Ventilatory stimulation by dopamine-receptor antagonists in the mouse

Area of Science:

• Neuroscience
• Respiratory Physiology
• Pharmacology

Background:

• Dopaminergic mechanisms are implicated in the control of breathing.
• Neuroleptic drugs, known for dopamine receptor antagonism, can influence physiological functions.

Purpose of the Study:

• To investigate the role of dopaminergic mechanisms in modulating ventilatory control in awake mice.
• To determine the relationship between neuroleptic drug properties and their effects on breathing.

Main Methods:

• Ventilation was measured using plethysmography in awake mice.
• Mice received intraperitoneal injections of neuroleptic drugs (haloperidol, droperidol, prochlorperazine, chlorpromazine).
• Effects on ventilation were assessed at rest, during hypoxia, and hypercapnia; carotid body resection was performed in some animals.

Main Results:

• Neuroleptic drugs dose-dependently augmented resting and hypoxic ventilation, while reducing hypercapnic ventilation.
• The augmentation of hypoxic ventilation correlated linearly with the drugs' in vitro affinity for dopamine receptors.
• Differences in drug efficacy were linked to their affinities for alpha-adrenoceptors; combined blockade with phentolamine enhanced effects.

Conclusions:

• Dopaminergic mechanisms within the carotid body play a significant role in modulating ventilatory control in awake mice.
• Neuroleptic drugs that block both dopamine and alpha-adrenoceptors are most effective in augmenting hypoxic ventilation.