地卓西平马来酸盐动物行为模型研究

目的 制作灵长类动物从氨酸Ｎ－甲基－天冬氨酸受体非竞争性拮抗剂地产马来酸盐（ＭＫ－８０１）功能低下行为模型：研究奥氮平治疗谷氨酸功能低下的疗效。方法：给Ｃｅｂｕｓ Ａｐｅｌｌａ猴皮下注射ＭＫ－８０１（０．０６ｍｇ／ｋｇ,０．０８ｍｇ／ｋｇ,０．１０ｍｇ／ｋｇ）或／和奥氮平（０．０２ｍｇ／ｋｇ,０．０４ｍｇ／ｋｇ,０．０８ｍｇ／ｋｇ）,用自编７分量表评定药物所致动物的行为变化。结果 注射药物３ｈ内动     

地卓西平马来酸盐对抑郁大鼠行为学和前额叶BDNF表达的影响

目的观察地卓西平马来酸盐(MK-801)预处理对利血平诱导的抑郁模型大鼠抑郁行为的改善作用及大脑前额叶脑源性神经营养因子(BDNF)表达的影响。方法采用随机数字表法将32只成年雄性SD大鼠分为4组:对照组、利血平模型组、MK-801+利血平组和MK-801组,每组8只。MK-801+利血平组和MK-801组预先给予腹腔注射MK-801(0.3 mg/kg),对照组和利血平模型组腹腔注射相应体积的生理盐水。30 min后,利血平模型组和MK-801+利血平组腹腔注射利血平(4 mg/kg),对照组和MK-801组腹腔注射相同体积的乙酸溶剂。注射利血平48 h后利用强迫游泳实验观察大鼠的抑郁样行为表现,并在行为实验完成后处死大鼠,以酶联免疫吸附实验(ELISA)检测大脑前额叶BDNF的表达水平。结果在强迫游泳实验中,利血平模型组强迫游泳不动时间[(49.38±7.85)s]长于对照组[(15.59±5.43)s],差异有统计学意义(t=11.91,P0.01);MK-801+利血平组强迫游泳不动时间[(12.32±4.25)s]短于利血平模型组,差异有统计学意义(t=13.06,P0.05)。ELISA结果显示,利血平模型组前额叶BDNF表达水平[(10.09±0.88)ng/mL]低于对照组[(13.29±1.10)ng/mL],差异有统计学意义(t=6.44,P0.01);MK-801+利血平组大鼠前额叶的BDNF表达水平[(12.56±1.83)ng/mL]高于利血平模型组,差异有统计学意义(t=3.44,P0.05)。结论 MK-801可改善大鼠的抑郁样行为,其机制可能与调节脑内BDNF的表达有关。     

地卓西平马来酸盐精神分裂症模型大鼠前额叶皮质与外周神经调节蛋白-1基因表达的关系

目的 了解SD大鼠神经调节蛋白-1(Nrg1)基因mRNA在地卓西平马来酸盐(MK-801)作用下的表达变化及氯氮平干预的影响,初步探讨Nrg1基因mRNA在大鼠前额叶皮质和外周表达变化关系.方法 采用MK-801对66只清洁级雄性SD大鼠建立大鼠精神分裂症模型,分为模型组(30只)、对照组(30只)和干预组(6只).采用SMART小动物行为视频分析系统测定3组大鼠的自发活动,并对大鼠刻板行为和共济失调等行为进行评分;应用实时荧光定量逆转录-聚合酶链反应同时检测不同时间点3组大鼠中枢前额叶皮质与外周血淋巴细胞Nrg1基因mRNA的表达水平.结果 3组大鼠自发活动结果、共济失调评分、刻板行为评分差异均有统计学意义(F=14.903,P=0.000;F =76.196,P=0.000;F =72.654,P=0.000).与对照组比较,模型组外周总Nrg1 mRNA(t=2.779,P=0.019)和前额叶皮质人神经调节蛋白(Hrg) mRNA(t=2.293,P=0.045)在药物作用90 min时表达增高,外周胶质生长因子(Ggf) mRNA在120m in时表达增高(t=2.728,P=0.035);在90 min时,干预组外周Ggf mRNA(F=4.484,P=0.030)表达低于模型组,模型组前额叶皮质HrgmRNA(F =4.238,P=0.035)的表达高于对照组和干预组,模型组和对照组前额叶皮质感觉-运动神经元衍生因子mRNA(F =4.739,P=0.025)的表达高于干预组.大鼠自身前额叶皮质与外周血淋巴细胞中总Nrg1 mRNA表达呈正相关(r=0.252,P=0.041).结论 MK-801可以影响部分Nrg1亚型mRNA表达,氯氮平能够部分减弱这种影响;大鼠总Nrg1 mRNA外周与前额叶皮质的表达具有一致性,外周血总Nrg1 mRNA表达情况可以在一定程度上反映前额叶皮质的变化.     

