Spinal p38 activity and analgesic effect after low- and high-intensity electroacupuncture stimulation in a plantar incision rat model.

AIMS: Postoperative pain is a major problem. Electroacupuncture (EA) has been accepted as a useful and low-risk complementary therapy for post-operative pain. Animal studies indicate that surgical incision activates p38 MAPK in the spinal microglia, which critically contributes to post-incisional nociceptive development. How EA affects incision-induced p38 activation is important but yet to be fully elucidated. METHODS: Male adult rats received plantar incision (PI) at the right hind paw followed by 30-min EA of 4-Hz, one of two intensities (3 and 10mA), and at right ST36 (Zusanli) acupoint immediately after PI and for 3 successive days. EA analgesia was evaluated by von Frey fibers and Hargreaves' tests. Spinal p38 activation was examined by immunostaining. In separate groups, SB203580, a p38 inhibitor, was intrathecally injected alone or with EA to test the combining effect on nociception and spinal phospho-p38. KEY FINDINGS: EA of 10-mA significantly ameliorated mechanical allodynia, but 3-mA did not. None of them altered thermal hyperalgesia. Repeated EA could not inhibit phospho-p38 in the PI rats, contrarily, EA per se significantly induced phospho-p38 in the normal rats. Intrathecal SB203580 injection dose-dependently prevented PI-induced allodynia. Combination of low-dose SB203580 and 3-mA EA, which were ineffective individually, profoundly reduce post-PI allodynia. SIGNIFICANCE: We demonstrated that 10-mA EA exerts a significant inhibition against post-PI mechanical hypersensitivity via a p38-independent pathway. Importantly, co-treatment with low-dose p38 inhibitor and 3-mA EA can counteract spinal phospho-p38 to exert strong analgesic effect. Our finding suggests a novel strategy to improve EA analgesic quality.

Comparison of electroacupuncture and morphine-mediated analgesic patterns in a plantar incision-induced pain model.

Electroacupuncture (EA) is a complementary therapy to improve morphine analgesia for postoperative pain, but underlying mechanism is not well-known. Herein, we investigated EA-induced analgesic effect in a plantar incision (PI) model in male Sprague-Dawley rats. PI was performed at the left hind paw. EA of 4 Hz and high intensity or sham needling was conducted at right ST36 prior to PI and repeated for another 2 days. Behavioral responses to mechanical and thermal stimuli, spinal phospho-ERK, and Fos expression were all analyzed. In additional groups, naloxone and morphine were administered to elucidate involvement of opioid receptors and for comparison with EA. EA pretreatment significantly reduced post-PI tactile allodynia for over 1 day; repeated treatments maintained analgesic effect. Intraperitoneal naloxone could reverse EA analgesia. Low-dose subcutaneous morphine (1 mg/kg) had stronger inhibitory effect on PI-induced allodynia than EA for 1 h. However, analgesic tolerance appeared after repeated morphine injections. Both EA and morphine could equally inhibit PI-induced p-ERK and Fos inductions. We conclude that though EA and morphine attenuate postincision pain through opioid receptor activations, daily EA treatments result in analgesic accumulation whereas daily morphine injections develop analgesic tolerance. Discrepant pathways and mechanisms underlying two analgesic means may account for the results.

Improved human mesenchymal stem cell isolation.

Human mesenchymal stem cells (hMSCs) are currently available for a range of applications and benefits and have become a good material for regenerative medicine, tissue engineering, and disease therapy. Before ex vivo expansion, isolation and characterization of primary hMSCs from peripheral tissues are key steps for obtaining adequate materials for clinical application. The proportion of peripheral stem cells is very low in surrounding tissues and organs; thus the recovery ratio will be a limiting factor. In this review, we summarized current common methods used to isolate peripheral stem cells, as well as the new insights revealed to improve the quantity of stem cells and their stemness. These strategies offer alternative ways to acquire hMSCs in a convenient and/or effective manner, which is important for clinical treatments. Improved isolation and mass amplification of the hMSCs while ensuring their stemness and quantity will be an important step for clinical use. Enlarged suitable hMSCs are more clinically applicable for therapeutic transplants and may help people live longer and better.

