Investigation of lactate calcium salt-induced β-catenin destabilization in colorectal cancer cells

AIMS

Calcium supplements appear to reduce the risk of developing colorectal cancer (CRC), and it is necessary to clarify the mechanisms by which they exert their effects. In the present study, we investigate the supplementation effect of calcium via lactate calcium salt (CaLa) on CRC cells, focusing on β-catenin destabilization.

MAIN METHODS

The clonogenic assay was performed using different doses of CaLa. The expression level of c-Myc and Cyclin D1 was measured in addition to the confirmation of β-catenin expression in the CRC cells. Glycogen synthase kinase (GSK)-3β expression was also confirmed in order to investigate the mechanism of β-catenin degradation. Tumorigenic ability was confirmed using a xenograft animal model.

KEY FINDINGS

The number of colonies was significantly decreased after 2.5mM CaLa treatment. CaLa-treated CRC cells showed a decrease in the β-catenin expression. The quantitative level of the β-catenin protein was significantly decreased in the CRC cell lysates, hence the expression level of c-Myc and cyclin D1 was significantly decreased following 2.5mM CaLa treatment. We also confirmed that an increased expression of GSK-3β by CaLa is a key pathway in β-catenin degradation. In the xenograft study, tumorigenicity was significantly inhibited to a maximum of 45% in the CaLa-treated group as compared with the control.

SIGNIFICANCE

These results support the idea that calcium supplementation via CaLa contributes to β-catenin degradation and is hypothesized to reduce the risk of CRC. In addition, it indicates the possibility of CaLa being a potential incorporating agent with existing therapeutics against CRC.

Investigation of the pruritus-induced functional activity in the rat brain using manganese-enhanced MRI

PURPOSE

To provide clear information on the activation regions of itching, we investigated the functional activity of cerebral regions in the pruritus-induced rat model using manganese-enhanced magnetic resonance imaging (MEMRI).

MATERIALS AND METHODS

Itching was induced via neonatal capsaicin treatment in Sprague-Dawley rats (itching rats), and scratching behavior of the control, itching, and gabapentin (GBP)-treated itching rats was compared. Then the activated or deactivated brain regions were investigated in the control, itching, and GBP-treated itching rats using a 4.7T MRI system.

RESULTS

While the itching rats engaged in vigorous scratching (121.2 ± 22.4 times), the scratching behavior was decreased in the GBP-treated itching rats (30.6 ± 8.8 times). GBP induced the attenuation of functional activity in two regions -7.10 mm from bregma, in one region -6.65 mm from bregma, and in one region -6.06 mm from bregma. The brain regions related to itching were as follows: parafascicular nucleus, thalamus, superior/inferior colliculus, periaqueductal gray, cingulate cortex, amygdala, midbrain regions, lateral habenula, and hypothalamic areas.

CONCLUSION

Our MEMRI investigation indicates new functional activity of cerebral regions in rats due to the effect of itching or GBP. This information could be used to monitor the therapeutic effects of novel agents or for clinical strategies to treat pathological itch.

Manganese-Enhanced MRI: Biological Applications in Neuroscience

Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn²⁺) enhances MRI contrast in vivo. Due to similarities between Mn²⁺ and calcium (Ca²⁺), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca²⁺ channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models.

Persistent changes in peripheral and spinal nociceptive processing after early tissue injury

It has become clear that tissue damage during a critical period of early life can result in long-term changes in pain sensitivity, but the underlying mechanisms remain to be fully elucidated. Here we review the clinical and preclinical evidence for persistent alterations in nociceptive processing following neonatal tissue injury, which collectively point to the existence of both a widespread hypoalgesia at baseline as well as an exacerbated degree of hyperalgesia following a subsequent insult to the same somatotopic region. We also highlight recent work investigating the effects of early trauma on the organization and function of ascending pain pathways at a cellular and molecular level. These effects of neonatal injury include altered ion channel expression in both primary afferent and spinal cord neurons, shifts in the balance between synaptic excitation and inhibition within the superficial dorsal horn (SDH) network, and a 'priming' of microglial responses in the adult SDH. A better understanding of how early tissue damage influences the maturation of nociceptive circuits could yield new insight into strategies to minimize the long-term consequences of essential, but invasive, medical procedures on the developing somatosensory system.