急慢性注射地卓西平马来酸盐对小鼠额叶microRNA-181b表达的影响

目的研究急慢性注射地卓西平马来酸盐(MK-801)对小鼠额叶中与精神分裂症相关的微小RNA(microRNA,miRNA)-181b表达的影响,探讨其参与精神分裂症病理学的可能机制。方法急性注射实验中40只小鼠随机分成四组,分别腹腔注射不同剂量(0.125 mg/kg,0.25 mg/kg,0.50 mg/kg)的MK-801和生理盐水(简称急性对照组),15 min后用实时荧光定量PCR(real-time PCR)技术检测额叶miRNA-181b的相对表达量;慢性注射实验中22只小鼠随机分成两组,分别腹腔注射0.25 mg.kg-1.d-1的MK-801和生理盐水(简称慢性对照组),连续14 d,然后检测miRNA-181b的相对表达量。结果急性注射0.125 mg/kg、0.25 mg/kg、0.50 mg/kgMK-801的各组小鼠额叶miRNA-181b的相对表达水平分别为0.65±0.05、0.61±0.05和0.91±0.08。前两个剂量组miRNA-181b的表达明显低于对照组(1.00±0.13),P<0.05,而0.5 mg/kg的MK-801则对miRNA-181b表达无影响(P>0.05)。慢性MK-801注射组miRNA-181b的相对表达量为1.86±0.19,显著高于慢性对照组(1.00±0.10),P<0.05。结论急性和慢性MK-801对额叶中miRNA-181b表达的影响不同,结合miR-181b的分子功能,提示miRNA-181b在急性和慢性模型鼠的构建中起到不同的作用。     

氟哌啶醇对MK-801致小鼠高活动性与前脉冲抑制损害的作用

目的观察氟哌啶醇对谷氨酸功能低下小鼠模型表现出的高活动性及前脉冲抑制(prepulse inhibition,PPI)损害的作用。方法昆明种小鼠152只分组(n=8或n=10)进行下述对照观察:观察不同剂量氟哌啶醇(0.03、0.1、0.3 mg/kg)腹腔注射对昆明种小鼠探究行为和自主活动的影响;以0.25 mg/kg MK-801诱导小鼠自主活动增加,观察上述剂量氟哌啶醇对MK-801致小鼠高活动性的影响;以0.5 mg/kg MK-801诱导小鼠PPI损害,观察氟哌啶醇(0.1、0.3、1 mg/kg)对基线水平PPI以及MK-801损害后PPI的作用。结果与对照组比较,氟哌啶醇剂量为0.1 mg/kg和0.3 mg/kg时,小鼠的探究行为及自主活动总路程减少(P<0.05);但剂量为0.03 mg/kg时,对小鼠的探究行为及自主活动均无影响(P>0.05)。氟哌啶醇剂量为0.1~0.3 mg/kg时,呈剂量依赖性抑制由MK-801引起的自主活动增加(F=27.23,P<0.01),0.1mg/kg的氟哌啶醇的抑制程度为22%(P<0.01),0.3 mg/kg的氟哌啶醇的抑制程度为65%(P<0.00...     

小剂量MK-801对大鼠参照记忆、空间工作记忆和逆反学习能力的影响

目的 探讨腹腔注射N-甲基-D-天冬氨酸 (NMDA )受体拮抗剂地卓西平马来酸盐(MK-801)对大鼠认知功能的影响.方法 成年雄性SD大鼠随机分为MK-801组和对照组,分别腹腔注射小剂量生理盐水或MK-801(0.1 mg/kg)20 min后在Morris水迷宫中评定MK-801对大鼠参照记忆、空间工作记忆和逆反学习能力的影响.结果 参照记忆任务中,与对照组相比MK-801组逃避潜伏期延长(P<0.05),且在目标象限的探索时间百分比[(22.7±2.9)%]与相邻象限[(24.0±0.9)%]和对立象限[(29.3±2.4)%]的差异无统计学意义 (P>0.05);空间工作记忆任务中,对照组匹配试次潜伏期显著短于样本试次[(37.6±6.0) vs (61.5±6.3),P<0.05],而MK-801组两试次潜伏期差异无统计学意义[(53.8±7.8) vs (62.2±7.1),P>0.05];逆反学习任务中,与对照组相比MK-801组潜伏期明显延长(P<0.05),且在空间探索中新旧目标象限探索时间百分比差值小于对照组[(-0.01±4.7) vs (23.5±6.2),P<0.01].结论 腹腔注射小剂量MK-801破坏了大鼠的参照记忆、空间工作记忆和逆反学习,提示其在多个认知维度上可模拟精神分裂症患者的认知缺陷.     

