Pythons are a well-studied model of postprandial physiological plasticity. Consuming a meal has been shown by past work to evoke a suite of physiological changes in pythons and elicit one of the largest documented increases in post-feeding metabolic rates relative to resting values. However, little is known about how this plasticity manifests in the brains of ball pythons, Python regius. Previous work using the cell-birth marker 5-bromo-12’-deoxyuridine (BrdU) has shown that cell proliferation in the python brain increases six days following meal consumption. This study aimed to confirm these findings and build on them in the long term by tracking the survival and maturation of these newly created cells across a two-month period. We investigated whether these cells differentiated into neurons using double-immunofluorescence for BrdU and a reptile-specific neuronal marker (Fox3). We did not find significantly greater rates of cell proliferation in snakes six days after feeding, but we did observe more newly created cells in neurogenic regions in fed snakes two months after the meal. Feeding did not influence neurogenesis, but feeding does appear to have a neuroprotective effect. More newly created cells survived in fed snakes two months later, particularly in the olfactory bulbs and lateral cortex. These findings shed light on the extent of postprandial plasticity and regional differences in the creation of new neural cells in the brains of ball pythons.

Abstract In homeothermic birds and mammals, several thermoregulatory adaptations have evolved for surviving in unstable, food-restricted conditions. This study focuses on two adaptive mechanisms in pigeons (Columba livia) and quails (Coturnix coturnix japonica): hypothermia and the adaptive use obligatory heat production connected with feeding and digestion. The plasticity of the hypothermic response in fed and fasted birds and birds with restricted feeding was studied in laboratory and outdoor winter conditions. The other objective was to study adaptive timing of digestion, and substitution of facultative thermogenesis by obligatory heat production in cold and at thermoneutrality. The results showed that fasting has a strong influence on the level of nocturnal hypothermia in laboratory conditions: hypothermia becomes progressively deeper when fasting continues. In outdoor conditions, ambient temperature and predation risk modulated the daily body temperature (Tb) pattern of fasting pigeons. In very cold conditions, diurnal Tb of fasted birds also dropped below the normal level of the active phase. Predation risk prevented diurnal hypothermia but also attenuated the depth of nocturnal hypothermia in fasting pigeons. This study provides the first empirical effects of predation risk on hypothermia in starving birds. The study suggests that the presence of crop in pigeons allows adaptive timing of digestion. At thermoneutrality, peak digestion appeared late in the dark phase in birds with fed in the morning. Because the Tb of the birds increases to diurnal levels late in the dark phase, this obligatory heat from digestion can be used to aid re-warming by such timing. On other hand, the results of this study were partly opposite to the classical model of thermoregulatory substitution. In line with the classical model, a postprandial increase in metabolic rate (heat increment of feeding, HIF) was seen at thermoneutrality but not in cold. However, electromyographic measurements showed that there was no postprandial decrease in the intensity of shivering in the fed birds in cold. This indicates that true thermoregulatory substitution may be less common than assumed and suggests a role for facultative thermogenesis in HIF.