TY - JOUR
T1 - Morphine increases the activity of midbrain dopamine neurons in vitro
AU - Trulson, Michael E.
AU - Arasteh, Kamyar
PY - 1985/8/7
Y1 - 1985/8/7
N2 - Morphine produced a dose-dependent increase in the activity of dopamine-containing neurons in the substantia nigra and ventral tegmental area recorded from mouse brain slices in vitro. The response was not changed in a low calcium/high magnesium incubation medium, indicating that the observed effects are the result of the direct action of morphine on dopamine neurons. Furthermore, a specific opiate antagonist, naloxone, versed the excitatory effects of morphine in both brain regions, while naloxone alone had no significant effect on the activity of dopaminergic neurons. Morphine was more potent on ventral tegmental area than substantia nigra dopamine neurons. β-Endorphin excited ventral tegmental area neurons but not substantia nigra cells, while [Leu5]enkephalin activated cells in both nuclei. These latter responses were blocked by naloxone. These data suggest that midbrain dopamine neurons contain receptors for opiates, and that ventral tegmental area neurons are more sensitive to the action of opiates than substantia nigra neurons.
AB - Morphine produced a dose-dependent increase in the activity of dopamine-containing neurons in the substantia nigra and ventral tegmental area recorded from mouse brain slices in vitro. The response was not changed in a low calcium/high magnesium incubation medium, indicating that the observed effects are the result of the direct action of morphine on dopamine neurons. Furthermore, a specific opiate antagonist, naloxone, versed the excitatory effects of morphine in both brain regions, while naloxone alone had no significant effect on the activity of dopaminergic neurons. Morphine was more potent on ventral tegmental area than substantia nigra dopamine neurons. β-Endorphin excited ventral tegmental area neurons but not substantia nigra cells, while [Leu5]enkephalin activated cells in both nuclei. These latter responses were blocked by naloxone. These data suggest that midbrain dopamine neurons contain receptors for opiates, and that ventral tegmental area neurons are more sensitive to the action of opiates than substantia nigra neurons.
KW - Dopamine
KW - In vitro
KW - Morphine
KW - Single units
KW - Substantia nigra
KW - Ventral tegmental area
UR - http://www.scopus.com/inward/record.url?scp=0022181689&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0022181689&partnerID=8YFLogxK
U2 - 10.1016/0014-2999(85)90530-8
DO - 10.1016/0014-2999(85)90530-8
M3 - Article
C2 - 2931290
AN - SCOPUS:0022181689
SN - 0014-2999
VL - 114
SP - 105
EP - 109
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 1
ER -