THE NERVOUS SYSTEM AND ADIPOSE TISSUE
Katharine Dalziel, MD, MBBS, MRCP
1989
...whereas sympathectomy abolishes the
vasoconstrictor reaction, indicating that it is mediated by a local sympathetic axon
reflex.
Extraneous agents, such as large doses of alcohol and morphine, cause increased
lipolysis. This action can be blocked by chemical sympathectomy and is believed to be
due to stimulation of the sympathetic system within the central nervous system.9
Thus the control of metabolism in white fat is complex and dependent on many factors,
both within the adipocytes themselves and in the organism as a whole.
Total chemical sympathectomy in experimental
animals results in loss of shivering and nonshivering thermogenesis, and death within a
few hours.9
Since the effects of sympathectomy on the denervated
area are profound with increased blood flow and warmth and decreased sweating, it is
possible that pain relief is secondary to these phenomena without requiring any sort of
aberrant neural conduction.
This has occurred after stellate ganglion
block37 and lumbar sympathectomy.38 McCallurn and Glynn37 propose that increased
activity in the sympathetic nerves as the effects of the anesthetic block lessen cause
pain, particularly in circumstances where there was abnormal sympathetic activity
before the procedure (such as sympathetic dystrophy). This type of pain is often
resistant to opioid analgesics but may respond well to transcutaneous nerve stimulation.
A similar reduction of fat
mobilization from fat depots occurs after VMH lesions, as after local sympathectomy,
suggesting that the sympathetic pathway to the adipose tissue runs through the VMH.71
These hypothalamic control areas are themselves sensitive to feedback mechanisms.
