Effects of melatonin on the passive mechanical response of arteries in chronic hypoxic newborn lambs

Rivera, Eugenio; García‐Herrera, Claudio; Gonzaléz‐Candia, Alejandro; Celentano, Diego J.; Herrera, Emílio

doi:10.1016/j.jmbbm.2020.104013

Cited by 10 publications

(37 citation statements)

References 47 publications

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“…The tissue studied in this work corresponded to thoracic aortas (TA) of 9 newborns lambs gestated at high altitude (Putre, Chile, 3600 masl). In this altitude level, the animals developed PAHN due to their gestation and birth under chronic hypobaric hypoxia 2 , 3 , 5 , 6 .…”

Section: Methodsmentioning

confidence: 99%

“…However, it is insufficient to achieve a robust mechanical characterization, since it does not allow to replicate the complex loading conditions present in a physiological state 37 , 38 . Its main result is the stress-stretch relation under uniform deformation and it provides a set of parameters that have been used to compare the mechanical responses on soft tisues 2 , 16 , 39 , 40 .…”

Section: Methodsmentioning

confidence: 99%

“…During the last years, several studies highlighted the potential benefits of postnatal treatment with melatonin to cope PAHN, showing that it has effective antioxidant, vasodilator, antiremodeling and antihipertensive effects at the pulmonary level 3 , 5 , 6 , 9 , 10 . Although melatonin decreased large arteries thicknesses, such as the main pulmonary and aorta arteries, no biomechanical changes has been observed 2 . However, few is known still about the biomechanical changes that take place on the major arteries of the circulatory system due to melatonin administration 2 .…”

Section: Introductionmentioning

confidence: 93%

“…Although melatonin decreased large arteries thicknesses, such as the main pulmonary and aorta arteries, no biomechanical changes has been observed 2 . However, few is known still about the biomechanical changes that take place on the major arteries of the circulatory system due to melatonin administration 2 .…”

Section: Introductionmentioning

confidence: 93%

“…Pregnancy and birth under hypobaric hypoxia as seen in high-altitude populations increase fetal and neonatal complications 1 , 2 . The most common cardiovascular complications are pulmonary arterial hypertension of the newborns (PAHN) and right ventricular remodelling.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Biomechanical characterization of the passive response of the thoracic aorta in chronic hypoxic newborn lambs using an evolutionary strategy

Rivera

Canales

Pacheco

et al. 2021

Sci Rep

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The present study involves experiments and modelling aimed at characterizing the passive structural mechanical behavior of the chronic hypoxic lamb thoracic aorta, whose gestation, birth and postnatal period were carried at high altitude (3600 masl). To this end, the mechanical response was studied via tensile and pressurization tests. The tensile and pressurization tests measurements were used simultaneously to calibrate the material parameters of the Gasser–Holzapfel–Ogden (GHO) hyperelasctic anisotropic constitutive model through an analytical-numerical optimization procedure solved with an evolutionary strategy that guarantees a stable response of the model. The model and procedure of calibration adequately adjust to the material behavior in a wide deformation range with an appropriate physical description. The results of this study predict the mechanical response of the lamb thoracic aorta under generalized loading states like those that can occur in physiological conditions and/or in systemic arterial hypertension. Finally, the novel use of the evolutionary strategy, together with the set of experiments and tools used in this study, provide a robust alternative to validate biomechanical characterizations.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Biomechanical characterization of the passive response of the thoracic aorta in chronic hypoxic newborn lambs using an evolutionary strategy

Rivera

Canales

Pacheco

et al. 2021

Sci Rep

Self Cite

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Implanting melatonin at lambing enhances lamb growth and maintains high fat content in milk

