Seasonal differences in ventricular proliferation of adult Gallotia galloti lizards.

ABSTRACT

Lizards present neuronal production throughout the telencephalon in their adult state, both naturally and after experimentally induced brain lesions. As in birds, lizards present seasonal behavioural variations. In birds, such variations have been shown to alter neuronal production. In birds and mammals, lack of stimuli or exposure to stress interferes with adult neurogenetic capacity. The effect of this type of study has not been performed with lizards. In the present study we used bromodeoxyuridine to label dividing cells in the ventricular walls of Gallotia galloti lizards during all four seasons and we investigated the effect of captivity on such proliferation. We found that G. galloti presented a particular distribution that differed from that previously described in other reptiles with respect to regions of greater or lesser proliferative rate. In addition, proliferative rate varied seasonally, with greater production of cells in Spring and low production in Autumn and Winter. Proliferative rate was significantly lower throughout the telencephalon and during all seasons in those lizards kept in captivity as compared with wild animals, even though photoperiod and temperature were similar to natural conditions. Our results indicate that cell production in lizards is species-dependent, varies with seasons and is significantly reduced in captive animals.