Motivational responses to natural and drug rewards in rats with neonatal ventral hippocampal lesions: An animal model of dual diagnosis schizophrenia

R. Chambers, David W. Self

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

The high prevalence of substance use disorders in schizophrenia relative to the general population and other psychiatric diagnoses could result from developmental neuropathology in hippocampal and cortical structures that underlie schizophrenia. In this study, we tested the effects of neonatal ventral hippocampal lesions on instrumental behavior reinforced by sucrose pellets and intravenous cocaine injections. Lesioned rats acquired sucrose self-administration faster than sham-lesioned rats, but rates of extinction were not altered. Lesioned rats also responded at higher rates during acquisition of cocaine self-administration, and tended to acquire self-administration faster. Higher response rates reflected perseveration of responding during the post-injection "time-out" periods, and a greater incidence of binge-like cocaine intake, which persisted even after cocaine self-administration stabilized. In contrast to sucrose, extinction from cocaine self-administration was prolonged in lesioned rats, and reinstatement of cocaine seeking induced by cocaine priming increased compared with shams. These results suggest that neonatal ventral hippocampal lesions facilitate instrumental learning for both natural and drug rewards, and reduce inhibitory control over cocaine taking while promoting cocaine seeking and relapse after withdrawal. The findings are discussed in terms of possible developmental or direct effects of the lesions, and both positive reinforcement (substance use vulnerability as a primary disease symptom) and negative reinforcement (self-medication) theories of substance use comorbidity in schizophrenia.

Original languageEnglish (US)
Pages (from-to)889-905
Number of pages17
JournalNeuropsychopharmacology
Volume27
Issue number6
DOIs
StatePublished - Dec 1 2002
Externally publishedYes

Fingerprint

Dual (Psychiatry) Diagnosis
Reward
Cocaine
Schizophrenia
Animal Models
Self Administration
Pharmaceutical Preparations
Sucrose
Operant Conditioning
Self Medication
Mental Disorders
Intravenous Injections
Substance-Related Disorders
Comorbidity
Recurrence

Keywords

  • Addiction
  • Dopamine
  • Dual diagnosis
  • Hippocampus
  • Nucleus accumbens
  • Schizophrenia

ASJC Scopus subject areas

  • Pharmacology

Cite this

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