Peter S. Micalos

Understanding the pathophysiology of depression: From monoamines to the neurogenesis hypothesis model - are we there yet?

HighlightsUnderstanding depression pathophysiology is challenging because varying depression symptomatology cannot be explained by single hypothesis.Pathophysiologic mechanisms include: monoamine hypothesis, genetic, environmental, immunologic, endocrine factors and neurogenesis.The Hypothalamo‐Pituitary‐Adrenal axis is the major neurobiological link between these factors and the development of depression. Abstract A number of factors (biogenic amine deficiency, genetic, environmental, immunologic, endocrine factors and neurogenesis) have been identified as mechanisms which provide unitary explanations for the pathophysiology of depression. Rather than a unitary construct, the combination and linkage of these factors have been implicated in the pathogenesis of depression. That is, environmental stressors and heritable genetic factors acting through immunologic and endocrine responses initiate structural and functional changes in many brain regions, resulting in dysfunctional neurogenesis and neurotransmission which then manifest as a constellation of symptoms which present as depression.

Nonpharmacological interventions for pain management in paramedicine and the emergency setting: a review of the literature.

Paramedicine and the emergency medical services have been moving in the direction of advancing pharmaceutical intervention for the management of pain in both acute and chronic situations. This coincides with other areas of advanced life support and patient management strategies that have been well researched and continue to benefit from the increasing evidence. Even though paramedic practice is firmly focused on pharmacological interventions to alleviate pain, there is emerging evidence proposing a range of nonpharmacological options that can have an important role in pain management. This review highlights literature that suggests that paramedicine and emergency medical services should be considering the application of complementary and alternative therapies which can enhance current practice and reduce the use of pharmacological interventions.

cerebral responses to innocuous somatic pressure stimulation following aerobic exercise rehabilitation in chronic pain patients: a functional magnetic resonance imaging study

Objective The purpose of this research was to assess the functional brain activity and perceptual rating of innocuous somatic pressure stimulation before and after exercise rehabilitation in patients with chronic pain. Materials and methods Eleven chronic pain patients and eight healthy pain-free controls completed 12 weeks of supervised aerobic exercise intervention. Perceptual rating of standardized somatic pressure stimulation (2 kg) on the right anterior mid-thigh and brain responses during functional magnetic resonance imaging (fMRI) were assessed at pre- and postexercise rehabilitation. Results There was a significant difference in the perceptual rating of innocuous somatic pressure stimulation between the chronic pain and control groups (P=0.02) but no difference following exercise rehabilitation. Whole brain voxel-wise analysis with correction for multiple comparisons revealed trends for differences in fMRI responses between the chronic pain and control groups in the superior temporal gyrus (chronic pain > control, corrected P=0.30), thalamus, and caudate (control > chronic, corrected P=0.23). Repeated measures of the regions of interest (5 mm radius) for blood oxygen level-dependent signal response revealed trend differences for superior temporal gyrus (P=0.06), thalamus (P=0.04), and caudate (P=0.21). Group-by-time interactions revealed trend differences in the caudate (P=0.10) and superior temporal gyrus (P=0.29). Conclusion Augmented perceptual and brain responses to innocuous somatic pressure stimulation were shown in the chronic pain group compared to the control group; however, 12-weeks of exercise rehabilitation did not significantly attenuate these responses.

Perspectives on biochemical and neurosensory mechanisms for exercise-induced pain inhibition

Purpose: To outline the potential mechanisms and experimental limitations for exercise-induced pain inhibition. Methods: Investigations that applied physical exertion to evoke changes in experimental pain response were reviewed and evaluated for inclusion. Previous research studies were appraised in a historical context to explicate pain measurement and to expound the prospective underlying mechanisms for exercise-induced pain inhibition. Results: The function of pain-modulatory systems during exercise may have evolved to extend performance and survival. Previous studies have implicated the modulation of pain through activation of descending inhibitory pathways and attenuation of ascending pain-related signaling during and after physical exercise. Central and peripheral release of compounds, such as endorphins and endocannabinoids, as well as baroreceptor inhibitory effects on pain have been postulated in exercise-induced pain inhibition. Inhibition of pain with exercise appears to show adaptation, as revealed by enhanced tolerance to pain with exercise training. Conclusion: The diminution of pain with physical exercise has been associated with mediation of pain-related signaling at central and peripheral sites. Application of this finding could extend into human performance and the therapeutic treatment of pain.

Noneffect of Manual Needle Acupuncture on Experimental Pain Parameters in Healthy Young Men

OBJECTIVES The purpose of this study is to assess the effect of manual acupuncture on experimental pain parameters in healthy participants. DESIGN The experimental design was a repeated-measures, three-group pre- and postprocedure. All subjects participated in a control, sham, and acupuncture procedure, separated by 1 week, in a counterbalanced sequence to forestall an order effect. SETTINGS/LOCATION Data were collected in a laboratory environment. SUBJECTS The participants included 12 healthy young men (mean age 21.3 ± 2.6 years; height 183.8 ± 5 cm; weight 77.7 ± 9.5 kg). INTERVENTIONS The control procedure comprised assessing the experimental pain parameters before and after a quiet rest for 20 minutes. The sham procedure was performed with the needle inserted bilaterally 1-1.5 cm outside each acupoint. The manual acupuncture procedure was performed at two bilateral acupoints of LI-4 (Large Intestine 4, Hegu) and ST-44 (Stomach 44, Nei Ting). OUTCOME MEASURES Pain parameters assessed included the pain threshold, nociceptive reflex threshold, and nociceptive reflex amplitude. RESULTS Repeated-measures analysis of variance between pre- and postcontrol, sham, and acupuncture procedures for pain threshold, nociceptive reflex threshold, and nociceptive reflex amplitude revealed no significant difference. CONCLUSIONS Manual acupuncture at bilateral acupoints LI-4 and ST-44 did not show a change in pain threshold, nociceptive flexion reflex threshold, or the nociceptive reflex amplitude in healthy participants.