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David Julius, Ph. D. Professor, UC San Francisco

David Julius, UC San Francisco

There was a lecture today here at UC Berkeley delivered by David Julius research professor from UC San Francisco entitled, From peppers to peppermints: Natural products as probes of the pain pathway. This was a technical lecture of a very high caliber delivered as a special event to about 100 faculty and students in the Genetics & Plant Biology building. The subject was pain and the molecular operations which occur on various pathways to give our intellect warnings about possible tissue injuries. When these sensory warnings fail, as they sometimes do with diabetics and leprosy victims, the result can be serious tissue damage and even loss of limbs. The study of these neural pathways of pain involves complex organic chemistry and the source of pain chemicals can be found in nature.

There are several sub-classes of somatosensation: touch, proprioception, thermosensation, and pain. When the chemical reasons for these sensations are understood the pharmaceutical industry will be better able to create drugs to alleviate suffering. It becomes important to understand how the different stimuli are encoded. The most common natural pain relieving compounds are aspirin from willows, morphine from poppies, menthol from mint and capsicum from peppers. The chemical actions and reactions of these were discussed with inspiring depth and clarity. With the capsicum compounds there was a sharp temperature threshold for their pain effecting actions at about 43°C and one at about 16°C for the menthols. These are temperatures where potential thermal effects could injure an animal’s flesh and it would appear that some evolutionary constraints had programmed these actions to become effective for this purpose. There must have been some convergence of evolved reactions which appeared to be similar between capsicum and insect and spider venom.

That was a general overview of the lecture but what follows are my speculations on what it might mean as to why I have been having observable effects from my “experiments” with temperature as described in. 1. Poison Oak, Poison Ivy itching cured with hot air, 2. A cure for the common cold using 105°F baths. 3. Cure the common cold with 102°F voluntary fevers, 4. Prevent the common cold with capsaicin, 5. Fever kills cancer by triggering the body’s defenses. Each of these treatments for a physical health problem may have been working because the heat-related stimuli were triggering a response  in some appropriate bodily system. It appeared that with the common cold the stimulus was to the immune system or the macrophages to become more active. Something similar may be happening with the cancer remissions reported which were related to high fevers. In those cases the heat stimulus triggered a more robust and less refined general purpose response which then identified the cancers as being foreign and attacked them. The poison oak relief was created by a momentary flash of pain which seemed to  deactivate the inflammation response. All of these heat related effects may have had a common cause at a molecular level which was why this lecture excited me.

Provocative questions would be:

1. Are hummingbirds protected from infections because they have such high body temperatures when flying? 2. Hummingbirds’ temperature drops to very low levels when they are sleeping, apparently to conserve energy.  So is there a special relationship of their upper and lower temperature regulation to the upper and lower critical temperatures of 43°C and 16°C? 3. Human flu seems to be interactive with bird flu but birds’ normal body temperature is higher than humans, so why is a human immune response to a flu to raise the body temperature? That would be counterproductive. Certainly the small temperature increase itself doesn’t kill the infecting flu organism but what apparently does kill it is the triggering of some immune response. And that is temperature mediated.

Raising one’s body temperature to a mild fever occasionally may be a life prolonging procedure.