Seasonal oscillation of liver-derived hibernation protein complex in the central nervous system of non-hibernating mammals

Abstract

Mammalian hibernation elicits profound changes in whole-body physiology. The liver-derived hibernation protein (HP) complex, consisting of HP-20, HP-25 and HP-27, was shown to oscillate circannually, and this oscillation in the central nervous system (CNS) was suggested to play a role in hibernation. The HP complex has been found in hibernating chipmunks but not in related nonhibernating tree squirrels, leading to the suggestion that hibernationspecific genes may underlie the origin of hibernation. Here, we show that non-hibernating mammals express and regulate the conserved homologous HP complex in a seasonal manner, independent of hibernation. Comparative analyses of cow and chipmunk HPs revealed extensive biochemical and structural conservations. These include liver-specific expression, assembly of distinct heteromeric complexes that circulate in the blood and cerebrospinal fluid, and the striking seasonal oscillation of the HP levels in the blood and CNS. Central administration of recombinant HPs affected food intake in mice, without altering body temperature, physical activity levels or energy expenditure. Our results demonstrate that HP complex is not unique to the hibernators and suggest that the HP-regulated liver-brain circuit may couple seasonal changes in the environment to alterations in physiology.

Growth promotion in pigs by oxytetracycline coincides with down regulation of serum inflammatory parameters and of hibernation‐associated protein HP‐27

“…Furthermore, pig HP‐27 may depress appetite, as has been suggested for bovine HPs injected intracerebroventricularly in mice. Although the latter results have to be interpreted with caution , the lower HP‐27 serum levels found in the OTC group here could be consistent with the observed increased appetite in OTC treated animals . Pro‐inflammatory cytokines are thought to be responsible for (in)appetence, but the present results may be indicative of a new alternate pathway.…”

Metabolic Flexibility: Hibernation, Torpor, and Estivation

“…Taken together these results were interpreted to suggest that HP serves as a circannual and, perhaps, acute hormonal signal triggering hibernation. More recently, however, the HP gene has been shown to exist broadly within placental mammals including nonhibernators such as dolphin but, curiously, not in mouse which undergoes fasting-induced daily torpor (252). In domestic cattle, that do not hibernate, the HP shares many molecular properties with that from the hibernating chipmunk and even oscillates seasonally in a similar way (252).…”

“…More recently, however, the HP gene has been shown to exist broadly within placental mammals including nonhibernators such as dolphin but, curiously, not in mouse which undergoes fasting-induced daily torpor (252). In domestic cattle, that do not hibernate, the HP shares many molecular properties with that from the hibernating chipmunk and even oscillates seasonally in a similar way (252). From a functional standpoint, injection of recombinant cow HP into mice cerebral ventricles reduces food intake, but does not alter MR or T b (252).…”

“…In domestic cattle, that do not hibernate, the HP shares many molecular properties with that from the hibernating chipmunk and even oscillates seasonally in a similar way (252). From a functional standpoint, injection of recombinant cow HP into mice cerebral ventricles reduces food intake, but does not alter MR or T b (252). Such results might be expected to deflate efforts to seek a role for differential gene expression to regulate torpor.…”

Environmental Noise Pollution: Has Public Health Become too Utilitarian?

“…He was exhorting Jenner to measure the core temperature of a hibernating hedgehog. We all have remnants of the genes for hibernation but we don't express them [88]. Similarly, in common with some animals, we possibly all have the genes for reacting to Infrasound, but only some of us express them.…”