Rhodnius prolixus Malpighian tubules and control of diuresis by neurohormones

Abstract

Rhodnius prolixus Malpighian tubules (MTs) are a good model for fluid and ion secretion studies in view of the dramatic postprandial diuresis, which follows its massive blood meals. Ingestion of a blood meal equals to 10-12 times their initial body mass, leads to rapid activation of high output by excretory system, which eliminates 40-50% of the fluid mass. Secretion of ions and water is stimulated 1000-fold by serotonin and diuretic hormone. These hormones cooperate synergistically to activate adenylate cyclase activity from MTs cells, which increase the level of intracellular cAMP. The anti-diuretic hormones have also an important role in the fluid maintenance of Rhodnius prolixus. Several hours after insect feeding occurs a reduction in urine flow, that has been thought to result from a decreased diuretic hormone release or from a novel mechanism of anti-diuresis involving insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP. In this article it is discussed how the hormone regulation of fluid transport is done in Rhodnius prolixus MTs.

Fine structure of the Malpighian tubules in Gryllus campestris(Linnaeus, 1758) (Orthoptera, Gryllidae)

“…Contraction of the muscles creates hydrostatic pressure across the Malpighian tubule system for the movement of water (Denholm and Skaer, 2005;Chapman, 2013). Therefore, in G. campestris, the outer surface of the Malpighian tubules is surrounded by muscle as in other species previously examined (Beams et al, 1955;Ramsay, 1955;Arab and Caetano, 2002;Martini et al, 2007).…”

Malpighian Tubules in Larvae of Diatraea saccharalis (Lepidoptera; Crambidae): A Morphological Comparison between Non-Parasitized and Parasitized by Cotesia flavipes (Hymenoptera; Braconidae)

“…Mitochondria can also be found within the microvilli. This characteristic of the primary or secretory cells has been described for various insect orders, including Coleoptera [31], Díptera [32] [33], Hemiptera [34] and Hymenoptera [6].…”

SIFamide Influences Feeding in the Chagas Disease Vector, Rhodnius prolixus

“…Triatomines, such as R. prolixus, are hemimetablous insects and all post-embryonic stages consume a blood meal that in fifth instars may be equivalent to up to 10 times their unfed body weight. The five instar stages require this blood meal to trigger growth and development into the next instar or adult (Martini et al, 2007). Adults acquire energy from the blood meal to fuel other energy consuming behaviors such as mating and egg laying.…”

“…Adults acquire energy from the blood meal to fuel other energy consuming behaviors such as mating and egg laying. Immediately after ingestion of a blood meal, R. prolixus triggers diuresis (excretion of urine) and associated downstream physiological events to remove excess water and salt (Orchard, 2006(Orchard, , 2009Martini et al, 2007). During diuresis, R. prolixus transmits the protozoan parasite Trypanosoma cruzi, the disease-causing agent of Chagas disease, to a human host.…”