Octopamine Biogenic amines

Biogenic amines are of great interest to researchers because of their potential roles in several psychiatric and neurological disorders. They include dopamine (DA), noradrenaline (NA), 5-hydroxytryptamine (5-HT, serotonin), histamine, and trace amines such as 2-phenylethylamine (PEA), tyramine, octopamine, phenylethanolamine, and tryptamine (Coutts and Baker, 1982). Although GC assays for DA, NA, and 5-HT are available, HPLC analysis with electrochemical detection has for many years now been the method of choice for analysis of these neurotransmitter amines. 

Ribeiro, P. and Webb, R.A. (1983) The occurrence and synthesis of octopamine and other biogenic amines in the cestode Hymenolepis diminuta. Molecular and Biochemical Parasitology 7, 53-62. 

Reserpine. As mentioned earlier, the Rauwolfia alkaloid reserpine is noted for its ability to deplete aromatic biogenic amines in nervous tissue of mammals and insects. One of the more remarkable effects of reserpine in humans is to render individuals indifferent to environmental stimuli. Reserpine appears to have a similar effect on insects, although information is still relatively scanty. In the cockroach, Periplaneta americana, reserpine at 50 vg/g causes strong and long-lasting depletion of the aromatic biogenic amines dopamine, octopamine, and 5-hydroxytryptamine (24). Numerous authors have noted that reserpine has tranquilizing effects on insects, e.g., the ant Formica rufa (30) and . americana (24,31). 

Although these rhythmic contractions of the extensor>tibiae are initiated by spontaneous depolarizations in certain fibers within the muscle, they are regulated by a specific cell on the dorsal surface of the metathoracic ganglion. This cell is found in a cluster of neurosecretory cells called the dorsal unpaired median (DUM) neurons. Neuromuscular transmission and muscular contraction in the extensor-tibiae muscle is modulated by the biogenic amine octopamine and by the peptides, proctolin, and FMRFamide. 

Endogenous biogenic amines in the brain include catecholamines [NE (noradrenaline, NA), dopamine (DA), epinephrine (adrenaline)] 5-HT, histamine, and the so-called trace amines (P-phenylethylamine, tyramine, tryptamine, and octopamine). These amines have in common a arylalkylamine stmcture, and all have been implicated in the etiology of one or more psychiatric disorders and/or in therapeutic and/or adverse effects of drugs used to treat such disorders. In this review on depression, the focus in the case of biogenic amines will be on 5-HT, NE, and DA, although epinephrine and histamine and trace amines have also been implicated (see the section on Other Antidepressant Approaches and Targets ). 

Octopamine, (l-( -hydroxyphenyl)-2-aminoethanol), derives its name from the octopus in whose salivary glands it was first discovered (j.). As a biogenic amine, octopamine remained in relative obscurity until reports of its presence in the nervous tissue of a variety of invertebrates began to be published (2.3). These studies were made possible by the development of a sensitive and specific radioenzymatic assay (4-6). By means of this assay octopamine has now been found to be present in the nervous tissue of all invertebrates examined and, of vital importance, found within... 

Octopamine is one of the most abundant biogenic amines found in the insect nervous system. Its ubiquitous presence in nervous systems coupled to its broad range of actions has led to a rapid accumulation of knowledge about this amine, which is considered to be the insect equivalent of epinephrine and norepinephrine. Octopamine has both central and peripheral actions, where it serves as a... 

The biogenic amine octopamine (OA) is widely recognized as an important neuroregulator in many invertebrates. It has been proposed as a neurotransmitter in the firefly light organ, and as a neuromodulator of muscle action and a neurohormone in the locust (J, 2). Octopamine also appears to act on central nervous system (CNS) sites affecting coordinated motor actions (3,4), and has been shown to modulate CNS thresholds for feeding in blowflies (5), and olfaction in honeybees (6). 

The studies discussed herein show that formamidines without the conventional lethal moiety can elicit dispersal behavior and can interfere with reproduction in twospotted spider mites. Walk-off dispersal elicited by formamidines was correlated with formamidine-induced mortality. Since these structure-activity relationships of formamidines are similar to those for pertubation of octopa-minergic transmission in insects, a similar mechanism could be involved in these actions in mites. Since structure-activity relationships for formamidine effects on spin-down and reproduction were not correlated with those for lethality, other mechanisms, which may or may not involve octopamine or other biogenic amines, are probably associated with these actions. 

