Long-term effects of neonatal cryoanesthesia on hypoxic ventilatory response in weanling rats depend on neonatal testosterone.

Abstract

Among the factors known to interact with the developmental plasticity of the respiratory controller network, gender and perinatal testosterone secretion have recently been described to influence the ventilatory response to acute or chronic hypoxia before puberty (Mortola et al 1996; Joseph et al 1999; Joseph et al 2000). In the present experiments, we used cryoanesthesia as a tool to perform neonatal gonadectomy to address the hypothesis that endogenous neonatal testosterone secretion in male pups could affect the hypoxic ventilatory response (HVR - 10 % O2) in weanling (20-22 day-old) male rats. We selected weaning as an age of fully mature HVR (Joseph et al 2000), while rats are still sexually immature, thus allowing to discard any effect related to endogenous secretion of adult testes (Tatsumi et al. 1994). Our findings show that cryoanesthesia by itself produces a marked decrease of HVR in weanling rats, and this effect was dependent on the neonatal testosterone secretion. Because the cryoanesthesia approach is in many ways similar to surgical processes used for arterial switch operation in human neonates (performed under cardiopulmonary bypass, cardiocirculatory arrest and deep hypothermia), our findings may be potentially relevant for long term outcomes of infants submitted to this surgical procedure.KeywordsCarotid BodyVentilatory ResponseArterial Switch OperationDeep HypothermiaHypoxic Ventilatory ResponseThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.