Indoleamines Regulate Vitellogenesis via Cross-Talks With Allatotrophe in the American Cockroach, Periplaneta Americana.

Abstract

Vitellogenesis in many insect species is triggered by juvenile hormone (JH) where other factors such as neural or endocrinological ones also play a important roles. Newly emerged adult females of the American cockroach, Periplaneta americana were injected with indoleamines such as tryptamine (Tn), N-acetyltryptamine (NATn), serotonin (5-HT), N-acetylserotonin (NAS) and melatonin (ME) at 20, 30 and 40 µg in the abdomen. Tn and NATn stimulated Vg synthesis, while 5-HT, NAS and ME inhibited it. These amines may exert the effect on either directly on Vg synthesis in the fat body, Vg receptor, follicle cells, or JH synthesis. We first cloned the genes encoding juvenile hormone acid O-methyltransferase (JHAMT) and farnesoic acid O-methyl transferase (FAMeT) which are involved in JH biosynthesis. qRT-PCR analysis revealed that indoleamines affected the expression of JHAMT and FAMeT in the Br-CA complex. 5-HT, NAS and ME inhibited JHAMT and FAMeT transcription, while Tn and NATn stimulated their transcription. The oocyte length and yolk accumulation showed that, Tn, more likely NATn induced oocyte maturation. Here, the result suggests that intricate mutual interactions induced Vg synthesis in the fat body during oocyte maturation between neurotransmitters/modulator pathway and JH synthesis pathways.

Melatonin in the seasonal response of the aphid Acyrthosiphon pisum

“…Also in A. pernyi, melatonin and serotonin control the photoperiodic response by regulating the release/synthesis of PTTH (Wang et al 2013). In the cockroach Periplaneta americana, melatonin has been shown to inhibit vitellogenin synthesis in the fat body, which is usually associated with ovarian development (Kamruzzaman et al, 2016). Additionally, Kamruzzaman et al (2016) found that melatonin inhibits the expression of the genes JHAMT (Juvenile Hormone Acid O-MethylTransferase) and FAMet (Farnesoic Acid O-Methyltransferase) encoding enzymes involved in the synthesis of Juvenile Hormone (JH).…”

“…In the cockroach Periplaneta americana, melatonin has been shown to inhibit vitellogenin synthesis in the fat body, which is usually associated with ovarian development (Kamruzzaman et al, 2016). Additionally, Kamruzzaman et al (2016) found that melatonin inhibits the expression of the genes JHAMT (Juvenile Hormone Acid O-MethylTransferase) and FAMet (Farnesoic Acid O-Methyltransferase) encoding enzymes involved in the synthesis of Juvenile Hormone (JH). In this context it is worth noticing that JH is known to regulate diapause incidence in several insects (Denlinger et al, 2012;Goodman & Cusson, 2012), in addition to its roles in the regulation of development and the control of polyphenisms.…”

“…In particular, melatonin has been found to participate in the seasonal response in the lepidopteran Antheraea pernyi (Wang et al, 2013;Mohamed et al, 2014). Thus, current evidence suggests a conserved role for melatonin as a hormone of darkness also in insects, although a role as a conveyor of circadian oscillation throughout the organism is not that clear (Gao & Hardie, 1997;Niva & Takeda, 2003;Mohamed et al, 2014;Wang et al, 2015;Kamruzzaman et al, 2016). However, exogenous melatonin has been found to lead to more synchronized locomotor activities in arrhythmic insects (Yamano et al, 2001).…”

Crosstalk among Indoleamines, Neuropeptides and JH/20E in Regulation of Reproduction in the American Cockroach, Periplaneta americana

“…aaNAT transfers an acetyl moiety, a rate-limiting step, to indoleamines and other arylalkylamines including serotonin (5-hydroxytryptamine; 5-HT) to form N-acetylserotonin (NAS; normelatonin), a substrate for MEL synthesis [27]. We have shown that the injections of MEL, 5-HT, NAS, tryptamine (TN) and N-acetyltryptamine (NATN) significantly modified Vg synthesis and affected two JH-synthesizing enzymes, JHAMT and FAMeT [25,26]. aaNAT is highly expressed in the CNS, midgut and reproductive glands in P. americana [25,29].…”

“…The coordination between the reproductive and metabolic organs is vital for survival. Also, the JH/20E route and indoleamine route (see below) have been investigated independently [25,26] and the effects of CCAP/sNPF have been neither investigated directly nor in terms of allatotrophe's regulatory pathway. Disentangling such a complicated network of pathways acting in insect reproduction is important as it is not always clear to what degree functional data obtained in a given model species can be interpolated to other insect taxa because of the different life-history traits, developmental plasticity and the long evolutionary history of many insect orders [4,22].…”