ADSC therapy in neurodegenerative disorders.

Neurodegenerative disorders, chronic diseases that can severely affect the patient's daily life, include amyotrophic lateral sclerosis, Parkinson's, Alzheimer's, and Huntington's diseases. However, these diseases all have the common characteristic that they are due to degenerative irreversibility, and thus no efficient drugs or therapy methods can mitigate symptoms completely. Stem cell therapy, such as adipose tissue-derived stem cells (ADSCs), is a promising treatment for incurable disorders. In this review, we summarized the previous studies using ADSCs to treat neurodegenerative disorders, as well as their therapeutic mechanisms. We also suggested possible expectations for future human clinical trials involving minimized intracerebroventricular combined with intravenous administration, using different cell lineages to finish complementary therapy as well as change the extracellular matrix to create a homing niche. Depending on successful experiments in relevant neurodegenerative disorders models, this could form the theoretical basis for future human clinical trials.

Increased spinal prodynorphin gene expression in reinflammation-associated hyperalgesia after neonatal inflammatory insult.

BACKGROUND: Neuroplasticity induced by neonatal inflammation is the consequence of a combination of activity-dependent changes in neurons. We investigated neuronal sensitivity to a noxious stimulus in a rat model of neonatal hind-paw peripheral inflammation and assessed changes in pain behaviour at the physiological and molecular levels after peripheral reinflammation in adulthood. RESULTS: A decrease in paw withdrawal latency (PWL) after a heat stimulus was documented in rats that received inflammatory injections in their left hind paws on postnatal day one (P1) and a reinflammation stimulus at postnatal 6-8 weeks of age, compared with normal rats. An increase in the expression of the prodynorphin (proDYN) gene was noted after reinflammation in the spinal cord ipsilateral to the afferents of the neonatally treated hind paw. The involvement of the activation of extracellular signal-regulated kinases (ERK) in peripheral inflammatory pain hypersensitivity was evidenced evident by the increase in phospho-ERK (pERK) activity after reinflammation. CONCLUSIONS: Our results indicate that peripheral inflammation in neonates can permanently alter the pain processing pathway during the subsequent sensory stimulation of the region. Elucidation of the mechanism underlying the developing pain circuitry will provide new insights into the understanding of the early pain behaviours and the subsequent adaptation to pain.

Prenatal exposure to methamphetamine alters the mechanical withdrawal threshold and tonic hyperalgesia in the offspring.

Maternal methamphetamine (MA) abuse during pregnancy has been proved to induce various impacts on the development of infant and child. In this study, we examined whether prenatal exposure to MA would affect the development of nociceptive system by measuring the responses to noxious stimulation in the developing rat. Adult female Sprague-Dawley rats received bi-daily subcutaneous injection of methamphetamine (5mg/kg) or isovolumetric normal saline since the day of mating till the day of delivery. Birth profiles of the offspring including birth length, weight, and body temperature were recorded during the first postnatal month. Mechanical withdrawal thresholds were measured by von Frey filaments on postnatal day (PND) 30 and 60, and hyperalgesic behaviors following plantar formalin injection (2%, 50 microl) were evaluated on PND 60. The birth body weight and length of rats born to MA-injected dam rats (MA group) were significantly lower than those of the control rats during the first postnatal month; however, their body temperature was significantly higher than those of the control rats during the first 3 days after birth. The MA group rats had significantly lower tactile withdrawal values in von Frey test and higher pain scores in the late phase of pain in the formalin test than those of the control rats. There is a gender difference of nociceptive hypersensitivity manifested as that the female MA group rats had significantly lower withdrawal thresholds and higher pain scores in response to formalin injection than the male MA group rats. These results suggest that prenatal MA exposure could predispose an alteration in the development of nociceptive neuronal network, which leads to a long-lasting status of hypersensitivity to pain stimulations in the offspring.

Serotonin reuptake inhibitors attenuate morphine withdrawal syndrome in neonatal rats passively exposed to morphine.

