Lithium Ameliorates Neonatal Isolation Induced Autistic-like Behaviors In Rats

PART1THE ACQUIRED AUTISM ANIMAL MODELESTABLISHED WITH NEONATAL ISOLATION AND THEEFFORT OF LITHIUM ON THE AUTISM-LIKEBEHAVIORObjective: To establish acquired autism model with neonatalIsolation. Behavior tests were used to examine whether they haveautism-like behaviors, and Lithium treatment has effort on the autism-likebehavior or not.Methods: The offspring of Sprague–Dawley rats (SD rat) weredivided into four groups: Ctr group, Iso group, Licl group and Licl+isogroup. From PND1to PND9, the pups of Iso group and Licl+iso groupwere isolated from their mothers and other litters for one hour. Afterisolation, the Licl group and Licl+iso group were subjected to Lithium(2mmol/kg) injection, and the other two groups were received same volumesaline injection. Between PND42and PND56, behavior tests were carriedout. Social interaction ability were examined by an three-chambered social interaction test; self-grooming behavior were tested by a open-field area;the forced swimming experiment was used to detected depression-likebehavior; and the anxiety-like behavior was examined with Elevated plusmaze and Novelty-suppressed feeding test.Results: Isolation male rats spent much more time in objectcompartment compared with control rats, and spent less time in ratcompartment. Isolation female rats had the same results as the male rats.However, Lithium treatment completely rescued the autism-like behavior tocontrol level. Isolation rats displayed significantly higher self-groomingbehavior relative to control during open-field area test, and Lithiumtreatment could restore the abnormal self-grooming behavior to control level.During forced swimming text Isolation rats displayed higherdepression-like behavior, the latency to immobility were shorter thancontrol rats and spent less time for struggling swimming. And Lithiumreversed the depression-like behavior to normal control level. NeonatalIsolation increased anxiety, both the time spent in open arms and entriesinto open arms significantly increased compared with control rats. Duringnovelty-suppressed feeding test, latency to feed and food in-take during testboth decreased markedly compared with control rats. Fortunately Lithiumcompletely rescues the abnormal behaviors.Conclusion: Neonatal Isolation can induce acquired autism-likebehaviors combines with depression-like and anxiety-like behavior, and Lithium can overcome the abnormal behaviors induced by neonatalIsolation. MECHANISM OF NEONATAL ISOLATION INDUCESAUTISM-LIKE BEHAVIOR AND MECHANISM OFLITHIUM’S EFFORT ON AUTISM-LIKE BEHAVIORObjective: To explore the mechanism of neonatal Isolation inducesautism-like behavior and the mechanism of Lithium’s effort on thebehavior.Methods: The groups were same as part1. From PND42to PND44,the SD rats of the four groups were subjected to bromodeoxyuridinem(Brdu,100mg/kg) injection once a day. Twenty-four hours after last BrdUinjection, the animals were deeply anesthetized and perfused with saline and4%paraformaldehyde buffer. The brain tissues were fixed in4%paraformaldehyde for forty-eight hours, then dehydrated with30%sucrosefor forty-eight hours. After that the brain tissues were cut into40-μm thickcoronal sections, every six sections one sections was collected forImmunofluorescence. Positive cells were counted with a Nikon fluorescence microscope, and the positive cells multiplied6to estimate thetotal number of positive cells per rat. From PND35to PND56, the animalswere anesthetized and perfused with NMDG artificial cerebral spinal fluid(ACSF) with95%O2and5%CO2. Rat brains were rapidly taken out andplaced into NMDG ACSF. Coronalhippocampalslices (400μm thickness)were collected and incubated in HEPES ACSF at37℃for1hour.Hippocampal CA1pyramidal neurons were visualized for whole-cellpatch-clamp recordings under infrared/differential interference contrastmicroscopy.Results: The results of Immunofluorescence: DCX positive cells ofrats subjected to Isolation reduced compared with control rats in DG area;Brdu and NeuN double marked cells of Isolation group rats also decreasedcompared with control rats. Notably, Lithium treatment promoted theproliferation of NPCs in the DG of Isolated rats, and restored the number ofnewborn neurons to physiological levels. However, Brdu and GFAP doublemarked cells had no difference between control and Isolation group. Theresults of Electrophysiology: Neonatal Isolation increased inhibitorysynaptic transmission, the amplitude of sIPSC enhanced in Isolation rats,but neonatal Isolation had no effort on the frequency of sIPSC an, theamplitude and frequency of sEPSC. Moreover, Lithium treatment rescued itto physiological level.Conclusion: Disorder of neurogenesis and change of inhibitory neurotransmission may play an important role in autism-like behavior.Lithium may be a potential clinical drug for autism in near future.