Animal modeling dual diagnosis schizophrenia: sensitization to cocaine in rats with neonatal ventral hippocampal lesions.
BACKGROUND
Increased substance disorder comorbidity in schizophrenia may reflect greater vulnerability to addictive processes because of inherent neurocircuit dysfunction in the schizophrenic brain.


METHODS
To further explore this hypothesis, we used neonatal ventral hippocampal lesions (NVHL) as a rat model of schizophrenia and assessed locomotor sensitization to cocaine (15 mg/kg) in adulthood.


RESULTS
The NVHL animals showed greater activity in response to an initial cocaine injection compared with sham and saline-treated groups. With daily cocaine injections over 7 days, NVHL rats showed elevated locomotor sensitization curves with greater fluctuations in the intersession changes in activity between days 4 and 7. In a single session 4 weeks later, NVHL compared with SHAM rats showed maintenance of cocaine-associated hyperactivity, as if superimposed on long-term sensitization effects present in both groups.


CONCLUSIONS
In a neurodevelopmental model of schizophrenia, the locomotor effects of cocaine were augmented on initial and repeated doses, with emergence of irregularity in sensitization-related changes in activity in the short term and perseverance of augmented effects in the long term. Altered patterns of behavioral sensitization, as a possible correlate of greater addiction vulnerability, can occur as a by-product of neural systems dysfunction responsible for major psychiatric syndromes.
Chambers
R Andrew
RA
Laboratory for Translational Neuroscience of Dual Diagnosis Disorders (RAC), Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA. robchamb@iupui.edu
Taylor
Jane R
JR
D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D019970:Cocaine-Related Disorders / Q000150:complications / Q000503:physiopathology*; D017831:Diagnosis, Dual (Psychiatry) / Q000523:psychology; D004195:Disease Models, Animal; D005260:Female; D006624:Hippocampus / Q000293:injuries* / Q000473:pathology; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D011247:Pregnancy; D051381:Rats; D012559:Schizophrenia / Q000150:complications / Q000473:pathology*; D013997:Time Factors