Repeated quinpirole treatments produce neurochemical sensitization and associated behavioral changes in female hamsters.
BACKGROUND
Repeated stimulation of dopaminergic pathways with dopamine receptor agonists can produce both neurochemical and behavioral sensitization.


OBJECTIVE
The present study was designed to examine whether repeated treatment with the D2-like dopamine receptor agonist, quinpirole, would produce neurochemical sensitization of D1 dopamine receptor-mediated processes and associated behavioral changes in female hamsters in a manner analogous to that previously used to sensitize heterologous dopamine signaling pathways in derived cell lines.


METHODS
Female hamsters received two injections of quinpirole (1.5 mg/kg) or saline each week for 7 weeks, during which time pouching behavior and body weight were monitored. Over the next 2 weeks, hamsters were tested for differences in prepulse inhibition of the acoustic startle response (PPI) and sexual behavior. Adenylate cyclase activation assays were then performed on dissected tissue from the nucleus accumbens and caudate-putamen.


RESULTS
Repeated treatment with quinpirole increased pouching behavior and body weight and disrupted PPI. No changes in sexual activity in response to repeated quinpirole were found. Prior quinpirole treatment enhanced D1 dopamine receptor-stimulated adenylate cyclase activity in the caudate-putamen that was blocked by co-incubation with the D1 dopamine antagonist, SCH23390.


CONCLUSIONS
These results show that repeated activation of D2-like receptors in vivo can produce changes in feeding behavior and sensory processing that is associated with sensitization of D1 dopamine receptor-mediated signaling in the caudate-putamen.
Chester
Julia A
JA
Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907-2081, USA. jchester@psych.purdue.edu
Mullins
Amanda J
AJ
Nguyen
Chau H
CH
Watts
Val J
VJ
Meisel
Robert L
RL
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001552:Benzazepines / Q000494:pharmacology; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism; D006224:Cricetinae; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D010052:Ovariectomy; D011699:Putamen / Q000187:drug effects / Q000378:metabolism; D019257:Quinpirole / Q000494:pharmacology*; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D013216:Reflex, Startle / Q000187:drug effects; D012726:Sexual Behavior, Animal / Q000187:drug effects
D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D000262:Adenylyl Cyclases