The minor biogenic amines such as epinine, octopamine, synephrine, and tyramine represent a tiny fraction of the total in the tissues synthesizing catecholamines under normal circumstances. However, under certain conditions their levels may increase, such as when MAO is inhibited. Some of the ramifications of this will be considered subsequently. 

Octopamine, a < -4 ml nomet by l)-4-hydroxy benz-enemethauol -taminomethyt1-p-hydroxybenzyt alcohol 1-(p-hydroxyphenyl)-2-aminoethanol norsympatol nor-synephrine p- hyd roxypheny let hanolam i ne WV 569. Cs -H N02 mo] wt 153.18. C 62.72%, H 7.24%, N 9.14%, O 20.89%. A biogenic amine that is the phenol analog of noradrenaline (norepinephrine, q.v,). It is a neurosecretory product found in several vertebrates and invertebrates. Formed by f)-hydroxylation of tyramine by the enzyme dopamine 0 -hydroxylase Pisano et a ., Btochlm. Biophys. 

Shimzu et al. investigated biogenic amines in the corpus cardiacum of Periplaneta americana using HPLC with a Neurochem neurochemical analyzer. Dopamine, tyramine, vanilic aid, and octopamine (OA) were detected in the corpus cardiacum. As amino acids, high levels of tyrosine (Tyr-4) and tryptophan were also detected at high levels. Octopamine levels in the corpus cardiacum were increased on injection of an acetone solution. 

This chapter describes the use of this sensitive technique to measure rigorously biogenic amine levels in individually isolated insect identified neurons, and we present data from the locust protocerebral medulla 4 (PM4) neurons as a specific example (5). We also describe the use of GC-MS to monitor the biosynthesis of biogenic amines. The example we present is the synthesis ofp-octopamine, in populations of the dorsal unpaired median (DUM) neurons of the locust, by following the fate of one of its precursors in deuterated form, [ Hs] p-tyramine (4). 

Fig. 1, Confirmation that the cell bodies shown to contain octopamine (in Table 1) belong to PM4 neurons. The photomontage shows the major projections of a Lucifer yellow-stained PM4 neuron revealed by anti-Lucifer yellow immunohistochemistry. The cell body is missing because it was removed for biogenic amine analysis. See Note 9 for additional commentary. Scale 100 pm.

Protocerebral medulla 4 (PM4) neurons are a pair of cells located in the medial deutocerebral region of the locust brain these cells are immunoreactive to octopamine antisera (5). Antigenicity of neurons to antibodies specific to particular biogenic amines is not, by itself, sufficient evidence of transmitter content. More rigorous methods of analysis, e.g., GC-MS, are necessary to identify transmitter content. 

In the transformation of biogenic amines to other biologically active products, a number of different oxygenases, methyltrans-ferases and other enzymes take part (Figure 10.17). Oxidation of tyramine yields 4-(2-amino-l-hydroxyethyl)phenol, known as octopamine, first demonstrated in Octopus species, which acts as a neurohormone and neuromodulator in invertebrates. Methylation... 

A limited number of studies have been performed in which flies will respond to drugs added to food. The agents fed to flies include several biogenic amines such as octopamine (which can restore fertility in females sterile due to a genetic deficiency in octopamine Monastirioti et al. 1996) and those such as tyrosine, tyramine, L-DOPA, and dopamine (C. McClung and J. Hirsh, in prep.) that can affect in vivo responses to aerosolized cocaine and activity levels. In addition, cocaine-HCl can be fed to flies. It does not have same behavioral consequences as exposing flies to aerosolized cocaine-OH, most likely due to the ability of animals to adapt to relatively constant concentrations of cocaine, but can be shown to be effective due to its effects on responsiveness of dopamine receptors (R. Andretic and J. Hirsh, unpubl.). Finally, an inhibitor of tyrosine hydroxylase, 3,5 diio-do-L-tyrosine, can also be fed to flies (Neckameyer 1996). This enzyme performs the... 

Biogenic amines dopamine, serotonin, octopamine, tyramine... 

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