The suprachiasmatic nucleus in organotypic slice cultures of the common vole (Microtus arvalis): Comparison of development with rat and hamster and the effect of age

The intrinsic properties of the suprachiasmatic nucleus (SCN), the site of the main circadian pacemaker in mammals, have recently been studied in vitr o by means of organotypic slice culturing. So far, only neonatal rats and m ice have been used for such developmental and functional analyses of the is olated pacemaker. Here, the authors present a comparative developmental stu dy of the SCN of voles, rats, and hamsters in organotypic slice cultures. I n contrast to strictly circadian organization of behavior in rats and hamst ers, common voles (Microtus arvalis) are characterized by large variability in the strength of circadian organization of behavior. It is not known to what extent this variability is reflected in the intrinsic features of the SCN. Cultures were prepared from rat, hamster, and vole pups (6 to 9 days o ld) for the purpose of species comparison. In addition, the authors studied the relation between age and development in cultures from pup (7 to 10 day s old),juvenile (15 to 16 days old), and young adult (1 to 2 months old) vo les. In contrast to the situation in rat and hamster, the most striking fea ture in neonatal voles is the variability in shape of the final, fully deve loped culture and its poor resemblance with the in vivo SCN. The SCN of adu lt voles, however, could be cultured successfully while retaining its morph ological organization. seen in situ. Phase-contrast microscopy and immunocy tochemical staining for vasopressin and glial fibrillary acidic protein rev ealed that cultures of pup and juvenile voles still have potential for neur ogenesis and morphological reorganization. Young voles, therefore, can serv e as a model to study the developmental establishment of a functional circa dian pacemaker, while adult voles allow the study of intrinsic pacemaker pr operties in relation to previously recorded behavior of the donor and aging -related pacemaker dysfunction.