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Peripheral administration of alpha-MSH reduces fever in older and younger rabbits
Abstract:
In these experiments IV, ICV and intra-gastric administration of alpha-MSH reduced fever caused by injections of leukocytic pyrogen (LP). 2.5 micrograms alpha-MSH injected IV reduced fever caused by IV LP, more so in rabbits over 3 yrs old than in those under 2 yrs of age; 5 mg of acetaminophen given IV had no antipyretic effect in either age group. ICV administration of 25 ng alpha-MSH reduced fever caused by IV LP injection in the older but not in the younger rabbits, alpha-MSH given IV (2.5 micrograms) also lowered fever induced by ICV injection of LP in older but not in younger animals. Both older and younger rabbits showed reductions in fever evoked by IV LP after 2.5 mg alpha-MSH was given by gastric tube. The results indicate that this peptide which occurs naturally within the brain has potent antipyretic properties when given systemically, presumably as a result of a central antipyretic action. Greater sensitivity to central alpha-MSH in the older rabbits may account for the reduced febrile response seen in the aged. The findings support previous data which suggest that central alpha-MSH has a physiological role in the limitation of fever.
Insights
Alpha-melanocyte-stimulating hormone (alpha-MSH) effectively reduces fever in rabbits, acting centrally. Older rabbits showed greater sensitivity to alpha-MSH
Area of Science:
- Neuroscience
- Pharmacology
- Immunology
Background:
- Fever is a common physiological response to infection and inflammation.
- Alpha-melanocyte-stimulating hormone (alpha-MSH) is a peptide hormone found in the brain with potential regulatory functions.
- Understanding the mechanisms of fever and its modulation is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the antipyretic effects of alpha-MSH administered via different routes (intravenous, intracerebroventricular, intra-gastric).
- To compare the efficacy of alpha-MSH with acetaminophen in reducing fever.
- To explore age-related differences in response to alpha-MSH.
Main Methods:
- Rabbits of different age groups were injected with leukocytic pyrogen (LP) to induce fever.
- Alpha-MSH was administered intravenously (IV), intracerebroventricularly (ICV), or intra-gastrically.
- Acetaminophen was administered IV as a control.
- Fever reduction was measured and compared across different administration routes and age groups.
Main Results:
- IV, ICV, and intra-gastric administration of alpha-MSH significantly reduced LP-induced fever in rabbits.
- Older rabbits (over 3 years) exhibited a more pronounced reduction in fever compared to younger rabbits (under 2 years) with alpha-MSH treatment.
- IV acetaminophen (5 mg) showed no significant antipyretic effect in either age group.
- Central alpha-MSH administration was effective in older rabbits but not younger ones, suggesting age-dependent central sensitivity.
Conclusions:
- Alpha-MSH possesses potent antipyretic properties, likely acting centrally.
- The findings suggest a physiological role for endogenous alpha-MSH in fever limitation.
- Age-related differences in sensitivity to central alpha-MSH may contribute to variations in febrile responses in aged individuals.