078 Characterization of alfaxalone-induced seizures in dogs upon emergence from anesthesia Monica R. Metea a , Cory Appleby b , Ken Kearney b a Preclinical Electrophysiology Consulting, Mattapoisett, MA, USA b Charles River Laboratories, Ashland, OH, USA Many drugs intended for anesthesia may also induce seizures during induction or emergence from sedation (e.g propofol, sevoflurane, etc.). Although seizure-like phenomena (SLP) related to sedation are often reported in the clinic, electroencephalographic (EEG) reports are limited, as the clinical situations are mitigated by co-administration of other anesthetics. However, when these events are encountered preclinically, they can seriously hinder the development of an investigational compound, as safety pharmacology tenets require the absence of seizures in establishing a safety margin. Here we present a characterization of seizures noted during emergence from sedation in telemetry-implanted canines administered 3 mg/kg slow bolus alfaxalone (3α hydroxy 5α pregnane 11,20 dione), in order to differ- entiate the onset and morphology of these events from other types of seizures. Alfaxalone is a synthetic neuroactive anesthetic steroid, acting on the GABAA receptor complex, and known to have effects similar to those of propofol. EEG and EMG direct reads and QEEG analyses were conducted on data collected via telemetry and synchronized video from three male and three female beagle dogs implanted with DSI telemetry probes. In all cases, frank seizures or seizurogenic paroxysms occurred upon emergence from sedation, on a background of delta or theta oscillations with frequent burst suppression, which escalated into generalized spike-wave seizures accompanied by tonic-clonic convul- sions. Unlike typical EEG related to generalized seizures, there was no postictal attenuation noted and the animals recovered rapidly. Clinical signs of convulsion during emergence were carefully observed, as uncoordinated myoclonic movements upon awakening from sedation can be mistaken for attempts to regain equilibrium. For all seizures noted, it was concluded that the abnormal EEG events were due to an exacerbation of intrinsic rhythms, especially theta synchrony, and appeared related to EEG activity typical for emergence from sedation. These data could be useful in establishing or broadening the safety margin for investigational anesthetic drugs. As seizurogenic effects are often reported for such compounds, preclinical EEG and efficacy comparisons with established drugs are recommended in order to progress programs in the clinic. doi:10.1016/j.vascn.2018.01.451 079 Inhibition of long-term kindled seizures induced alterations in expression of CD cell surface markers by AC-31B Uzair Nisar, Shabana U. Simjee H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Science, University of Karachi, Karachi, Pakistan A number of processes are thought to contribute to the development of epilepsy including increased excitatory synaptic transmission, neuronal cell death and development of aberrant innervations pattern in part arising from axonal growth. Recent findings indicate that adhesion molecules and their receptors play an important role in each of these processes and thereby are likely to contribute significantly to the underlying epileptogenesis. Among the adhesion molecules, cell surface glycoproteins CD44 and CD90 are reported to be up-regulated after neuronal injury or epilepsy. Focus of this study was to evaluate the effect of classical anticonvul- sants i.e., diazepam and phenytoin and an essential oil of Allium cepa AC-31B on the expression of these markers in the PTZ-induced kindled model of epilepsy. Mice weighing 20–25 gm were subjected to PTZ-induced kindling. Seizure-related behaviors were monitored for 30–45 min following PTZ administration. Once stage 4 seizures were prominent (30–34 days), animals were sacrificed and the brain samples were collected for the determination of CD44 and CD90 expression. The results revealed that AC-31B not only halts the development of epileptogenesis in PTZ-kindled mice but also significantly reduced the expression of CD44 and CD90. These adhesion proteins play critical role in axonal growth and synapto- genesis including processes induced by seizure in adult brain. Among the adhesion molecules, CD44 and to some extent CD90 are upregulated in the epilepsy and it is thought to contribute to the development of epileptogenesis. The AC-31B tested in this study was observed to suppress the expression of both the CD markers and therefore we suggest that it can be effectively used to control the underlying pathology of epileptogenesis. This finding uncovers a potential effect of AC-31B in epileptogenesis and may provide a new therapeutic target that can be harnessed for the prevention of epilepsy development or progression. doi:10.1016/j.vascn.2018.01.452 081 What should be noted when you use neurospheres in the pharmacological experiments—The neurosphere culture period affects the yield of neurons after differentiation Kanako Takahashi a , Hisashi Ohara b , Nozomi Kasahara b , Masahiro Takase b , Kaori Chujo a , Yasunari Kanda a , Yuko Sekino a,c , Mitsuo Tanabe b , Kaoru Sato a a NIHS, Tokyo, Japan b Kitasato University, Tokyo, Japan c University of Tokyo, Tokyo, Japan Neurosphere (NS) culture is the indispensable and practical technique to apply human neurons to drug development because neurospheres can be amplified and stocked. Besides, protocols for mass production of human iPSC-derived neurons from NSs are required. However, little information is available about the correlation between NS culture protocols and the yield of neurons. In this study, we examined whether or not the length of the NS culture period affects the number of neurons after differentiation by using rat NS prepared from E16 telencephalons. Two groups of NSs were used in this study with the culture periods of 11 and 25 days, respectively. Cells dissociated from each NS were differen- tiated in adherent condition. The numbers of neurons, neural stem cells, astrocytes, and radial glial cells on differentiation (diff.) day 1, 3 and 7 were quantified by immunostaining methods. At the start point of differentiation, the number of neurons in 25 day-group was smaller than that in 11 day-group, suggesting that NS culture period affects the cellular composition of NS. The consistent data were also obtained in Western blotting. The expression level of b3 tubulin in 25 day-group was lower than that in 11 day-group, while the expression levels of nestin and GFAP in 25 day-group was higher than that in 11 day-group. The increment rates of neurons from diff. day 3 to 7 were 1.1 times for 11 day-group and 15.1 times for 25 day-group, resulting in the increase in the neuronal number. On the diff. day 3, the percentage of radial glial cells was 52% in 11 day-group and 83% in 25 day-group. EdU incorporation assay (diff. day Abstracts 135