Fig. 2.

The Karolinska Institutet experimental model of perinatal asphyxia. The experiment starts by an evaluation of the oestral cycle of young female Wistar rats (~2 months of age), in order to plan for a programmed mating. The female is exposed to a male at the time of the pro-oestrous for one night and thereafter the presence of a vaginal clot is evaluated. Pregnancy is continuously monitored until delivery of a first pup is observed (representing a vaginally delivered control), or when the maturity of the foetuses is assessed by clinical abdominal palpation, indicating that the dam is ready for delivery (~22 days after the identification of a vaginal clot). The animal is anaesthetised, killed by neck dislocation and subjected to a caesarean section and hysterectomy. The uterine horns are then immersed into a temperature-controlled water bath (37°C) for various periods of time. One or two pups are immediately delivered after hysterectomy, representing a caesarean-delivered control. After asphyxia, the pups are removed from the uterine horns and resuscitated by cleaning the faces of the animals from fluid and amniotic tissue, freeing the mouth and the nose, and stimulated to pulmonary breathing. Pulmonary breathing is further monitored and the surviving pups are evaluated by an Apgar scale 40–60 min after delivery. Thereafter the pups are given to surrogate dams for nursing (delivering immediately before the hysterectomised dam), pending further experiments (see Dell’Anna et al. 1997; Klawitter et al. 2007)