Critical period exists in the effects of isolation rearing on sensorimotor gating function but not locomotor activity in rat

• Published in: Progress in neuro-psychopharmacology & biological psychiatry 2011-06, Vol.35 (4), p.1068-1073
• Main Authors: Liu, Yia-Ping, Kao, Yu-Chen, Tung, Che-Se
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; Adult and adolescent clinical studies; Animals; Biological and medical sciences; Critical Period (Psychology); Dizocilpine Maleate - administration & dosage; Dizocilpine Maleate - pharmacology; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists - administration & dosage; Excitatory Amino Acid Antagonists - pharmacology; Isolation rearing; Locomotor activity; Male; Medical sciences; MK-801; Motor Activity - drug effects; Motor Activity - physiology; Neuropharmacology; Pharmacology. Drug treatments; Pre-pulse inhibition; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychoses; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate - drug effects; Receptors, N-Methyl-D-Aspartate - physiology; Reflex, Startle - drug effects; Reflex, Startle - physiology; Schizophrenia; Sensory Gating - drug effects; Sensory Gating - physiology; Social Isolation - psychology
• ISSN: 0278-5846; 1878-4216
• DOI: 10.1016/j.pnpbp.2011.03.002

Isolation-reared (IR) rats exhibit various cognitive and behavioral abnormalities in adulthood of which locomotor hyperactivity and impaired prepulse inhibition (PPI) of an acoustic startle reflex are the two cardinal characteristics. Using an amended social deprivation–resocialization paradigm, the present study examined the role of the developmental specificity of the effects of IR and its interaction with the non-competitive NMDA receptor antagonist, MK-801. Locomotor activity and PPI were measured in three groups of adult rats: social control, IR throughout life, and IR for the first two weeks after weaning followed by social housing. MK-801 was injected intraperitoneally (i.p.) 30 min prior to testing at doses of 0, 0.02, 0.1, and 0.2 mg/kg. The results revealed that locomotor activity increased only in rats in the IR throughout life group but not in the other two groups. The impairment of PPI was seen in rats in the IR for the first two weeks and the IR throughout life groups. Furthermore, the effect of MK-801 on PPI was bidirectional in rats of the IR for the first two weeks and IR throughout life groups but not in the social control group. These results suggest that the IR-induced behavioral effects are developed distinctively in terms of the critical period hypothesis, which strengthens the developmental hypothesis of schizophrenic-like dysfunctions. ► An amended social deprivation–resocialization paradigm was used. ► Gating dysfunction but not locomotion was more developmentally specific. ► NMDA receptors were involved in the isolation-rearing induced abnormalities.