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Updated: May 23, 2026
Neurodevelopmental Reflex Testing in Neonatal Rat Pups
Published on: April 24, 2017
Cardiac responses of rats submitted to postnatal protein restriction
Tatiane Moisés Murça1, Tatiana Soares Dos Reis Magno, Marilda Luz de Andrade De Maria
1Universidade Federal de Minas Gerais, Belo Horizonte 31.270-901, MG, Brazil.
Insights
Postnatal protein restriction in rats leads to an overworking heart with impaired diastolic function and cardiac hypertrophy. This is partly due to increased sympathetic nerve fibers in the heart.
Area of Science:
- Cardiovascular Physiology
- Developmental Nutrition
- Cardiac Adaptation
Background:
- Childhood undernutrition significantly impacts cardiovascular homeostasis.
- Protein restriction during development can have lasting effects on heart function.
Purpose of the Study:
- To investigate the cardiac function in rats subjected to postnatal protein restriction.
- To evaluate the impact of protein deficiency on cardiac structure and autonomic innervation.
Main Methods:
- Male Wistar rats were fed low-protein (6%) or regular (20%) diets for 5 weeks.
- Cardiac function assessed via echocardiography and isolated heart techniques.
- Cardiac noradrenergic fiber density and hematological profiles were analyzed.
Main Results:
- Malnourished rats showed elevated blood pressure, cardiac hypertrophy, and impaired diastolic function.
- Increased fractional shortening and systolic tension indicated an overworking heart.
- Elevated cardiac noradrenergic fiber density was observed in malnourished rats.
Conclusions:
- Postnatal protein restriction induces cardiac adaptation, leading to an early overworking heart.
- Increased sympathetic innervation plays a role in these cardiac changes.
- Findings offer insights for managing undernutrition's cardiovascular consequences.
Abstract:
Undernutrition during critical stages of development and childhood has important effects on cardiovascular homeostasis. The present study was undertaken to evaluate the in vivo and ex vivo cardiac function of rats submitted to postnatal protein restriction. Male Wistar rats (28 days old) were fed a regular (20%) or low-protein (6%) diet over 5 weeks. After this period, cardiac function was analyzed by echocardiography and isolated heart preparation. Furthermore, the density of cardiac noradrenergic fibers and hematological profile were evaluated. We found that malnourished rats exhibited elevated arterial blood pressure, increased fractional shortening (echocardiography), increased systolic tension, increased ±dT/dt (isolated heart technique), impaired diastolic function characterized by a slight increase in the left ventricular end-diastolic diameter (echocardiography) and decreased diastolic tension (isolated heart technique), and cardiac hypertrophy evidenced by augmentation of the posterior left ventricular wall and discrete hematological changes. In addition, malnourished rats exhibited increased noradrenergic fiber density in their hearts (0.08% ± 0.02% area in control rats vs. 0.17% ± 0.03% area in malnourished rats). Our current data demonstrate that postnatal protein restriction causes cardiac adaptation characterized by an early overworking heart. This is at least in part mediated by an increase in the efferent sympathetic fibers to the heart. These findings provide important information for efforts to prevent and manage the consequences of undernutrition in the human population.
