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Influence of hormones and undernutrition on brain development in newborn rats
Insights
Early life exposure to high doses of L-thyroxine (T4) and cortisol in rats alters brain development and energy metabolism. These effects mirror those seen in prenatal undernourishment, suggesting hypothalamic-pituitary disruption.
Area of Science:
- Endocrinology
- Developmental Biology
- Neuroscience
Background:
- Hormonal influences during early development are critical for growth and metabolic regulation.
- Prenatal undernourishment can lead to long-term physiological deficits.
- The hypothalamic-pituitary axis plays a central role in mediating stress and metabolic responses.
Purpose of the Study:
- To investigate the effects of early-life L-thyroxine (T4) and cortisol administration on rat development.
- To compare the outcomes of hormonal treatment with those of prenatal undernourishment.
- To explore potential alterations in the hypothalamic-pituitary complex.
Main Methods:
- Rats were administered high doses of L-thyroxine (T4) or cortisol during specific early postnatal periods.
- Body weight, brain weight, and brain energy substrates (glucose, ketone bodies) were measured.
- Pituitary hormones (GH, TSH) and plasma ACTH levels were assessed.
- Comparisons were made with a cohort of prenatally undernourished rats.
Main Results:
- T4 and cortisol treatments decreased body and brain weight, and perturbed brain energy substrates.
- Hormonal treatments led to decreased pituitary GH and TSH.
- Cortisol treatment reduced plasma ACTH levels.
- Undernourished rats exhibited reduced pituitary TSH content.
Conclusions:
- Early-life administration of T4 and cortisol induces developmental and metabolic disturbances similar to prenatal undernourishment.
- These findings suggest a shared mechanism of hypothalamic-pituitary complex alteration across the experimental models.
- The study highlights the sensitivity of early development to hormonal and nutritional insults.
Abstract:
High L-thyroxine (T4) and cortisol doses given to rats during the first 8 days of life and on the first day only respectively, produce decrease of body and brain weight and perturbances to brain energy substrates, i.e. glucose and ketone bodies. The same alterations are found in the undernourished rats from the prenatal period. The pituitary GH and TSH is decreased in the T4- and cortisol-injected animals. The plasma ACTH is decreased in the treated cortisol animals at 8, 12 and 22 days of life. The pituitary TSH content is reduced with respect to controls in the undernourished animals from 14 to 70 days of life. From the exposed experiments we suggest an alteration in the hypothalamic-pituitary complex in T4- and cortisol-treated rats, and describe the similarities between the three experimental models.