Neurohormones of invertebrates

Hormones of insects and crustaceans. Peptide neurohormones of insect brains348 include the pentapeptide proctolin (Table 30-5), which was first iso-lated from the cockroach and has since been found in crustaceans and in mammalian brain. It has been traced to specific insect neurons.349 A nonapeptide neurohormone from the shore crab does not resemble any other known vertebrate or invertebrate hormone.350... 

Neuroendocrine control of invertebrate development was first demonstrated by Kopec CL2) with neck ligation and brain extirpation-reimplantation studies using the gypsy moth, Lymantria dispar (Lepidoptera Lymantriidae). His demonstration of a "pupation factor", origmating in the bi in, provided the impetus for identification of numerous invertebrate physiological processes controlled by peptide neurohormones (3.41 In insects, identified processes now number over thirty (5). Knowledge of these processes has provided for the development of bioassays used in the isolation of neuropeptides. Since 1975, over fo insect peptide neurohormones have been isolated and sequenced (5-81... 

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). 

Prostaglandins are cyclopentane derivatives (Section 1.4) formed from poljomsaturated fatty acids by most mammalian tissues (and by tissues of lower vertebrates and certain invertebrates). These prostaglandins modulate a host of hormonal, neurohormonal and other stimuli and have a variety of other pharmacological actions (Samuelsson et aL, 1975, 1978). Thromboxanes themselves are of pronounced biological activity but are unstable with short half-lives (cf. Samuelsson etal., 1978). 

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... 

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