Simultaneous recording of dorsal raphe unit activity and serotonin release in the striatum using voltammetry in awake, behaving cats.

Simultaneous recordings of unit activity in the dorsal raphe nucleus (RD) and serotonin (5HT) release in the striatum were made in the cat. Unit recordings were made using Formvar-coated 32 microns diameter nichrome wires. 5HT release was measured using linear sweep voltammetry with semi-differentiation using electrodes prepared from Teflon-coated 32-gauge stainless steel wire filled with carbon paste and Ag/AgCl electrodes and 27-gauge stainless steel needles as reference and auxiliary electrodes, respectively. The working electrodes were scanned at a rate of 10 mV/s over the range of -0.1 to +0.5 V every 5 minutes using a BAS CV37 voltammograph. During REM sleep RD unit activity was decreased 94% from quiet waking (QW) baseline, while the voltammetric response was decreased by only 57%. Chloral hydrate anesthesia decreased RD unit activity by 18% from QW while the voltammetric response was decreased by 39%. LSD decreased RD unit activity by 50% from QW, but the voltammetric response was decreased by 88%. P-chlorophenylalanine produced no significant change in RD unit activity but decreased the voltammetric response by 82%. These data suggest that RD unit activity and 5HT release often differed dramatically.