TY - JOUR
T1 - Presynaptic dopaminergic neurotransmission mediates amphetamine-induced unconditioned but not amphetamine-conditioned locomotion and defecation in the rat
AU - Di Lullo, Sherry L.
AU - Martin-Iverson, Mathew T.
PY - 1991/12/24
Y1 - 1991/12/24
N2 - A series of experiments were conducted to investigate the role of presynaptic dopamine (DA) and noradrenaline (NA) neurotransmission in stimulant-unconditioned locomotion and defecation. (+)-Amphetamine (AMP, 1.5 mg/kg, s.c.) increased both locomotion and defecation in rats, and both of these effects were conditioned to environmental stimuli. Some groups of rats were treated with DSP4 (50 mg/kg, i.p.), a selective, long-lasting NA neurotoxin, given 7 days prior to conditioning with AMP. This treatment depleted forebrain NA to between 1% and 54% of control levels, depending on the brain region, but did not attenuate either AMP-unconditioned or conditioned locomotion. These results indicate that NA does not mediate either AMP unconditioned or conditioned locomotion. α-Methyl-para-tyrosine methyl ester (αMPT, 25-50 mg/kg, s.c.), a selective inhibitor of catecholamine synthesis given during conditioning with AMP, attenuated unconditioned AMP-induced locomotion and defecation but did not influence AMP-conditioned locomotion and defecation. Thus, αMPT blocked AMP-induced unconditioned locomotion, supporting the hypothesis that the locomotor and defecation stimulant effects of AMP are mediated by DA release. In spite of the attenuation of the direct effects of AMP, αMPT did not attenuate AMP-conditioned locomotion or defecation. It is concluded that AMP-induced release of dopamine is responsible for the unconditioned behavioral effects of amphetamine but not for the conditioning of amphetamine-induced locomotion and defecation.
AB - A series of experiments were conducted to investigate the role of presynaptic dopamine (DA) and noradrenaline (NA) neurotransmission in stimulant-unconditioned locomotion and defecation. (+)-Amphetamine (AMP, 1.5 mg/kg, s.c.) increased both locomotion and defecation in rats, and both of these effects were conditioned to environmental stimuli. Some groups of rats were treated with DSP4 (50 mg/kg, i.p.), a selective, long-lasting NA neurotoxin, given 7 days prior to conditioning with AMP. This treatment depleted forebrain NA to between 1% and 54% of control levels, depending on the brain region, but did not attenuate either AMP-unconditioned or conditioned locomotion. These results indicate that NA does not mediate either AMP unconditioned or conditioned locomotion. α-Methyl-para-tyrosine methyl ester (αMPT, 25-50 mg/kg, s.c.), a selective inhibitor of catecholamine synthesis given during conditioning with AMP, attenuated unconditioned AMP-induced locomotion and defecation but did not influence AMP-conditioned locomotion and defecation. Thus, αMPT blocked AMP-induced unconditioned locomotion, supporting the hypothesis that the locomotor and defecation stimulant effects of AMP are mediated by DA release. In spite of the attenuation of the direct effects of AMP, αMPT did not attenuate AMP-conditioned locomotion or defecation. It is concluded that AMP-induced release of dopamine is responsible for the unconditioned behavioral effects of amphetamine but not for the conditioning of amphetamine-induced locomotion and defecation.
KW - Amphetamine
KW - Conditioned defecation
KW - Conditioned locomotion
KW - Dopamine
KW - DSP4
KW - Noradrenaline
KW - Rat
KW - α-Methyl-para-tyrosine
UR - http://www.scopus.com/inward/record.url?scp=0026355785&partnerID=8YFLogxK
U2 - 10.1016/0006-8993(91)91377-D
DO - 10.1016/0006-8993(91)91377-D
M3 - Article
C2 - 1726071
AN - SCOPUS:0026355785
VL - 568
SP - 45
EP - 54
JO - Brain Research
JF - Brain Research
SN - 0006-8993
IS - 1-2
ER -