An article detailing the effect of acute sucrose and water deprivation on the physiology of the mosquito heart was published today in Journal of Insect Physiology.

The insect heart is myogenic, but several neuropeptides and neurotransmitters modulate heart rhythmicity and directionality.  The circumstances that lead to changes in the endogenous production of cardiomyotropic or cardioinhibitory factors remain largely unknown.  However, several environmental and physiological conditions are known to affect heart physiology.

In the present study we tested the effect of acute deprivation of sucrose and water on the heart of the malaria mosquito, Anopheles gambiae.  By measuring heart physiology and nutritional status in the adult stage we show that sucrose deprivation for 24 h has little effect on heart physiology but that the combination of sucrose and water deprivation for the same period results in a reduction in the heart contraction rate.  Neither sucrose nor water deprivation induces significant changes in the expression of myotropic neuropeptides but the combination of sucrose and water deprivation leads to elevated transcription of nitric oxide synthase.  The highlights of this paper are:

1. 1.Deprivation of sucrose for 24 h does not affect the mosquito heart rate.
   

2. 2.Deprivation of both sucrose and water suppresses the mosquito heart rate.
   

3. 3.Deprivation of both sucrose and water decreases mosquito weight and abdominal width.
   

4. 4.Deprivation of both sucrose and water does not alter the transcription of five cardiomyotropic neuropeptides.
   

5. 5.Deprivation of both sucrose and water increases the transcription of nitric oxide synthase.
   

Article citation:

Ellison, H.E., T.Y. Estévez-Lao, C.S. Murphree, and J.F. Hillyer. 2015. Deprivation of both sucrose and water reduces the mosquito heart contraction rate while increasing the expression of nitric oxide synthase. Journal of Insect Physiology. 74:1-9.

(PubMed) (See it in JIP) (Email me for a pdf copy)

Graphical abstract:

Article abstract:

Adult female mosquitoes rely on carbohydrate-rich plant nectars as their main source of energy. In the present study we tested whether the deprivation of a carbohydrate dietary source or the deprivation of both carbohydrate and water affects mosquito heart physiology. Intravital video imaging of Anopheles gambiae showed that, relative to sucrose fed mosquitoes, the deprivation of both sucrose and water for 24 h, but not the deprivation of sucrose alone, reduces the heart contraction rate. Measurement of the protein, carbohydrate and lipid content of mosquitoes in the three treatment groups did not explain this cardiac phenotype. However, while the deprivation of sucrose reduced mosquito weight and abdominal width, the deprivation of both sucrose and water reduced mosquito weight even further without augmenting the change in abdominal width, indirectly suggesting that starvation and dehydration reduces hemolymph pressure. Analysis of the mRNA levels of crustacean cardioactive peptide (CCAP), FMRFamide, corazonin, neuropeptide F and short neuropeptide F then suggested that these neuropeptides do not regulate the cardiac phenotype observed. However, relative to sucrose fed and sucrose deprived mosquitoes, the mRNA level of nitric oxide synthase (NOS) was significantly elevated in mosquitoes that had been deprived of both sucrose and water. Given that nitric oxide suppresses the heart rate of vertebrates and invertebrates, these data suggest a role for this free radical in modulating mosquito heart physiology.