奥氮平对谷氨酸功能低下的精神分裂症小鼠模型的作用

目的 观察奥氮平对谷氨酸功能低下小鼠模型表现出的高活动性及前脉冲抑制(PPI)缺失的作用.方法 昆明种小鼠165只.(1)取36只小鼠分为4组:溶媒空白对照组(腹腔注射溶媒,以下简称对照组),3种奥氮平剂量(0.1 mg/kg体质量,0.2 mg/kg体质量,0.3 mg/kg体质量,腹腔注射)组,每组8～10只;观察奥氮平对小鼠探究行为和自主活动的影响.(2)取49只小鼠分为5组:对照组,地卓西平马来酸盐(MK-801)模型组(溶媒+MK-801,0.25 mg/kg体质量,腹腔注射),3种剂量(同上)奥氮平干预组(奥氮平+MK-801 0.25 mg/kg体质量,腹腔注射),每组9～10只;观察奥氮平对MK-801致小鼠自主活动增加的影响.(3)取80只小鼠分为8组:对照组,MK-801模型组(溶媒+MK-801,0.5 mg/kg体质量,腹腔注射),3种奥氮平剂量给药组(奥氮平+生理盐水,奥氮平剂量分别为0.3 mg/kg体质量,1 mg/kg体质量,3 mg/kg体质量),3种奥氮平剂量(同上)干预组(奥氮平+MK-801 0.5 mg/kg体质量,腹腔注射),每组10只;观察奥氮平对基线前脉冲抑制(PPI)及MK-801引起的PPI缺失的影响.结果 (1)与对照组比较,奥氮平剂量为0.2 mg/kg体质量和0.3mg/kg体质量时,小鼠的探究行为及自主活动总路程减少(P均＜0.05);但剂量为0.1 mg/kg时,对小鼠的探究行为(P=0.363)及自主活动(P=0.196)无影响.(2)奥氮平剂量为0.1～0.3 mg/kg体质量时,呈剂量依赖性抑制MK-801引起的自主活动增加(P均＜0.05).(3)奥氮平剂量为0.3～3mg/kg体质量时,对基线的PPI无影响(P均＞0.05),剂量为1～3 mg/kg时呈剂量依赖性修复了MK-801引起的PPI缺失(P均＜0.05).结论 奥氮平能够特异性地抑制谷氨酸功能低下小鼠模型表现出的高活动性和PPI缺失,与奥氮平的临床药理作用一致.     

奥氮平对谷氨酸功能低下的精神分裂症小鼠模型的作用

Objective To investigate the effects of olanzapine on hyperlocomotion and deficient prepusle inhibition (PPI) of hypoglutamatergic schizophrenia model in mice produced by dizocilpine maleate (MK-801), an N-methyl-D-aspartate (NMDA)antagonist.Methods (1) To investigate the effects of olanzapine on explorative behavior and spontaneous activity, three doses of olanzapine ( 0.1, 0.2, 0.3 mg/kg, i.p.) or vehicle was injected 30 min before the test.Locomotor activity was recorded for 30 min with an automated video tracking system, in which the components of the locomotor activity were divided into exploration (the first 10 min) and spontaneous activity (the second 20 min).(2) To examine the effects of olanzapine on MK-801-induced hyperlocomotion, mice were administered with olanzapine (0.1, 0.2 and 0.3 mg/kg) or vehicle 5 min before administration of MK-801 (0.25 mg/kg).After the second injection, locomotor activity was recorded for 90 min by the video tracking system.( 3 ) To explore the effects of olanzapine on intact and MK-801-disrupted sensorimotor gating, olanzapine (0.3, 1,3 mg/kg, i.p.) or the vehicle were injected 35 min before the start of the experiment, MK-801 (0.5 mg/kg, i.p.) or the same volume of saline was administered 5 min before the PPI experiment.Results ( 1 ) Olanzapine (0.2 and 0.3 mg/kg) significantly inhibited the explorative behavior and spontaneous activity (P ＜ 0.05 ) .Olanzapine at 0.1 mg/kg did not affect exploration ( P = 0.363 ) and spontaneous activity ( P = 0.196 ).Olanzapine (0.1 - 0.3 mg/kg) dose-dependently antagonized MK-801 -induced hyperlocomotion.(2) None of the olanzapine doses tested had a significant effect on baseline PPI.Olanzapine ( 1 - 3 mg/kg) dosedependently restored the MK-801-induced deficits in PPI.Conclusion Olanzapine specifically inhibited the MK-801-induced hyperlocomotion and deficits in PPI in mice and the results are also consistent with clinical findings.     

