Caffeine is the methylxantine currently prescribed for the management of neonate apnoea to regularize breath. Using an animal model to mimic this clinical exposure to caffeine (Guillet and Kellog, 1990), we investigated its effects on the ontogeny of the adenosine A1 receptor respiratory network (Gaytan et al., 2006), demonstrating an increase of this receptor labelling mainly at the parabrachial medial and Kölliker-Fuse nuclei and ventrolateral medulla. The aim of the present report was to map c-Fos expression to identify regions affected by adenosinergic A1 stimulation. Following birth, the pups were fed by gavages on days 2-6 of life, one group receiving therapeutic doses of caffeine plus glucose and the other water plus glucose (vehicle), in a volume of 0.05 ml/10 g body weight. The Animal Ethics Committee approved the experimental protocol (86/609/EEC). The animals were sacrificed from postnatal days P2 to P8. To visualize c-Fos positive neurons the series was processed by an immunohistochemical protocol with a rabbit anti-Fos polyclonal antibody (1:3000, sc52 Santacruz) and a secondary biotin-conjugated-SP (1:1000, IgG(H+L) 211-065-109, Jackson Immuno Research).

The main difference of the pattern of c-Fos positive neurons distribution between the two groups was found at the end of the treatment (P6), where the caffeinated group presented a higher density of positive neurons within the parabrachial and raphe nuclei and the nucleus of the tractus solitarius, which are known for its role on respiratory function. Identification of specific activation of parabrachial medial nucleus at P6 emphasizes its role in respiratory rhythm postnatal development. PAI-CVI-183.