Reacción a "Reactions: hibernation-like state induced in rats and mice by ultrasound"

The techniques used are very good and of good quality. Also, the development of a small implantable device for research in mice is novel. However, the study does not provide any novel information either on the neuronal control of torpor or on the control of normal thermogenesis. Several decades of study had already proved the role of the preoptic area of the hypothalamus in the control of body temperature and its role in fever. Pioneering works at the beginning of the last century had already shown that warming the preoptic area of the hypothalamus (POA) produced inhibition of thermogenesis and vasodilation (heat dissipation). This response was mediated by a group of neurons able to respond to warm stimuli directly applied to the POA. It was already known that such warm sensitive neurons were capable of sensing temperature through a specific temperature sensor located on their membrane, TRPM2.  

The ultrasound stimulation used in this work is just producing an increase in temperature of this important hypothalamic area, which most luckily results in stimulating the warm neurons through the already known TRPM2 receptor. Then, other than the new technique (ultrasound) to stimulate this area, there is no novel information about the mechanism of torpor that would produce advancement in our scientific knowledge.  

Mice are very small animals compared to humans. The preoptic area of the hypothalamus is a very deep region in the human brain and it would be difficult to imagine that an extracranial stimulus could be effective a targeting such a deep region without interfering with brain regions in between. However implantable microdevice, similar to deep brain stimulation electrodes, could probably be implanted directly into the POA, and this (not without side effects) would be probably applicable. Would it be done? Probably not. Pharmacological approaches, that normally would interfere with a much large area of the brain or the entire body, giving rise to several side effects. This is why we need alternative mechanisms to target more specific areas to treat pathology or maybe to induce hibernation.  

Whether it is important to find alternatives to the pharmacological approaches, I do not think mechanical stimulation, such as deep brain stimulation, ultrasound, and transcranial magnetic stimulation, would help us in being more specific at targeting specific areas. Furthermore, torpor is a complex mechanism, and hypothermia and hypometabolism is just a component of a larger orchestra, that requires the regulation of many factors to be suitable for life. It would be hard to believe that tricking one single area of the brain would make the job. These mice are recovering from hypothermia, but would they survive a long period (up to 6 months) as a true hibernator does?  

In my opinion, the use of refined molecular techniques and genetic implementation would be the future of medicine able to produce targeted molecules that are going to specifically interreact with targeted neurons and functions. However, this would require more investigation, would be less accepted by public opinion, and would be not immediately viable to a large population, as should be subject designed and it would be expensive. This is the reason why mechanical approaches are still in large use and high demand.