Juvenile obesity aggravates disease severity in a rat model of atopic dermatitis

PURPOSE

There is increasing epidemiological evidence of an association between childhood obesity and atopic dermatitis, but little is known about the underlying mechanism(s). In the present study, we used a rat model of atopic dermatitis to assess whether juvenile obesity, induced by reduction of litter size, aggravated the signs of atopic dermatitis and, if so, whether this aggravation was associated with changes in plasma concentration of adipokines, such as leptin and adiponectin.

METHODS

Dermatitis was induced by neonatal capsaicin treatment. Body weight, dermatitis score, serum IgE, skin nerve growth factor (NGF), serum leptin and adiponectin, and cytokine mRNA expression in the skin lesion were compared between small (SL, 5 pups) and large litters (LL, 15 pups).

RESULTS

The body weight of juvenile rats up to 6 weeks of age was significantly heavier in the SL group, compared with those in the LL group. The SL group showed more robust development of dermatitis, and higher levels of serum IgE and skin NGF than the LL group. Additionally, the SL group demonstrated higher levels of leptin and pro-inflammatory cytokine mRNA but lower levels of adiponectin than the LL group.

CONCLUSIONS

These results suggest a causal link between a decrease in immunological tolerance, induced by juvenile obesity, and aggravation of atopic dermatitis.

Juvenile obesity aggravates disease severity in a rat model of atopic dermatitis

PURPOSE

There is increasing epidemiological evidence of an association between childhood obesity and atopic dermatitis, but little is known about the underlying mechanism(s). In the present study, we used a rat model of atopic dermatitis to assess whether juvenile obesity, induced by reduction of litter size, aggravated the signs of atopic dermatitis and, if so, whether this aggravation was associated with changes in plasma concentration of adipokines, such as leptin and adiponectin.

METHODS

Dermatitis was induced by neonatal capsaicin treatment. Body weight, dermatitis score, serum IgE, skin nerve growth factor (NGF), serum leptin and adiponectin, and cytokine mRNA expression in the skin lesion were compared between small (SL, 5 pups) and large litters (LL, 15 pups).

RESULTS

The body weight of juvenile rats up to 6 weeks of age was significantly heavier in the SL group, compared with those in the LL group. The SL group showed more robust development of dermatitis, and higher levels of serum IgE and skin NGF than the LL group. Additionally, the SL group demonstrated higher levels of leptin and pro-inflammatory cytokine mRNA but lower levels of adiponectin than the LL group.

CONCLUSIONS

These results suggest a causal link between a decrease in immunological tolerance, induced by juvenile obesity, and aggravation of atopic dermatitis.

Stress-induced pain: a target for the development of novel therapeutics

Although current therapeutics provide relief from acute pain, drugs used for treatment of chronic pain are typically less efficacious and limited by adverse side effects, including tolerance, addiction, and gastrointestinal upset. Thus, there is a significant need for novel therapies for the treatment of chronic pain. In concert with chronic pain, persistent stress facilitates pain perception and sensitizes pain pathways, leading to a feed-forward cycle promoting chronic pain disorders. Stress exacerbation of chronic pain suggests that centrally acting drugs targeting the pain- and stress-responsive brain regions represent a valid target for the development of novel therapeutics. This review provides an overview of how stress modulates spinal and central pain pathways, identifies key neurotransmitters and receptors within these pathways, and highlights their potential as novel targets for therapeutics to treat chronic pain.

Staphylococci: colonizers and pathogens of human skin

 Staphylococci are abundant bacteria of the human skin microbiome. Several species, particularly Staphylococcus aureus and Staphylococcus epidermidis, are opportunistic pathogens and cause significant disease. The human skin serves many functions and here we review its role as an antimicrobial barrier and the staphylococcal mechanisms to colonize and counteract the various stresses present in this niche. Successful colonization is achieved using a diversity of adhesins, surface proteins and secreted enzymes to counteract the antimicrobial peptides, enzymes and lipid matrix components present in the acid mantle. Further mechanisms enable these bacteria to overcome osmotic and acid stresses and desiccation in order to survive the exacting demands of an ever-changing landscape.

