[Circadian variations in the incorporation of gamma-aminobutyric acid (GABA) and tritiated taurine into the pineal body of CD mice]. / Variations nycthémérales de l'incorporation de l'acide gamma-aminobutyrique (GABA) et de la taurine tritiés par l'épiphyse de la souris CD.

Pineal uptake of two putative neurotransmitters, gamma-aminobutyric acid (GABA) and taurine, was investigated during the 24 h-cycle in mice kept in long (14L/10D) or short (10L/14D) photoperiods. Tritiated mediators were intraperitoneally injected and their concentration both in pineal gland and cerebellum were measured at several times along the nycthemere. A circadian rhythm of exogenous GABA uptake was observed in mice kept in long photoperiods: GABA uptake was high during the night, when the gland was active and low during the day. It corresponded to the pineal cycle of indoleamine synthesis. It was particularly sensitive to sudden changes of lighting. In short photoperiods, a similar cycle was observed but the result was not significant because of individual variations. Taurine uptake did not show such a circadian rhythm either in long or in short photoperiods: it was constant and rather low with large variations from one animal to another.

[Origin of extraorthosympathetic nerve fibers innervating the epiphysis of the rat (study of retrograde transport of horseradish peroxidase)]. / Recherche de l'origine des fibres nerveuses extra-orthosympathiques innervant l'épiphyse du rat (étude du transport rétrograde de la peroxydase de raifort).

After horseradish peroxidase was injected into the rat pineal gland, isolated and rare labelled perikarya appeared in the central nervous system, particularly in the habenula, colliculi, amygdala, paraventricular and suprachiasmatic nuclei, preoptic area and olfactive centers. This indicates that the innervation of the pineal gland is not only orthosympathetic but that some stimuli can be directly transmitted from the brain to the pineal stalk.