The chemistry and biochemistry of insect hormones

Abstract

2 Brain Hormone (BH) -4. Function.-Moulting in insects is initiated by neurosecretory cells of the brain which secrete a prothoracotropic hormone. The latter, commonly known as Brain (or Activation) Hormone, stimulates the prothoracic glands to release Moulting Hormone. It has been suggested3 that in addition to its tropic action on the prothoracic gland, BH has a direct action on tissues, acting synergistically with ecdysone. The observation4 that in the cockroach, Periplaneta americana, an elevation of the disaccharide trehalose (the principal circulatory carbohydrate in many insects) is produced by brain extracts (of Periplaneta) takes on new interest following Sacktor's very recent and exciting discovery6 of the presence of the enzyme trehalase in mammalian tissues.Although many other effects have been attributed to BH,2b a complete understanding of its action is still to be developed. B.Chemistry.-In 1962, Kobayashi et aL6 isolated 4 mg. of a crystalline substance by painstakingly dissecting 220,000 'brains' of the silkworm, Bornbyx mori, and apparently demonstrated the hormonal activity of the extract. Subsequent studies7 established unequivocally that the isolated material was cholesterol. That BH is purportedly cholesterol was in direct conflict with other published views. For example, Ischikawa and Ishizaki had previously8 demonstrated that BH (similarly isolated from Bombyx mori) was water (and not ether) soluble. Based on its non-dialysable character, its response to typical protein precipitants, and its deactivation by proteolytic enzymes, it was subsequently concludedD that BH is a protein in nature.Casting doubt on the probability of BH being cholesterol (cholesterol is a normal constituent of the insect diet and would, perhaps, not be expected to exert hormonal effects), Carlisle and Ellislo convincingly demonstrated that pure cholesterol had no effect on moulting in the locust, Locusta migratoria migratorioides; BH does induce moulting in this species.A third view of the chemical nature of BH has been presented by Gersch.1l From both the central nervous system and the cerebrum of the cockroach, Periplaneta americana, Gersch has been able to isolate the neurohormones C1, D1, C2, and D,. Only neurohormone D1, a crystalline peptide, had dernonstrable metamorphosis activity in the Calliphora assay. In his recent review Novak2b agrees that BH is a polypeptide, his support for Gersch's conclusion resting on the observation that known vertebrate-active peptides can affect the insect organism in a way similar to that of the insect neurohormones. In the

Effects of a juvenile hormone analogue on growth and reproduction in the cotton stainer Dysdercus fasciatus Say

“…Hormones are internal secretions that regulate a wide variety of physiological processes especially those concerned with growth, development and egg maturation (Novak, 1966). Similar activity has been reported for a series of compounds related to insect hormones and known as juvenile hormone mimics or analogues (see reviews by Berkoff, 1969;El-Ibrashy, 1970;Ellis et al, 1970;Wigglesworth, 1970). This paper presents the results of a laboratory investigation using one such hormone analogue, methyl farnesoate dihydrochloride (DMF) prepared according to methods described by Law et al (1966) and Romafiuk et al (1967) when applied to the cotton stainer bug Dysdercus fasciatus Say.…”

Insect chemosterilants: a review

“…The induction of biogenic amines as the result of chemosterilant treatment therefore has much wider implications. According to Berkoff (1969), substances such as noradrenaline exert brain hormone-like activity in insects, a property also noted for the juvenile hormone analogues farnesol, farnesyl methyl ether and farnesyl diethylamine. Related substances also caused increased oviposition in Dysdercus (Carlisle & Ellis, 1967).…”

Chemistry of Natural Products Derived from Marine Sources

“…The chemistry and biochemistry of moulting hormones has been reviewed by BERKOFF (46) and that of arthropod moulting hormones by HrKINO …”