Neonatal capsaicin treatment in rats affects TRPV1-related noxious heat sensation and circadian body temperature rhythm

The transient receptor potential vanilloid 1 (TRPV1) is a cation channel that serves as a polymodal detector of noxious stimuli such as capsaicin. Therefore, capsaicin treatment has been used to investigate the physiological function of TRPV1. Here, we report physiological changes induced by treating neonatal rats with capsaicin. Capsaicin (50mg/kg) (cap-treated) or vehicle (vehicle-treated) was systemically administered to newborn SD rat pups within 48 h after birth. TRPV1 expression, intake volume of capsaicin water, and noxious heat sensation were measured 6 weeks after capsaicin treatment. Circadian body temperature and locomotion were recorded by biotelemetry. Expression of Per1, Per2, Bmal1 and Hsf1 (clock genes) was also investigated. Neonatal capsaicin treatment not only decreased TRPV1 expression but also induced desensitization to noxious heat stimuli. Circadian body temperature of cap-treated rats increased significantly compared with that of vehicle-treated rats. Additionally, the amplitude of the circadian body temperature was reversed in cap-treated rats. Expression of the hypothalamic Hsf1 and liver Per2 clock genes followed a similar trend. Therefore, we suggest that these findings will be useful in studying various physiological mechanisms related to TRPV1.

Neonatal bee venom exposure induces sensory modality-specific enhancement of nociceptive response in adult rats

OBJECTIVE

Previous studies have shown that inflammatory pain at the neonatal stage can produce long-term structural and functional changes in nociceptive pathways, resulting in altered pain perception in adulthood. However, the exact pattern of altered nociceptive response and associated neurochemical changes in the spinal cord in this process is unclear.

METHOD

In this study, we used an experimental paradigm in which each rat first received intraplantar bee venom (BV) or saline injection on postnatal day 1, 4, 7, 14, 21, or 28. This was followed 2 months later by a second intraplantar bee venom injection in the same rats to examine the difference in nociceptive responses.

RESULTS

We found that neonatal inflammatory pain induced by the first BV injection significantly reduced baseline paw withdrawal mechanical threshold, but not baseline paw withdrawal thermal latency, when rats were examined 2 months from the first BV injection. Neonatal inflammatory pain also exacerbated mechanical, but not thermal, hyperalgesia in response to the second BV injection in these same rats. Rats exposed to neonatal inflammation also showed up-regulation of spinal NGF, TrkA receptor, BDNF, TrkB receptor, IL-1β, and COX-2 expression following the second BV injection, especially with prior BV exposure on postnatal day 21 or 28.

CONCLUSION

These results indicate that neonatal inflammation produces sensory modality-specific changes in nociceptive behavior and alters neurochemistry in the spinal cord of adult rats. These results also suggest that a prior history of inflammatory pain during the developmental period might have an impact on clinical pain in highly susceptible adult patients.

Biological and neurodevelopmental implications of neonatal pain

Nociceptive pathways are functional following birth. In addition to physiological and behavioral responses, neurophysiological measures and neuroimaging evaluate nociceptive pathway function and quantify responses to noxious stimuli in preterm and term neonates. Intensive care and surgery can expose neonates to painful stimuli when the developing nervous system is sensitive to changing input, resulting in persistent impacts into later childhood. Early pain experience has been correlated with increased sensitivity to subsequent painful stimuli, impaired neurodevelopmental outcomes, and structural changes in brain development. Parallel preclinical studies have elucidated underlying mechanisms and evaluate preventive strategies to inform future clinical trials.

