Enriched environment prevents cognitive and motor deficits associated with postnatal MK-801 treatment.
BACKGROUND
Previous studies have shown the beneficial effects of enriched environment (EE) in rescuing behavioral deficits such as pre-pulse inhibition and locomotor hyperactivity associated with N-methyl-D-aspartate (NMDA) receptor blockade; however, cognitive deficits remain unresponsive.


OBJECTIVE
We designed experiments to determine the consequences of raising rat pups in an EE on several behavioral aberrations, mainly cognitive deficits, observed in rats postnatally exposed to MK-801 (NMDA receptor antagonist).


METHODS
Male Wistar rats were injected with MK-801 (1 mg/kg) from postnatal day (P) 6-10. Rat pups were housed in an EE from birth up to the time of behavioral experiments at P28-34. The effects of EE in correcting MK-801-associated behaviors were assessed by rotarod, wire grip, open filed, and Morris water maze tests.


RESULTS
We found that EE not only has beneficial effects on cognitive performance of normal rats but also prevents spatial learning and memory deficits in Morris water maze induced by MK-801. Postnatal MK-801 treatment also led to motor deficits both in wire grip and accelerating rotarod tests. These deficits were not observed in MK-801-treated rats raised in EE. In the open field test, EE prevented increase in "frequency of grooming" and decrease in "time spent in the center" associated with MK-801.


CONCLUSIONS
Our results suggest that exposure to an EE would be strongly beneficial in correcting deficits, notably cognitive, associated with MK-801. Given that the postnatal MK-801 treatment represents an animal model of schizophrenia, we propose timely environmental interventions might be an effective strategy in the protection against schizophrenia.
Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran.
Masoumeh
M
Nozari
Mohammad
M
Shabani
Mahdieh
M
Hadadi
Nafiseh
N
Atapour
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D003072:Cognition Disorders / Q000139:chemically induced / Q000517:prevention & control*; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004777:Environment; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate