Sex-specific response to hypoxia in a reduced brainstem preparation from Xenopus laevis

• We examined the sex-specific response to acute hypoxia from adult Xenopus laevis.
• Experiments were performed on in vitro reduced brainstem preparations from adults.
• There is a sexual dimorphism in the burst frequency increase at the onset of hypoxia.
• In frogs, the respiratory network of females tolerates hypoxia better than males.

Respiratory reflexes and tolerance to hypoxia show significant sexual dimorphism. However, the data supporting this notion originates exclusively from mammals. To determine whether this concept is limited to this group of vertebrates, we examined the sex-specific response to acute hypoxia in an adult reduced brainstem preparation from Xenopus laevis. Within the first 5 min of exposure to hypoxic aCSF (98% N2/2% CO2), recordings of respiratory-related activity show a stronger increase in fictive breathing frequency in males than females. This initial response was followed by a decrease in respiratory-related activity; this depression occurred 6 min sooner in males than females. These results represent new evidences of sexual dimorphism in respiratory control in amphibians and provide potential insight in understanding the homology with other groups of vertebrates, including mammals.