PMID- 9335075
OWN - NLM
STAT- MEDLINE
DCOM- 19971114
LR  - 20191210
IS  - 0033-3158 (Print)
IS  - 0033-3158 (Linking)
VI  - 133
IP  - 1
DP  - 1997 Sep
TI  - Differences in extracellular dopamine concentrations in the nucleus accumbens 
      during response-dependent and response-independent cocaine administration in the 
      rat.
PG  - 7-16
AB  - Studies indicate that nucleus accumbens (NAcc) dopamine neurotransmission is 
      involved in the reinforcing and direct effects of cocaine. The present study was 
      initiated to explore further the relationship of NAcc extracellular dopamine 
      concentrations ([DA]e) and cocaine self-administration using a yoked littermate 
      design. In the first experiment, one rat from each litter was trained to 
      self-administer cocaine i.v. (SA: 0.33 mg/inf) under a fixed ratio 2 schedule, 
      while a second rat received simultaneous infusions of cocaine yoked to the 
      infusions of the SA (YC). NAcc [DA]e and cocaine concentrations ([COC]) were 
      assessed during the test sessions using in vivo microdialysis combined with 
      microbore HPLC procedures. [DA]e and [COC] were significantly elevated in the SA 
      and YC groups during the self-administration session; however, [DA]e were greater 
      in the SA group compared to the YC group in the first hour of the session, even 
      though [COC] were not significantly different. On the following day, the rats 
      previously allowed to self-administer cocaine were administered 
      response-independent cocaine infusions yoked to the infusion pattern from the 
      previous day. [DA]e were significantly elevated above baseline levels during the 
      session but were significantly less than concentrations obtained when cocaine was 
      self-administered by these subjects. [COC] during the sessions were not 
      significantly different between the two days. Baseline [DA]e were not 
      significantly different between the SA and YC groups or between Day 1 and Day 2. 
      Furthermore, there was no significant difference in the in vitro probe recovery 
      between one and two days following probe implantation. These results suggest that 
      the context in which cocaine was administered significantly altered the 
      neurochemical response to equivalent brain concentrations of cocaine. NAcc [DA]e 
      was significantly increased when the delivery of cocaine infusions was contingent 
      on the behavior of the rat, indicative of a role in the neural processes 
      underlying cocaine reinforcement.
FAU - Hemby, S E
AU  - Hemby SE
AD  - Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Wake 
      Forest University, Winston-Salem, NC 27157-1083, USA.
FAU - Co, C
AU  - Co C
FAU - Koves, T R
AU  - Koves TR
FAU - Smith, J E
AU  - Smith JE
FAU - Dworkin, S I
AU  - Dworkin SI
LA  - eng
GR  - R01 DA003628/DA/NIDA NIH HHS/United States
GR  - DA-00114/DA/NIDA NIH HHS/United States
GR  - DA-03628/DA/NIDA NIH HHS/United States
GR  - DA-06634/DA/NIDA NIH HHS/United States
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - Germany
TA  - Psychopharmacology (Berl)
JT  - Psychopharmacology
JID - 7608025
RN  - 0 (Narcotics)
RN  - I5Y540LHVR (Cocaine)
RN  - VTD58H1Z2X (Dopamine)
SB  - IM
MH  - Animals
MH  - Cocaine/*pharmacology
MH  - Conditioning, Operant/*physiology
MH  - Dopamine/*metabolism
MH  - Male
MH  - Microdialysis
MH  - Narcotics/*pharmacology
MH  - Nucleus Accumbens/*drug effects/metabolism
MH  - Rats
MH  - Rats, Inbred F344
MH  - *Reinforcement, Psychology
MH  - Self Administration
EDAT- 1997/10/23 00:00
MHDA- 1997/10/23 00:01
CRDT- 1997/10/23 00:00
PHST- 1997/10/23 00:00 [pubmed]
PHST- 1997/10/23 00:01 [medline]
PHST- 1997/10/23 00:00 [entrez]
AID - 10.1007/s002130050365 [doi]
PST - ppublish
SO  - Psychopharmacology (Berl). 1997 Sep;133(1):7-16. doi: 10.1007/s002130050365.