奥氮平对谷氨酸功能低下的精神分裂症小鼠模型的作用

Objective To investigate the effects of olanzapine on hyperlocomotion and deficient prepusle inhibition (PPI) of hypoglutamatergic schizophrenia model in mice produced by dizocilpine maleate (MK-801), an N-methyl-D-aspartate (NMDA)antagonist.Methods (1) To investigate the effects of olanzapine on explorative behavior and spontaneous activity, three doses of olanzapine ( 0.1, 0.2, 0.3 mg/kg, i.p.) or vehicle was injected 30 min before the test.Locomotor activity was recorded for 30 min with an automated video tracking system, in which the components of the locomotor activity were divided into exploration (the first 10 min) and spontaneous activity (the second 20 min).(2) To examine the effects of olanzapine on MK-801-induced hyperlocomotion, mice were administered with olanzapine (0.1, 0.2 and 0.3 mg/kg) or vehicle 5 min before administration of MK-801 (0.25 mg/kg).After the second injection, locomotor activity was recorded for 90 min by the video tracking system.( 3 ) To explore the effects of olanzapine on intact and MK-801-disrupted sensorimotor gating, olanzapine (0.3, 1,3 mg/kg, i.p.) or the vehicle were injected 35 min before the start of the experiment, MK-801 (0.5 mg/kg, i.p.) or the same volume of saline was administered 5 min before the PPI experiment.Results ( 1 ) Olanzapine (0.2 and 0.3 mg/kg) significantly inhibited the explorative behavior and spontaneous activity (P ＜ 0.05 ) .Olanzapine at 0.1 mg/kg did not affect exploration ( P = 0.363 ) and spontaneous activity ( P = 0.196 ).Olanzapine (0.1 - 0.3 mg/kg) dose-dependently antagonized MK-801 -induced hyperlocomotion.(2) None of the olanzapine doses tested had a significant effect on baseline PPI.Olanzapine ( 1 - 3 mg/kg) dosedependently restored the MK-801-induced deficits in PPI.Conclusion Olanzapine specifically inhibited the MK-801-induced hyperlocomotion and deficits in PPI in mice and the results are also consistent with clinical findings.     

Prenatal protein deprivation in rats induces changes in prepulse inhibition and NMDA receptor binding

Epidemiological studies suggest that prenatal malnutrition increases the risk of developing schizophrenia. Animal models indicate that prenatal protein deprivation (PPD) affects many aspects of adult brain function. We tested the hypothesis that PPD in rats would alter prepulse inhibition (PPI), which is an operational measure of sensorimotor gating that is deficient in schizophrenia patients. Additionally, we examined dopaminergic and glutaminergic receptor binding in the striatum and hippocampus, which have been suggested to play a role in the etiology of schizophrenia. Rat dams were fed normal (25%) or low (6%) protein diets beginning 5 weeks prior to, and throughout pregnancy. The pups were tested at postnatal days (PND) 35 and 56 for PPI. Striatal and hippocampal NMDA receptor, and striatal dopamine receptor binding were quantified post-mortem in a subset of these rats. Female rats exposed to PPD had reduced levels of PPI at PND 56, but not PND 35, suggesting the emergence of a sensorimotor gating deficit in early adulthood. Striatal NMDA receptor binding was increased in PPD females. A decrease in initial startle response (SR) was also observed in all PPD rats relative to control rats. These results suggest that PPD causes age- and sex-dependent decreases in PPI and increases in NMDA receptor binding. This animal model may be useful for the investigation of neurodevelopmental changes that are associated with schizophrenia in humans.     