Previous investigations had shown that inhibitor of serotonin reuptake transporter (SERT) could attenuate morphine withdrawal syndrome in adult animals. In the present study, we determined whether postnatal injection of serotonin reuptake inhibitors, fluoxetine, clomipramine, or citalopram, is able to attenuate the expression of the naloxone-precipitated morphine withdrawal syndrome in 5-day-old neonatal Sprauge-Dawley rats born to dams rat that received morphine injection since a week before mating till 5 days after delivery. Withdrawal syndrome of morphine, manifested as frequent abdominal stretching and yawning, was generated by injection of naloxone on postnatal day 5. Pre-injection with fluoxetine, clomipramine, or citalopram, significantly attenuated the naloxone-precipitated syndrome in a dose-dependent manner without apparent side effect. The rank order of inhibitory potency is citalopram=clomipramine>fluoxetine. This result suggests that inhibitor of SERT may be of potential in treating neonatal morphine withdrawal syndrome.

Clinical, biochemical and molecular investigations of three Taiwanese children with Laron syndrome.

Three children of two Taiwanese families were diagnosed with Laron syndrome, two sisters and one boy. Both sets of parents were consanguineous. Clinically, all three presented with the typical craniofacies of Laron syndrome, consisting of prominent forehead and hypoplastic nasal bridge, high-pitched voice, short stature, and central obesity. Biochemically, their levels of serum IGF-I were less than 5 microg/ml before and after an IGF-I generation test, and levels of IGFBP-3 were reduced in all three patients. Sequence analysis of the growth hormone receptor gene revealed that all three carried a homozygous missense D152G mutation in exon 6.

Analysis of pharmacokinetic parameters for assessment of dextromethorphan metabolic phenotypes.

In this study, the metabolic ratios of dextromethorphan to dextrorphan (DM/DX) in plasma were calculated at steady state after administering 2 dosage forms (Medicon) and Detusiv) of DM with different release rates. The urinary metabolic ratio for each subject was also determined based on the total drug concentration in the urine. An analysis of pharmacokinetic parameters for determining the DM metabolic phenotype was conducted. Results demonstrate that double logarithmic correlations between the metabolic ratios based on pharmacokinetic parameters of either AUC(0-tau,ss), C(max,ss), C(min,ss), or C(ave,ss) for Medicon and Detusiv and the urinary metabolic ratios were all significant. Probit plots of the metabolic ratios based on these pharmacokinetic parameters revealed 2 clusters of distribution, representing extensive and intermediate metabolizers. An antimode of 2.0 for total drug based on these pharmacokinetic parameters was determined and correspondingly referred to an antimode of 0.02 for the urinary metabolic ratio to delineate extensive and intermediate metabolizers. This model was also verified to be appropriate when using total plasma concentrations of DM and DX at any time during the period of the dosing interval at steady state to calculate the metabolic ratio for identifying extensive and intermediate metabolizers. Therefore, the metabolic ratio based on the pharmacokinetic parameters of either AUC(0-tau,ss), C(max,ss), C(min,ss), or C(ave,ss) and plasma concentrations of DM and DX in a single blood sample at steady state are proposed as an alternative way to identify phenotypes of CYP2D6.

Dextromethorphan attenuates morphine withdrawal syndrome in neonatal rats passively exposed to morphine.

We had previously found that co-injection of dextromethorphan, an antitussive drug and a non-competitive NMDA receptor antagonist, with morphine into dam rats throughout the pregnancy period could attenuate the naloxone-precipitated morphine withdrawal syndrome in their offspring. In the present study, we further tested whether postnatal injection of dextromethorphan into the neonatal rats or a 3-day co-injection of dextromethorphan with morphine into the dam rats before delivery is also effective. Female Sprague-Dawley rats were bi-daily injected with escalating doses of morphine from a week before mating till the first postnatal week. Withdrawal syndrome of morphine in the offspring, manifested mainly as abdominal stretching, was generated by injection of naloxone on postnatal day 5. Direct injection of dextromethorphan into the offspring effectively reduced the severity of naloxone-precipitated abdominal stretching in a dose-dependent manner. A 3-day co-treatment with dextromethorphan given to the dam rat before delivery also had a similar attenuating effect, but the efficacy was lower than that produced by postnatal injection. Thus, the results from the present study support that dextromethorphan is of potential in treating or preventing neonatal morphine withdrawal syndrome.