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Food intake of infant rats after intraperitoneal administration of insulin
Insights
Intraperitoneal insulin reduced milk intake in young infant rats but increased food intake in 28-day-old pups. This age-dependent effect is linked to transient hypoglycemia following insulin administration.
Area of Science:
- Endocrinology
- Developmental Biology
- Neuroscience
Background:
- Insulin plays a crucial role in metabolic regulation, including appetite control.
- The impact of insulin administration routes on food intake during early development is not fully understood.
Purpose of the Study:
- To investigate the effects of intraperitoneal (IP) insulin on food intake in infant rats at different developmental stages.
- To compare the effects of IP versus subcutaneous (SC) insulin administration on blood glucose levels and subsequent food intake.
Main Methods:
- Infant rats of varying ages (5, 9, 13, 17, 24, and 28 days old) received IP insulin injections.
- Milk intake and general food intake were measured at different time points post-injection.
- Blood glucose levels were monitored after SC and IP insulin administration in 24-day-old pups.
Main Results:
- IP insulin significantly reduced milk intake in 13 and 17-day-old pups.
- No significant changes in food intake were observed in 5, 9, and 24-day-old pups after IP insulin.
- IP insulin increased food intake only in 28-day-old pups.
- SC insulin administration led to short-term hyperphagia in 24-day-old pups.
- Blood glucose levels were lower 3 hours after SC insulin compared to IP insulin.
Conclusions:
- IP insulin administration exhibits age-dependent effects on food intake in developing rats.
- The observed increase in food intake with IP insulin occurs only after the 28th day of life, coinciding with a short-lasting hypoglycemia.
- Route of insulin administration influences both blood glucose levels and feeding responses in infant rats.
Abstract:
The effects of intraperitoneal insulin on the food intake have been determined in infant rats up to weaning. It was found that intraperitoneal (IP) insulin reduced the milk intake of 13 and 17 day-old pups for three hours after treatment. In 5, 9 and 24 day-old pups the food intake was not significantly changed after IP insulin administration. Only in 28 day-old rat pups IP insulin induced an increase of food intake. Since subcutaneously (SC) administered insulin gave rise to short-term hyperphagia in 24 day-old rat pups we assessed the effects of SC versus IP insulin on the blood glucose level. Blood glucose was lower 3 hours after SC administration compared to the IP route. Results indicate that IP insulin causes a short lasting hypoglycaemia and consequently IP insulin increases food intake only after the 28th day of life.