Post-weaning handling attenuates isolation-rearing induced disruptions of prepulse inhibition in rats

Isolation rearing is a developmentally specific non-pharmacological manipulation in rats that produces a deficit in sensorimotor gating, as measured by prepulse inhibition (PPI) of the startle reflex. Previous research has demonstrated that the isolation rearing effect on PPI is sensitive to several factors, including the time of testing with respect to length of isolation, prepulse intensities used, strain of rats, and type of housing environment. This study tested whether handling is another factor that interacts with the isolation-rearing paradigm in PPI. Rats were housed either in the social (three rats per cage) or isolate (one rat per cage) conditions and were handled either 1–2 times per week (minimal handling) or on a daily basis (daily handling). All rats were then tested at 8 and 10 weeks post-weaning. There was an interaction between housing and handling. In the minimal handling condition, isolation rearing produced a deficit in PPI. This effect was absent, however, in the daily handling condition. Thus, regular handling of rats may interfere with the observation of the isolation rearing effect on PPI and should be carefully controlled in studies using this animal model of PPI deficits.     

Effects of typical and atypical antipsychotics on prepulse inhibition and latent inhibition in chronic schizophrenia.

BACKGROUND: Prepulse inhibition and latent inhibition are the two animal paradigms currently dominating neuropharmacological research on attentional deficits in schizophrenia. Both paradigms have been shown to have a reasonable amount of face, predictive, and construct validity, but responsiveness to typical and atypical antipsychotics differs between the two, as indicated by animal and human studies. The relationship between the paradigms in schizophrenic patients is still unclear.METHODS: We tested prepulse inhibition and auditory latent inhibition in a sample of 33 chronic schizophrenic patients medicated either with atypical (n = 17) or typical (n = 16) antipsychotics.RESULTS: Latent inhibition was found to be intact in both patient groups. Prepulse inhibition was intact in the group receiving atypicals, but deficient in the group receiving typicals (at 60 msec lead interval condition).CONCLUSIONS: The direct comparison supports the hypothesis that atypical and typical antipsychotics have different effects on prepulse inhibition than on latent inhibition in schizophrenic patients; however, the results may also be explained by a greater sensitivity of the prepulse inhibition method. Because it is crucial to understand why there are considerable differences between the two paradigms and between human and animal studies, research should focus more strongly on comparative approaches.     

Top–down modulation of prepulse inhibition of the startle reflex in humans and rats

Prepulse inhibition (PPI) is the attenuation of the startle reflex when the sudden intense startling stimulus is shortly preceded by a weaker, non-startling sensory stimulus (prepulse). PPI reflects a protective function of reducing disruptive influences to the processing of prepulse signals and is recognized as a model of sensorimotor gating. In humans, PPI is modulated by both attentional and emotional responses to prepulse, indicating that this early-stage gating is top–down modulated by higher-order cognitive processes. Recent studies have confirmed top–down modulation of PPI in animals, because PPI in rats is enhanced by auditory fear conditioning and perceived separation between fear-conditioned prepulse and masker. This review summarizes recent studies of top–down modulation of PPI conducted in humans and those in rats. Since both baseline PPI and attentional modulation of PPI in patients with schizophrenia are impaired, and both baseline PPI and conditional modulation of PPI in rats with isolation rearing are impaired, this review emphasizes that investigation of top–down modulation of PPI is critical for establishing new animal models for studying both cognitive features and neural bases of schizophrenia. Deficits in either baseline PPI or attentional modulation of PPI in either patients with attention-deficit/hyperactivity disorder (ADHD) or ADHD-modeling rats are also discussed.     

A large single ethnicity study of prepulse inhibition in schizophrenia: Separate analysis by sex focusing on effect of symptoms

Deficits in sensorimotor gating, as measured with prepulse inhibition (PPI), have been considered an endophenotype of schizophrenia. However, the question remains whether these deficits are related to current symptoms. This single site study aimed to explore clinical features related to the modulation of startle reflex in a large sample of Japanese patients with schizophrenia (DSM-IV). The subjects comprised 181 patients and 250 healthy controls matched for age and sex. Schizophrenia symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS). Startle reflex to acoustic stimuli was recorded using a startle stimulus of 115 dB and a prepulse of four different conditions (intensity: 86 dB or 90 dB; lead interval: 60 ms or 120 ms). Patients exhibited significantly reduced startle magnitude (p < 0.001), habituation (p = 0.001), and PPI (90 dB, 60 ms, p = 0.016; 90 dB, 120 ms, p = 0.001) compared with controls. Patients of both sexes exhibited significantly lower habituation and PPI (90 dB, 120 ms) compared with the same sex controls. We could not detect a significant correlation with any clinical variable in the entire patients, however, when men and women were examined separately, there was a negative correlation with the PANSS cognitive domain (ρ = −0.33, p = 0.008) in men, but not in women. Moreover, when patients were subdivided into four clusters, two clusters with high positive symptoms showed significant PPI deficits in men. Our results suggest that sensorimotor gating is impaired in schizophrenia of both sexes, and PPI deficits may be related to thought disturbance and disorganization in male patients with schizophrenia.     

