlin et al, 1996). Second, chronic treatment with 5-HTP or buspirone, a 5-HT1A receptor (5-HT1AR) partial agonist, improves the motor coordination deficits in Lurcher mouse, a model of cerebellar neurodegeneration (Le Marec et al, 2001).…”

Neural Connections of the Anterior Hypothalamus and Agonistic Behavior in Golden Hamsters

“…* p < 0.05, Student t-test, two-tailed as compared to the controls. bility is supported by results from previous studies performed in rats [Matsuo et al, 1996;Mendlin et al, 1996;Rueter and Jacobs, 1996]. Furthermore, it remains to be determined whether the experimental conditions in our study enhanced the release of 5-HT within the AH.…”

Intracellular calcium dynamics permit a Purkinje neuron model to perform toggle and gain computations upon its inputs

“…In addition, SK has been shown to be under transmitter control in many types of neurons (Nicoll, 1988). Interestingly, in vivo , electrical stimulation of the Raphe complex releases serotonin and induces long pauses in Purkinje cell output (Strahlendorf et al, 1979; Weiss and Pellet, 1982), consistent with the ability for serotonin to increase toggling behavior and affect locomotor activity (Mendlin et al, 1996). …”