title: Melatonin attenuates methamphetamine-induced reduction of tyrosine hydroxylase, synaptophysin and growth-associated protein-43 levels in the neonatal rat brain.
abstract: Methamphetamine (METH) is a most commonly abused drug which damages nerve terminals by causing formation of reactive oxygen species (ROS), apoptosis, and finally neuronal damage. Fetal exposure to neurotoxic METH causes significant behavioral effects. The developing fetus is substantially deficient in most antioxidative enzymes, and may therefore be at high risk from both endogenous and drug-enhanced oxidative stress. Little is known about the effects of METH on vesicular proteins such as synaptophysin and growth-associated protein 43 (GAP-43) in the immature brain. The present study attempted to investigate the effects of METH-induced neurotoxicity in the dopaminergic system of the neonatal rat brain. Neonatal rats were subcutaneously exposed to 5-10mg/kg METH daily from postnatal day 4-10 for 7 consecutive days. The results showed that tyrosine hydroxylase enzyme levels were significantly decreased in the dorsal striatum, prefrontal cortex, nucleus accumbens and substantia nigra, synaptophysin levels decreased in the striatum and prefrontal cortex and growth-associated protein-43 (GAP-43) levels significantly decreased in the nucleus accumbens of neonatal rats. Pretreatment with 2mg/kg melatonin 30 min prior to METH administration prevented METH-induced reduction in tyrosine hydroxylase, synaptophysin and growth-associated protein-43 protein levels in different brain regions. These results suggest that melatonin provides a protective effect against METH-induced nerve terminal degeneration in the immature rat brain probably via its antioxidant properties.
authors.affiliation: Neuro-Behavioral Biology Center, Institute of Science and Technology for Research and Development, Mahidol University, Salaya, Nakornpathom 73170, Thailand.
authors.forename: Sukit
authors.initials: S
authors.lastname: Kaewsuk
authors.forename: Kwankanit
authors.initials: K
authors.lastname: Sae-ung
authors.forename: Pansiri
authors.initials: P
authors.lastname: Phansuwan-Pujito
authors.forename: Piyarat
authors.initials: P
authors.lastname: Govitrapong
mesh_terms: D019969:Amphetamine-Related Disorders / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology; D001921:Brain / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D001923:Brain Chemistry / Q000187:drug effects* / Q000502:physiology; D000697:Central Nervous System Stimulants / Q000009:adverse effects; D004298:Dopamine / Q000096:biosynthesis; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004347:Drug Interactions / Q000502:physiology; D005260:Female; D019922:GAP-43 Protein / Q000187:drug effects / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D008694:Methamphetamine / Q000037:antagonists & inhibitors* / Q000633:toxicity; D018696:Neuroprotective Agents / Q000494:pharmacology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D016708:Synaptophysin / Q000187:drug effects / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000187:drug effects / Q000378:metabolism; D014855:Wallerian Degeneration / Q000139:chemically induced / Q000188:drug therapy / Q000517:prevention & control
chemical_list: D000975:Antioxidants; D000697:Central Nervous System Stimulants; D019922:GAP-43 Protein; D018696:Neuroprotective Agents; D016708:Synaptophysin; D008694:Methamphetamine; D014446:Tyrosine 3-Monooxygenase; D008550:Melatonin; D004298:Dopamine