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Effects of crus cerebri lesions and repeated amphetamine treatment on the activity of nigral dopaminergic neurons
Author(s) -
Heidenreich Byron A.,
Rebec George V.
Publication year - 2000
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/1098-2396(200010)38:1<80::aid-syn9>3.0.co;2-1
Subject(s) - pars compacta , bursting , substantia nigra , amphetamine , dopaminergic , neuroscience , dopamine , ventral tegmental area , chemistry , postsynaptic potential , neuron , anesthesia , medicine , psychology , receptor
Previous research suggests that the firing rate of dopamine (DA) neurons in the substantia nigra pars compacta (SNC) may be altered by repeated DA agonist treatment. Because changes in the frequency of DA activity could reflect the firing patterns (e.g., bursting) of the neurons sampled, this study examined both the firing rate and pattern of SNC DA neurons after long‐term amphetamine (AMPH) treatment (5 mg/kg d ‐AMPH s.c. twice daily for 6 days). To assess the contribution of postsynaptic feedback from the forebrain, unilateral electrolytic lesions were made to the crus cerebri (CC), containing the striatonigral pathway, prior to AMPH treatment. Single‐unit activity of presumed SNC DA neurons was recorded in adult male rats under urethane anesthesia. Spontaneous firing rate was reduced by AMPH treatment, relative to saline vehicle, but was unaffected by CC or sham lesions. Neurons categorized as bursting had faster rates of activity than nonbursting cells. AMPH treatment reduced the number of bursts seen in intact rats but increased bursting in lesioned rats. These results suggest that changes in DA firing rate previously found after chronic AMPH may reflect altered patterns of activity. In addition, the effects of long‐term AMPH on the firing patterns of DA neurons appear to be mediated by fibers in the CC. Synapse 38:80–86, 2000. © 2000 Wiley‐Liss, Inc.