Manganese-enhanced magnetic resonance imaging (MEMRI) reveals brain circuitry involved in responding to an acute novel stress in rats with a history of repeated social stress

Responses to acute stressors are determined in part by stress history. For example, a history of chronic stress results in facilitated responses to a novel stressor and this facilitation is considered to be adaptive. We previously demonstrated that repeated exposure of rats to the resident-intruder model of social stress results in the emergence of two subpopulations that are characterized by different coping responses to stress. The submissive subpopulation failed to show facilitation to a novel stressor and developed a passive strategy in the Porsolt forced swim test. Because a passive stress coping response has been implicated in the propensity to develop certain psychiatric disorders, understanding the unique circuitry engaged by exposure to a novel stressor in these subpopulations would advance our understanding of the etiology of stress-related pathology. An ex vivo functional imaging technique, manganese-enhanced magnetic resonance imaging (MEMRI), was used to identify and distinguish brain regions that are differentially activated by an acute swim stress (15 min) in rats with a history of social stress compared to controls. Specifically, Mn(2+) was administered intracerebroventricularly prior to swim stress and brains were later imaged ex vivo to reveal activated structures. When compared to controls, all rats with a history of social stress showed greater activation in specific striatal, hippocampal, hypothalamic, and midbrain regions. The submissive subpopulation of rats was further distinguished by significantly greater activation in amygdala, bed nucleus of the stria terminalis, and septum, suggesting that these regions may form a circuit mediating responses to novel stress in individuals that adopt passive coping strategies. The finding that different circuits are engaged by a novel stressor in the two subpopulations of rats exposed to social stress implicates a role for these circuits in determining individual strategies for responding to stressors. Finally, these data underscore the utility of ex vivo MEMRI to identify and distinguish circuits engaged in behavioral responses.

Sex differences in pain responses at maturity following neonatal repeated minor pain exposure in rats

There is mounting evidence of long-lasting changes in pain sensitivity in school-age children who were cared for in a neonatal intensive care unit. Such care involves multiple pain exposures, 70% of which are accounted for by heel lance to monitor physiological well-being. The authors sought to model the repeated brief pain resulting from heel lance by administering repeated paw needle stick to neonatal rat pups. Repeated needle stick during the first 8 days of life was sex-specific in altering responses to mechanical and inflammatory stimuli, but not to a thermal stimulus, at maturity. Specifically, neonatal paw needle stick males exhibited significantly greater mechanical sensitivity in response to von Frey hair testing, whereas neonatal paw needle stick females exhibited significantly greater pain behavior scores following hindpaw formalin injection. This is the first study to show such sex-dependent changes in pain responsiveness at maturity in animals having experienced repeated neonatal needle stick pain. These findings support existing evidence that there are long-term sensory sequelae following neonatal pain experiences in rats and further suggest that there are sex-linked differences in the nature of the consequences. If these relationships hold in humans, these findings suggest that even mild painful insults early in life are not without sensory consequences.

Early neonatal inflammation affects adult pain reactivity and anxiety related traits in mice: genetic background counts

Protracted or recurrent pain and inflammation in the early neonatal period may cause long-lasting changes in central neural function. However, more research is necessary to better characterize the long-term behavioral sequelae of such exposure in the neonatal period.

OBJECTIVES

(1) to study whether timing of postnatal exposure to persistent inflammation alters responsiveness to thermal pain in the adult animal; (2) to assess whether animals experiencing early postnatal chronic inflammation display altered anxiety related behavior; (3) to study the importance of genetic background. Newborn mice (outbred strain, CD1 and F1 hybrid strain, B6C3F1) received an injection of Complete Freund's Adjuvant (CFA) or saline on either postnatal day 1 or 14 (PND1; PND14) into the left hind paw. Pain to radiant heat and anxiety were examined in 12-week-old adult animals. Adult baseline PWL was significantly decreased in CD1 mice exposed to CFA on PND 1 and 14 as compared to their saline treated counterparts. B6C3F1 mice exposed to CFA on PND14 showed markedly reduced baseline PWL compared to the PND14 saline group. Persistent inflammation experienced by B6C3F1 mice on PND1 failed to affect baseline adult thermal responsiveness. Adult mice, CD1 and B6C3F1, displayed low anxiety traits only if they had been exposed to persistent inflammation on PND1 and not on PND14. Our research suggests a role for genetic background in modulating long-term behavioral consequences of neonatal persistent inflammation: the data support the hypothesis that pain experienced very early in life differentially affects adult behavioral and emotional responsiveness in outbred (CD1) and hybrid mice (B6C3F1).