Alteration of conditioned emotional response and conditioned taste aversion after neonatal ventral hippocampus lesions in rats.
Sprague-Dawley rats were submitted to bilateral ventral hippocampus lesions 7 days after birth according to the Lipska and Weinberger's procedure for modeling schizophrenia. The aim of the present work was to better characterize their learning capacity. A double latent inhibition study was conducted using respectively conditioned taste aversion and conditioned emotional response. In the background of this evaluation, locomotion under apomorphine and startle reactions, inhibited or not by prepulses, was also evaluated. Our experimental methods were the same as those used in previous studies from the laboratory which were found to be sensitive to pharmacological manipulations and shown by others to be unaffected by lesions of the ventral hippocampus carried out in adult rats. In contrast, neonatally lesioned rats, once adults (over 60 days old), were hyper-responsive to noise--i.e., the startle response to a 105 db(A) noise pulse was enhanced--and hyperactive under apomorphine (0.7 mg/kg). The prepulse inhibition properties of the startle remained unchanged. Lesioned rats showed a deficit but not a suppression of conditioning, similar in both tests, but latent inhibition was preserved. Such observations complement the already known memory deficit produced in this neurodevelopmental model of schizophrenia.
Angst
Marie-Josée
MJ
U666 INSERM, Faculté de Médecine, Université Louis Pasteur, 11, rue Humann, 67085 Strasbourg Cédex, France.
Macedo
Carlos Eduardo
CE
Guiberteau
Thierry
T
Sandner
Guy
G
D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects; D001930:Brain Injuries / Q000473:pathology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003213:Conditioning, Psychological / Q000502:physiology*; D004644:Emotions; D006624:Hippocampus / Q000503:physiopathology*; D007266:Inhibition, Psychological; D008124:Locomotion / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013216:Reflex, Startle / Q000187:drug effects; D013649:Taste
D000697:Central Nervous System Stimulants; D000661:Amphetamine