Abstract
Distribution and levels of octopamine (OA), one of the biogenic amines in the invertebrate nervous system, may have significant effects on insect physiological processes including growth, feeding and reproduction. In this paper capillary gas chromatography with electron capture detection (GC-ECD) and mass selective detection (GC-MS) were used to determine the content of OA in Blattella germanica L. central nervous system (CNS), and that of OA in cockroach stressed by kinds of insecticides, known octopaminergic agonists and some essential oils. A derivatization method for organic extracts via reaction with pentafluoropropionic anhydride (PFPA) was developed. The resulting OA derivatives were confirmed by GC-MS to be tris-pentafluoropropionyl-OA. The method was used to quantify the amount of OA in insect issues by capillary GC-ECD through an extraction-derivatization-liquid/liquid partition procedure. Average OA content in normal cockroaches was determined to be 68.49 ± 7.31 ng/g tissue (N=5 determinations). It was shown that insecticides including chlordimeform, methomyl, permethrin, chlorfluazuron, malathion, trichlorfon and some oxazolidine agonists, essential oils including eugenol, cinnamic alcohol, phenyl ethyl alcohol could led to significant increase of OA levels in the cockroach CNS comparing with which in insect treated by 1-butanone. Malathion, trichlorfon, chlorfluazuron and cinnamic alcohol were shown to be able to cause a 20- fold increase in OA levels.
Highlights
Octopamine (OA), a biogenic monoamine structurally related to noradrenaline, acts as a neurohormone, a neuromodulator and a neurotransmitter in invertebrates [1]
Though the derivation was already well established for bioamines in urine for GCMS [14], we here report the OA levels in insect tissues by gas chromatography with electron capture detection (GC-electron-capture detector (ECD)) quantization and GCMS confirmation. This derivatization-capillary GC-ECD method was developed to determine the content of OA in cockroach (Blattella germanica L.) central nervous system (CNS), and that of OA in cockroach stressed by representative insecticides, known octopaminergic agonists and some essential oils
Offline derivatization-capillary gas chromatography with electron capture detector (GC-ECD) was developed to determine the content of OA in Blattella germanica L. central nervous system (CNS), and that of OA in cockroach stressed by representative insecticides, known octopaminergic agonists and some essential oils
Summary
Octopamine (OA), a biogenic monoamine structurally related to noradrenaline, acts as a neurohormone, a neuromodulator and a neurotransmitter in invertebrates [1]. Much interest has been drawn on the octopamine and its receptors in the invertebrate nervous system [2,3,4,5]. It has been suggested that distribution and levels of OA have greatly significant effect on insect physiological processes including growth, feeding and reproduction. Davenport et al [9] reported the OA presence in Periplaneta Americana and Schistocerca Americana by a radioenzymatic method. Hirashima et al examined the OA contents in Periplaneta americana, emphasizing the chemical stressors effects [8]. Nusrut reported [14] that the GC-NICI-MS method could detect at least 100pg OA in CNS of Periplaneta Americana. Amendola et al [15] have demonstrated that alcohol and amine groups could be simultaneously reacted with pentafluoropropionic anhydride (PFPA) to form thermo-stable products
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