DOI disrupts prepulse inhibition of startle in rats via 5-HT2A receptors in the ventral pallidum

Serotonin (5-HT)_2A receptors are known to be involved in prepulse inhibition of the startle response (PPI), a measure of sensorimotor inhibition that is deficient in schizophrenia, Huntington's disease, and obsessive compulsive disorder. In the present studies, the localization of the 5-HT_2A receptors responsible for modulating PPI was investigated using central injections of the hallucinogenic 5-HT₂ agonist DOI and the novel 5-HT_2A antagonist MDL 100,907. 5-HT_2A receptors are densely localized in the nucleus accumbens (NAC) and the ventral pallidum (VP), areas known to be important components of neural circuitry that mediates the ventral forebrain modulation of PPI. In the present studies, it was found that the infusion of DOI (0.0–5.0 μg/0.5 μl) into the VP disrupted PPI without having effects on startle reactivity. In contrast, similar infusions into the NAC had no effect on PPI or startle reactivity. The infusion of MDL 100,907 into the VP was found to increase PPI by itself and to attenuate the PPI-disruptive effects of systemically administered DOI. It is concluded that 5-HT_2A receptors within the VP are important for the modulation of PPI, presumably through interactions at intrinsic GABAergic or cholinergic interneurons.     

Lesions of the nucleus basalis magnocellularis do not impair prepulse inhibition and latent inhibition of fear-potentiated startle in the rat

The present study tested if lesions of the nucleus basalis magnocellularis (NBM) affect prepulse inhibition (PPI) of the acoustic startle response and latent inhibition (LI) of fear-potentiated startle. The NBM is known to play an important role in learning and memory. Recently, the interest of research focused on its role in attentional and response selection processes. We here tested the effect of excitotoxic NBM-lesions on PPI, a phenomenon of sensorimotor gating that occurs at early stages of information processing. We also assessed the lesion effects on LI, a phenomenon of reduced conditioning after stimulus preexposure that can be used to measure selective attention. Bilateral infusions into the NBM of 80 nmol of quinolinic acid markedly reduced the number of choline acetyltransferase immunopositive neurons in the NBM and lead to a pronounced reduction of acetylcholine esterase in the cortex and the amygdala. However, no effects on PPI, fear-conditioning, or LI of fear-potentiated startle were found. Therefore, we conclude that there is no NBM-driven attentional or response selection process involved in PPI. Furthermore, the simple association learning in the classical conditioning paradigm used for fear-potentiated startle or LI is unaffected by NBM-lesions.     

Lack of association between prepulse inhibition and antisaccadic deficits in chronic schizophrenia: implications for identification of schizophrenia endophenotypes

Individuals with schizophrenia, compared to healthy individuals, are known to exhibit deficient prepulse inhibition (PPI) of the startle response as well as reduced performance on the antisaccade task. There is evidence for genetic transmission of both PPI and antisaccadic abnormalities in schizophrenia. It has been suggested that PPI and antisaccade measures identify separate endophenotypes, on the basis of a lack of relationship between PPI and antisaccade deficits in patients with schizotypal personality disorder. However, given that patients with schizotypal personality disorder are unlikely to manifest all the abnormalities associated with schizophrenia, it is important to determine that there is no relationship present between these two abnormalities in people affected with schizophrenia. The main objective of this investigation therefore was to establish the lack of the association between PPI and antisaccade deficits in schizophrenia in two independent studies. Study 1 involved 39 patients with schizophrenia and 14 healthy controls and study 2 involved 35 patients with schizophrenia and 22 healthy controls. PPI (uninstructed paradigm) of the acoustically elicited startle (eye blink) was measured electromyographically. Antisaccadic eye movements (standard, non-overlap version) were measured using infrared oculography. Patients displayed reduced PPI and a lower percentage of correct antisaccades relative to healthy controls in both studies. As expected, no relationship occurred between PPI and the percentage of correct antisaccade responses in either group. It is concluded that PPI and antisaccade abnormalities in schizophrenia represent separate endophenotypes, reflecting the functions of different genetic aetiologies and different or only partially overlapping neural systems.