title: Differences in the structure of drinking, cart expression and dopamine turnover between polydipsic and non polydipsic rats in the quinpirole model of psychotic polydipsia.
abstract: BACKGROUND
  Dopaminergic D2/D3 agonist quinpirole (QNP) elicits nonregulatory drinking in rats, a model of psychotic polydipsia. Why only a fraction of QNP-treated rats responds to the treatment becoming polydipsic is still unclear.
  
  
  OBJECTIVE
  To unveil possible factors contributing to such variability, we analyzed drinking microstructure in saline and QNP-treated rats, the hypothalamic expression of the cocaine and amphetamine regulated transcript (CART), and the monoaminergic turnover in selected brain areas.
  
  
  METHODS
  Rats were daily treated with saline or QNP 0.5 mg/kg, and their 5-h water intake was measured for five consecutive days. The number of bouts and episodes of licking, and their duration, were also measured. Brain CART expression was measured by in situ hybridization and monoamines turnover by HPLC analysis of tissue extracts. Based on the amount of water ingested during the 5-h session, QNP-treated rats were post hoc grouped in polydipsic (PD) and in nonpolydipsic (NPD) rats, and the results compared accordingly.
  
  
  RESULTS
  The number of drinking bouts and episodes increased in PD rats, while NPD rats behaved as the controls. CART expression decreased in the arcuate nucleus of the hypothalamus of the PD rats. In contrast, both PD and NPD rats showed a reduction of DA turnover in both ventral tegmental area (VTA) and nucleus accumbens (NAcc). No difference was detected in the turnover of 5HT and NA.
  
  
  CONCLUSIONS
  Microstructure analysis confirms that QNP acts on the appetitive component of drinking behavior, making it compulsive. CART expression reduction in response to dopaminergic hyperstimulation might sustain excessive drinking in PD rats.
authors.affiliation: Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, 5 Piazzale Aldo Moro, 00185, Rome, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Schepisi
authors.forename: Silvia
authors.initials: S
authors.lastname: Cianci
authors.forename: Gaurav
authors.initials: G
authors.lastname: Bedse
authors.forename: Jin
authors.initials: J
authors.lastname: Fu
authors.forename: Silvana
authors.initials: S
authors.lastname: Gaetani
authors.forename: Paolo
authors.initials: P
authors.lastname: Nencini
mesh_terms: D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000633:toxicity; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D059606:Polydipsia / Q000139:chemically induced / Q000378:metabolism; D059607:Polydipsia, Psychogenic / Q000139:chemically induced* / Q000378:metabolism*; D019257:Quinpirole / Q000008:administration & dosage* / Q000633:toxicity; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D018491:Dopamine Agonists; D009419:Nerve Tissue Proteins; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D019257:Quinpirole; D004298:Dopamine