Dao of Chinese Medicine by Donald Kendall
Chapter 14 Mechanisms of Action
Highlights/Outline
Roleplayers p 256-7· Naloxone – opiate antagonist – stops analgesic effect of acu
· Periaqueductal gray, etc. – descending inhibitory pathways
· Neurotransmitters
· FMRI – CNS – major integration centers of brain, esp brainstem which integrates visceral and somatic
· Nociceptive DRG neurons in skin - required for de qi sensation
o Two A delta neurons
o C substance P neurons
o Inhibition of them negates acu effect
o Distribute to specific segmental levels of spinal cord
o Proximity to afferent sympathetic visceral neurons allows for somatovisceral/viscerosomatic communication
· Parasympathic afferents
· Group II (secondary) proprioceptive intrafusal neurons of muscle spindles [cause propagated sensation (PS)]
o Patient may or may not be aware of PS
o Normally participate in defensive spinal reflexes such as stabbing by thorn or exposure to hot object – also transmit signals to maintain bodily balance and function
o Needling activates these propriospinal pathways, which promote restorative processes
Overview of process p257
o Superficial stimulation (acupuncture, etc.) affects viscera and CNS via:
1. At same segment of spinal cord that receives sensory input from needling site
a. Somatovisceral responses (certain pts affect certain viscera, especially ones adjacent to pt)
b. Activated ascending spinal cord pathways
c. Supraspinal descending restorative control to affected level
i. Includes pain relief
ii. Control may depend on function of pt
2. Responses involving PS, propriospinal system, CNS processes
3. Method, strength, and duration of manipulation and retention
a. Skin/superficial tissue role in mediating CNS response to needling
Tissue Response to Needling p257-
· Body’s defense and immune functions in response to damage, puncture wounds, insect bites, etc.
o Can be activated by needling
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o Skin contains complex neurovasculoimmune regulatory network
§ Can you say “wei qi”?
§ Cutaneous tissues
§ Fine arterial and venous blood vessels
§ Lymphatic tissue
§ Immune cells
§ Afferent somatic neurons
§ Sympathetic neurons
§ Cutaneous immunity includes mast cells, bradykinin, cutaneous substance P neurons, sympathetic neurons to local blood vessels
· Epidermal cytokines induce and regulate immune responses of skin
§ Skin function associated with neuromodulators, neurohormones, hormones
· Tachykinin substance P stimulates
o Neurokinin 1 (NK1) receptors and
o Kinins, including bradykinin, b1 and b2 receptors
· Needling stimulates afferent substance P neurons VIA cutaneous immune features
o This stimulation of subst P neurons provokes CNS-mediated effects and antidromic axon reflexes
§ Centrally, this influences the HPA axis, which helps maintain homeostasis and immune system function
o Needling anywhere in body produces local acute inflammatory defensive response
o Acupuncture points have more skin sensors and cell types
§ because they are parts of the body that require more or specific types of information from the environment for protection, etc.
§ pricking, wounds, etc. more harmful at these pts than others
§ some are motor pts or golgi tendon organs
§ have higher electrical conductance (also higher along meridian pathways than non points 1 cm lateral)
§ lower electrical impedance
§ tapping along pathway being stimulated can provoke conscious PS (propogated sensation, what is traditionally called ‘qi traveling along the channel’)
§ larger concentration of neural and fine vascular components
§ greater distribution of mast cells
· Acupuncture sensations and associated neurons
o Touch, pressure, numbness – group II neurons
o Pricking sensation – A delta and group III nociceptive neurons
§ Distention and heaviness – group III
o Soreness – group IV
§ Includes unmyelinated cutaneous C neurons
o Most dominant in needling reactions, in order:
§ Lightly myelinated cutaneous A delta neurons (grp III)
§ Unmyelinated cutaneous C neurons (grp IV)
§ Group II fibers
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§ Pain relief effects of these neurons can be blocked with naloxone
· Needle insertion results in visible flare response (reddened area) p259
o Flare response can be inhibited with capsaicin, a crystalline compound that depletes substance P
o Thus the flare response is mediated by cutaneous nociceptive (subst P) afferents
o If nerve function to needling site is interrupted, flare response is absent, and therapeutic influence of needling is negated
o Size, character, and behavior of flare response can indicate vacuity or repletion, and correlate with effectiveness of acupuncture
· This needling response and local inflammatory reaction involves
o Superficial subst P nociceptive and sympathetic neurons
o Interaction between
§ Blood coagulation system (ying) and
§ Immune complement system (wei)
· Six phases of needling induced tissue reaction (only some of activities and role players in each one mentioned here) p 260
1. Vasodilatory – bradykinin and subst P released
2. Nociceptive Excitation – bradykinin B2 excites subst P A delta and C fibers, sustains reaction
3. Chemotactic – attracts immune cells
4. Solubility – clears needle damage products
5. Tissue Repair – local vascular constriction, formation of fibrin and clots
6. Inactivation – degradation of inflammatory agents- cortisol release
· In phase two, the immune defense reaction to the needle is enhanced by the local vasodilatation and stimulates nociceptive neurons, producing de qi, initating stimulation of spinal afferent nerves
· In phase six, inflammatory reactions are shut down, and humoral pathways release substances into blood and CSF
o Pituitary hormones, including ACTH bound with beta lipotropin (LPH)
§ Adrenocorticotropin (ACTH) stimulates the adrenal cortex to produce cortisol and aldosterone.
§ Lipotropic hormone (LPH) may be cleaved to form melanocyte stimulating hormone and endorphins which have analgesic effects
· You can choose needling time according to these 6 phases
o Strong stim and short retention time favors initial phases – true heat, pathogenic factors
§ Strong stim enhances inflammation
§ Short ret time prevents overproduction of anti-inflam properties
o Mild stimulation with long retention assures corticosteroid production
Nociceptive Activation p263
· Needling produces
· Bradykinin B2, which excites
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· afferent nociceptive subst P neurons that supply acupoint, which send high threshold signals to
· several laminae of spinal cord dorsal horn, where
o synaptic junctures stimulate neurons in the
o dorsal lateral funiculus (DLF) and cross
o neurons that ascend along the anterior lateral tract (ALT) on the opposite side of the spinal cord.
· Messages are sent to spinal afferent processing circuits involving
o Various centers of the brain,
o spinal cord,
o muscles,
o blood vessels, and
o internal organs.
· Propriospinal circuits are provoked, which then activate
o spinal motor reflexes and PS along the body surface.
· Sympathetic neural reflexes are also provoked.
· Only a few of these signals are transmitted to the sensory cortex. Most info is directed to the brain stem to activate
o Descending control signals that are sent back down the spinal cord. These supraspinal signals bring about restorative descending control processes.
· (p 264) Substance P nociceptive neurons amplify and sustain tissue reactions to prolong activation of spinal afferent processing systems
o subst P released at needle site and in paravertebral ganglia