Central histamine contributed to temperature-induced polypnea in mice

Area of Science:

• Physiology
• Neuroscience
• Respiratory Regulation

Background:

• Body temperature significantly influences breathing patterns.
• The central mechanisms regulating these temperature-induced breathing changes remain largely unknown.
• Central histamine's role in thermoregulation is established, but its impact on breathing patterns requires further investigation.

Purpose of the Study:

• To investigate the effect of elevated body temperature on breathing patterns in conscious mice.
• To determine the role of central histamine in mediating temperature-dependent alterations in breathing patterns.

Main Methods:

• Conscious mice were subjected to increasing hypercapnia at normal and raised body temperatures.
• Central histamine depletion was achieved using S(+)-alpha-fluoromethylhistidine hydrochloride (alpha-FMH), a histidine decarboxylase inhibitor.
• Breathing patterns, including respiratory frequency, inspiratory time, expiratory time, and tidal volume, were analyzed.

Main Results:

• Elevated body temperature increased respiratory frequency, shortened inspiratory and expiratory times, and decreased tidal volume.
• Histamine depletion with alpha-FMH at raised body temperatures resulted in decreased respiratory frequency and prolonged expiratory time.
• These effects of histamine depletion on breathing patterns were not observed at normal body temperatures.

Conclusions:

• Central histamine plays a crucial role in increasing respiratory frequency during hyperthermia.
• Histamine contributes to the shortening of expiratory time as a mechanism for adapting breathing patterns to elevated body temperatures.
• These findings elucidate a novel central pathway linking body temperature and respiratory control.