The local application of MK-801 (300 m; = 7) by reverse dialysis prevented the increase in 5-HT launch induced by the second stimulation conditions

The local application of MK-801 (300 m; = 7) by reverse dialysis prevented the increase in 5-HT launch induced by the second stimulation conditions. from 2.0 mm outer diameter (o.d.) capillary glass (WPI, Saratosa, FL) drawn on a Narishige (Tokyo, Japan) PE-2 pipette puller and filled with 2 mNaCl. The electrode 7-Methoxyisoflavone impedance was lowered to 4C10 M by moving 500 msec 150 V DC pulses (Grass activation model S-48) through the electrode. Constant current electrical stimuli were generated having a Grass stimulation unit S-48 connected to a Grass SIU 5 stimulus isolation unit. mPFC neurons were stimulated 7-Methoxyisoflavone with monophasic square wave pulses (0.2 msec, 0.9 Hz, 0.5C2.5 mA). Single-unit extracellular recordings were amplified having a Neurodata IR283 (Cygnus Technology, Delaware Water Space, PA), postamplified, and filtered having a Cibertec (Madrid, Spain) amplifier, and computed on-line using a DAT 1401plus interface system Spike2 software (Cambridge Electronic Design, Cambridge, UK). Data were also recorded on magnetic audiotape for off-line recording if necessary. Descents were performed along the midline. 5-HT neurons were usually experienced 4.8C6.5 mm below the brain surface and identified relating to previously explained electrophysiological criteria (Wang and Aghajanian, 1977). Serotonergic neurons 7-Methoxyisoflavone exhibited a regular firing rate with frequencies of 0.4C3.5 Hz, and 2C5 msec biphasic or triphasic extracellular waveforms and were inhibited from the 5-HT1A agonist 8-OH-DPAT. Surgery and microdialysis?procedures Microdialysis methods in unanesthetized rats were performed essentially while described in Adell and Artigas (1991). Anesthetized rats (pentobarbitone, 60 mg/kg, i.p.) were placed in a stereotaxic apparatus and implanted with microdialysis probes. Dual probe microdialysis was performed by implanting two I-shaped probes in the mPFC (AP +3.4, L ?0.8, DV ?6.0) and the DR (AP ?7.8, L ?3.1, DV ?7.5). Probes in the DR were implanted with an angle of 30 to avoid obstruction of the cerebral aqueduct. The space of membrane exposed to the brain cells was 4 mm long (o.d. 0.25 mm) in mPFC and 1.5 mm long in DR. One group of rats was implanted with 4 mm probes in the lateral prefrontal cortex (AP +3.4, L ?3.0, DV ?6.0) and DR (while above) to control for the effects in DR of the local software of 8-OH-DPAT in mPFC. Animals were allowed to recover from surgery treatment for 20 hr, and then probes were perfused with artificial CSF (aCSF) (in mm: 125NaCl, 2.5 KCl, 1.26 CaCl2, and 1.18 MgCl2) containing 1 m citalopram at 0.25 l/min. Sample collection started 60 min after the beginning of perfusion. Dialysate samples were collected every 20 min (5 l). Usually five or six fractions were collected before drug administration, of which four were used to obtain the individual basal ideals. Two different microdialysis experiments were carried out in unanesthetized rats. In the 1st one, groups of rats were given with two sequential injections of 8-OH-DPAT (0.1 + 0.1 mg/kg, s.c.) 3 hr apart. Animals of the control group received the two injections in identical conditions, 7-Methoxyisoflavone and the effects of 8-OH-DPAT on 5-HT launch were examined in the DR and mPFC (rats experienced dual implants). Two Rabbit polyclonal to AK3L1 additional groups of rats received the 1st 8-OH-DPAT injection in control conditions, and the second one was given while the 5-HT1A receptor antagonist WAY-100635 (100 m) was perfused into the DR or the mPFC (perfusions began 40 min before the second 8-OH-DPAT injection) to examine the part of presynaptic and postsynaptic 5-HT1A receptors in the control of 5-HT launch in both areas. The ratios between the inhibitions of the second and 1st injection on 5-HT launch were calculated and compared in both organizations (i.e., with and without WAY-100635 in the DR or mPFC). In another experiment, 8-OH-DPAT (100 and 300 m; 120 min each) was perfused through the probe in mPFC, and 5-HT was analyzed in dialysates from your mPFC and DR of the same animals (dual implants). The total amount of 8-OH-DPAT perfused through the dialysis probes at the two concentrations used was 3 and 9 nmol over the course of 2 hr (uncorrected for probe recovery). Two groups of settings were used, one receiving aCSF in both sites for the entire collection period (sham changes of perfusion syringes were also performed with this group) and another one in which the prefrontal probes were placed more laterally, in an area devoid of neurons projecting to the DR (Peyron et al., 1998; observe.

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