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Key Event Title
Disruption, neurotransmitter release
|Level of Biological Organization|
Key Event Components
Key Event Overview
AOPs Including This Key Event
|AOP Name||Role of event in AOP||Point of Contact||Author Status||OECD Status|
|MEK-ERK1/2 activation leading to deficits in learning and cognition||KeyEvent||Travis Karschnik (send email)||Under development: Not open for comment. Do not cite|
|elavl3, sox10, mbp induced neuronal effects||KeyEvent||Donggon Yoo (send email)||Under development: Not open for comment. Do not cite|
|Birth to < 1 month||Moderate|
Key Event Description
Any of various neurotransmitters or indicators of neurotransmission.
How It Is Measured or Detected
Weighed brain tissues were homogenized in a Potter-Elvehjem type A homogenizer with a teflon pestle using cold acidified n-butanol. The biogenic amines were extracted and estimated according to the procedure of Sadavongvivad (1970). The recovery experiments were done simultaneously. Recoveries for different standards were 92 + 3% for dopamine (DA), 80+ 5% for norepinephrine (NE) and 90 + 5% for 5-hydroxytryptamine (5-HT). Fluorescence was measured in a Aminco SPF-500 spectrofluorometer (Chandra et al., 1981).
BDNF quantitative real-time PCR. Hippocampal neuronal cultures were exposed to normal bath solution or 1.0 or 2.0μM Pb2+ for 5 days, and subsequently RNA was harvested according to manufacturer’s instructions (RNeasy; Qiagen), quantified by reading the absorbance at 260 nm, and converted to complementary DNA (cDNA) using 1 μg RNA according to manufacturer’s instructions (High Capacity Reverse Transcription Kit 4368814; Applied Biosystems). Quantitative real-time PCR (q-rtPCR) was performed in triplicate using TaqMan Gene Expression Assays (Applied Biosystems) with 50 ng cDNA using the following probes: Actin (Rat, Rn00667869_m1; Applied Biosystems) and BDNF exon I, exon II, exon IV, and exon IX (Applied Biosystems). Data were analyzed as previously described (Livak and Schmittgen, 2001), and results were expressed as fold change in gene expression relative to control (Stansfield and others 2012).
BDNF release via ELISA. Sandwich ELISAs were performed on DIV12 cell culture media using the BDNF Emax ImmunoAssay System kit (Promega, Madison, WI) according to the manufacturer’s instructions. BDNF content was interpolated from standard curve runs for each plate (linear range of 7.8–500 pg/ml). BDNF protein content was divided by total protein for each sample to determine the number of picograms of peptide per microgram of total protein (Stansfield and others 2012).
In vivo microdialysis is a well-established method for monitoring the extracellular levels of neurotransmitters in the CNS. This technique has been used extensively in neuroscience for almost 30 years (Westerink 1995; Ungerstedt 1991; Robinson 1991; Benveniste 1989; Benveniste and Huttemeier 1990; Di Chiara 1990). Microdialysis allows online estimates of neurotransmitters in living animals and is a suitable method for monitoring the extracellular levels of neurotransmitters during local administration of pharmacological agents (Hammarlund-Udenaes 2000). Older alternative in vivo methods for the study of neurotransmitter release are the push–pull technique used in the brain, (Singewald and Philippu 1998) spinal cord, (Zachariou and Goldstein 1997) and intrathecal space (Yaksh and Tyce 1980).
Domain of Applicability
Benveniste H, Huttemeier PC. Microdialysis: theory and application. Progr Neurobiol. 1990;35:195.
Benveniste H. Brain microdialysis. J Neurochem. 1989;52:1667.
Chandra, Satya V., et al. "Behavioral and neurochemical changes in rats simultaneously exposed to manganese and lead." Archives of Toxicology 49 (1981): 49-56.
Di Chiara G. In vivo brain dialysis of neurotransmitters. Trends Pharmacol Sci. 1990;11:116.
Hammarlund-Udenaes M. The use of microdialysis in CNS drug delivery studies: pharmacokinetic perspectives and results with analgesics and antiepileptics. Adv Drug Deliv Rev. 2000;45:283.
Kirstie H. Stansfield and others, Dysregulation of BDNF-TrkB Signaling in Developing Hippocampal Neurons by Pb2+: Implications for an Environmental Basis of Neurodevelopmental Disorders, Toxicological Sciences, Volume 127, Issue 1, May 2012, Pages 277–295, https://doi.org/10.1093/toxsci/kfs090
Robinson TJ. Microdialysis in the Neurosciences. Vol. 7. Elsevier; Amsterdam: 1991. Techniques in the behavioral and neural sciences.
Singewald N, Philippu A. Release of neurotransmitters in the locus coeruleus. Progr Neurobiol. 1998;56:237.
Ungerstedt U. Microdialysis: principles and applications for studies in animals and man. J Intern Med. 1991;230:365
Westerink BH. Brain microdialysis and its application for the study of animal behaviour. Behav Brain Res. 1995;70:103.
Yaksh TL, Tyce GM. Resting and K+-evoked release of serotonin and norephinephrine in vivo from the rat and cat spinal cord. Brain Res. 1980;192:133.
Zachariou V, Goldstein BD. Dynorphin-(1-8)inhibits the release of substance P-like immunoreactivity in the spinal cord of rats following a noxious mechanical stimulus. Eur J Pharmacol. 1997;323:159.