Heart mechanical and hemodynamic parameters of a beetle, Tenebrio molitor, at selected ages

Abstract

The physiological processes that occur during the aging of insects are poorly understood. The aim of this study was to describe the changes in contractile activity and hemodynamic parameters of the heart that take place as the coleopteran beetle, Tenebrio molitor, ages. The frequency of heart contractions in beetles that had just undergone metamorphosis (median 24.7 beats/min) was significantly lower than the frequency of heart contractions in older beetles. In 56% of beetles that were < 1 week of age, a pattern of contractile activity with alternating periods of higher and lower contraction frequency was detected, suggesting that some posteclosion developmental processes occur during the first week of adulthood. All beetles that were 1 week of age showed a regular rhythm of heart contractions (median 72 beats/min). In older beetles, abnormalities such as heart arrhythmias or heart arrest were observed. The incidence of arrhythmia as well as the arrhythmicity index was highest in beetles that were 8-18 weeks old. The calculated stroke volume (SV) was also found to increase from eclosion to 12 weeks of age, and then decreased as adults aged further. Interestingly, cardiac output increased gradually, but the ejection fraction did not change significantly with age.

Beetles as Model Organisms in Physiological, Biomedical and Environmental Studies – A Review

“…It has also been demonstrated that the majority of older wild-type flies exhibit non-rhythmic heart contraction patterns, including frequent asystole/bradycardia and ectopic beats (Ocorr et al, 2007b; Santalla et al, 2014). Similar changes in the heart rhythm have been detected in T. molitor beetles (Pacholska-Bogalska et al, 2018). In older beetles, more abnormalities in heart rhythm, arrhythmias, were detected.…”

“…In older beetles, more abnormalities in heart rhythm, arrhythmias, were detected. In this group of beetles, the incidence of arrhythmia and the arrhythmicity index were higher than in a group of younger beetles (Pacholska-Bogalska et al, 2018). This finding suggests that the beetle heart preparations can also be used as a model in the studies on aging and for testing cardioactive drugs as well.…”

“…Therefore, it is important to gain extensive knowledge about the mechanisms that cause certain diseases or, on the other hand, find various substances that modify the activity of the heart to create a solid basis for further progress in the treatment of CVDs. Research on various insect models, including beetles, are very promising in this field (Szymczak et al, 2014; Zhu et al, 2017; Pacholska-Bogalska et al, 2018). The heart/myocardium of insects has been shown to be a convenient biomedical model.…”

Differentiated Effects of Secondary Metabolites from Solanaceae and Brassicaceae Plant Families on the Heartbeat of Tenebrio molitor Pupae

“…Functional analogies at the molecular and cellular level between the myocardium of the insect and the mammalian heart were shown in the research on the fruit fly D. melanogaster , among others, by Bier and Bodmer [13] and Ocorr et al [14]. Nowadays, other insects, such as locusts ( L. migratoria ), stick insects ( B. extradentatum ), moths ( B. mori) or beetles ( T. molitor ) are used more and more often to evaluate the action of various bioactive substances, as well as to analyse the basis and the course of some diseases [15,16,17].…”

Probability that there is a mammalian counterpart of cardiac clock in insects

“…The HR of T. molitor is often studied. Also arrhythmicity is present in beetles already at first week of life and its index during aging increases to 3.2 versus 0.2 (Pacholska‐Bogalska et al, 2018). An increase in diastolic intervals may accompany this development.…”