2021

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Background: Recent studies have shown that melatonin implants administered during pregnancy reduced neonatal lamb mortality and produced high survival rates at weaning. This study was designed to quantify the effects of melatonin implantation of ewes and lambs immediately after lambing on the growth of lambs and the quality of milk throughout lactation.Results: In experiment 1, treatment with melatonin the lambs did not have a signi cant effect on liveweight (LW) (±S.E.M.) at weaning or average daily gain (ADG) until weaning. These results were similar in experiment 2, although lambs reared by melatonin-implanted ewes presented signi cantly (P<0.05) higher LW at weaning and ADG than did lambs from control ewes. The effect of melatonin implantation of the mothers was particularly evident in male lambs, so that male lambs reared by treated ewes presented signi cantly higher LW at week 2, 3, and 4 than did male lambs reared by control ewes.The fat content of milk was signi cantly (P<0.05) higher in implanted ewes than it was in control ewes at day 45 of lactation. Protein and lactose content of milk did not differ signi cantly between groups. In experiment 3, using arti cially-reared lambs, melatonin treatment of the lambs at birth did not have a signi cant effect on LW at weaning, or ADG.Conclusions: Melatonin treatment of ewes at lambing induced a high growth rate of their lambs and increased the fat content of the milk; however, the direct treatment with melatonin of the lambs at birth did not have an effect in their growth rate.

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Biomechanical and structural responses of the aorta to intermittent hypobaric hypoxia in a rat model

Utrera

Navarrete

Gonzaléz‐Candia

et al. 2022

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High altitude hypoxia is a condition experienced by diverse populations worldwide. In addition, several jobs require working shifts where workers are exposed to repetitive cycles of hypobaric hypoxia and normobaric normoxia. Currently, few is known about the biomechanical cardiovascular responses of this condition. In the present study, we investigate the cycle-dependent biomechanical effects of intermittent hypobaric hypoxia (IHH) on the thoracic aorta artery, in terms of both structure and function. To determine the vascular effects of IHH, functional, mechanical and histological approaches were carried out in the thoracic aorta artery, using uniaxial, pre-stretch, ring opening, myography, and histological tests. Three groups of rats were established: control (normobaric normoxia, NN), 4-cycles of intermittent hypoxia (short-term intermittent hypobaric hypoxia, STH), and 10-cycles of intermittent hypoxia (long-term intermittent hypobaric hypoxia, LTH). The pre-stretch and ring opening tests, aimed at quantifying residual strains of the tissues in longitudinal and circumferential directions, showed that the hypoxia condition leads to an increase in the longitudinal stretch and a marked decrease of the circumferential residual strain. The uniaxial mechanical tests were used to determine the elastic properties of the tissues, showing that a general stiffening process occurs during the early stages of the IH (STH group), specially leading to a significative increase in the high strain elastic modulus ($$E_{2}$$ E 2 ) and an increasing trend of low strain elastic modulus ($$E_{1}$$ E 1 ). In contrast, the LTH group showed a more control-like mechanical behavior. Myography test, used to assess the vasoactive function, revealed that IH induces a high sensitivity to vasoconstrictor agents as a function of hypoxic cycles. In addition, the aorta showed an increased muscle-dependent vasorelaxation on the LTH group. Histological tests, used to quantify the elastic fiber, nuclei, and geometrical properties, showed that the STH group presents a state of vascular fibrosis, with a significant increase in elastin content, and a tendency towards an increase in collagen fibers. In addition, advanced stages of IH (LTH), showed a vascular remodeling effect with a significant increase of internal and external diameters. Considering all the multidimensional vascular effects, we propose the existence of a long-term passive adaptation mechanism and vascular dysfunction as cycle-dependent effects of intermittent exposures to hypobaric hypoxia.

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Effects of melatonin on the passive mechanical response of arteries in chronic hypoxic newborn lambs

Cited by 10 publications

References 47 publications

Biomechanical characterization of the passive response of the thoracic aorta in chronic hypoxic newborn lambs using an evolutionary strategy

Biomechanical characterization of the passive response of the thoracic aorta in chronic hypoxic newborn lambs using an evolutionary strategy

Implanting melatonin at lambing enhances lamb growth and maintains high fat content in milk

Biomechanical and structural responses of the aorta to intermittent hypobaric hypoxia in a rat model

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