Institutional Scholarship :: Browsing by Subject "Pain -- Physiological aspects"

Browsing by Subject "Pain -- Physiological aspects"

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Affiliative Behavior and Empathetic Response: Sex Differences and Neuroendocrine Factors
(2008) Mutso, Amelia; Sternberg, Wendy
This study investigated the ability of mice to distinguish the emotional state of other mice as an indication of empathetic behavior. The ability to distinguish emotional states was examined by using an overt pain stimulus on a mouse and measuring subsequent approach behavior by another mouse to the mouse in pain. This was used as a model for the affiliation and empathy of one mouse for another, presenting a novel paradigm for measuring affiliation and empathetic approach behavior towards another animal. The ability to identify the pain state of another mouse was examined in both female and male mice. It was found that female mice were better able than males to identify the pain state of another mouse, and, therefore spent significantly more time in proximity to the cagemate in pain than with an unaffected cagemate. Approach behavior in males was not affected by the pain state of another mouse. Since the hormone oxytocin has been shown to play a role in affiliation, its role in the ability to identify emotional states was investigated through a pharmacological manipulation in female mice where female mice were injected with oxytocin. The data from the oxytocin manipulation were inconclusive but suggested further work is necessary to investigate the role of this hormone in empathetic behavior in mice. Future research can use this novel paradigm to further investigate sex differences in empathetic behavior and the role of affiliative hormones in empathetic responses.
Alterations in Hippocampal Neurogenesis and Pain Behavior in Mice: An Experimental Study
(2009) Bergman, Emma; Sternberg, Wendy
Factors that alter neurogenesis are increasingly being investigated as possible treatments for human conditions such as chronic pain, depression, and PTSD. In this study we investigated the influence of housing and running condition on pain behavior and stress induced analgesia (SIA), to address possible connections between pain and neurogenesis in the dentate gyrus of the adult mouse hippocampus. Mice were either tested on an acute pain test (hotplate and tailwithdrawal) or a tonic pain test (formalin test). We report here that exercise and group housing had the effect of enhancing pain behavior, while SIA was moderated mostly by sex. Preliminary results from new granule cell counts indicate that neurogenesis was slightly enhanced in socially housed running animals, supporting the results generated by past research (Stranahan et al., 2006). Living environment can have a profound effect on biological and behavioral outcomes, both influencing changes in neural plasticity and neurogenesis, and peripheral changes in pain sensitivity. In order to further establish the connection between pain and neurogenesis, future research must investigate this relationship using a larger sample.
Competition, Cooperation, and Pain Sensitivity
(2012) Selsor, Margaret; Sternberg, Wendy
Prior research has shown how competition and exercise increase pain tolerance. However, the specific effects of cooperation in competition on pain sensitivity have not been thoroughly examined. In our study, we had 80 subjects (40 males, 40 females; 40 athletes, 40 non-athletes) randomly assigned to one of four conditions: a control task, biking in isolation, biking cooperatively with a confederate, and biking competitively against a confederate, and they completed pre- and post-test pain measures (cold pressor test, thermal scaling, and thermal pain threshold). We had three main hypotheses: (I) subjects in the competitive condition will elicit the greatest analgesic response (followed by cooperative, isolated, and control), (2) athletes will have higher pain tolerances, a greater analgesic response to the exercise conditions, and a larger rate of RPE, and (3) females will have a greater analgesic response to the exercise condition, and males would have a greater pain tolerance overall. Although most of our hypotheses were not supported, we discuss the implications and ideas for future research.
Does Early-Life Pain in Mice Affect Adulthood Pain Sensitivity, Stress Behavior, and Learning Behavior?
(2006) Magid, Jessica R.; Sternberg, Wendy
In this study, the effects of an early-life painful or stressful experience, specifically a surgery or sham surgery, on adulthood pain, stress, and learning behavior were assessed. The surgery was conducted on two samples of male and female CD-1 mice on the day of birth with or without anxiolytic treatment. These groups were then compared, at two different developmental stages, to unhandled CD-1 subjects. Adulthood pain behavior was assessed using the Hot Plate (HP) and Tail Withdrawal (TW) tests, and baseline and stressor-challenged anxiety were tested using the Elevated Plus-Maze (EPM). We also employed the Morris Water-Maze (MWM) to measure learning behavior. Our results indicate that early-life stress (surgery and sham surgery) appears to increase anxiety behavior and neural activation of stress-related areas following a stressor in adulthood. Additionally, age appears to be a factor in overall adulthood pain and stress behavior, and anxiolytic treatment attenuates the effects of an early-life stressor on pain, stress, and learning behavior, although some of these findings only hold for one sex.
I Love You, Don't Hurt Me: The Effect of Relationship Type on Pain Sensitivity After Ostracism
(2009) Banerji, Trina; Sternberg, Wendy
The present study sought to expand the existing literature on the shared pathway of social and physical pain. Because of the shared pathway and necessity of each type of pain, it was predicted that activation of social pain could sensitize physical pain sensitivity. The current study posits that (1) experiencing ostracism should increase physical pain sensitivity, (2) the relationship one has with the source of social rejection can mediate emotional reactions and subsequent physical pain, (3) personality variables can affect reactions to ostracism and subsequent physical pain, and (4) individual perceptions of relationship can affect reactions to ostracism and subsequent physical pain. Ten dyads in romantic partner, friend, and stranger conditions were individually tested for baseline pain sensitivity and asked to fill out relationship measures including commitment and individual attachment style. In a second session, dyads played a ball-tossing game with each other (and two confederates) that was designed to elicit feelings of ostracism. Pain tests were administered immediately after the manipulation. A separate group of control subjects were also tested for pain but experienced inclusion during the ball-tossing game. Results indicated that those in all types of relationships had decreased pain sensitivity after the ostracism manipulation. Males in romantic relationships experienced an increase in pain sensitivity post manipulation. Neither personality nor relationship variables mediated one's reaction to ostracism and subsequent pain sensitivity. Results suggested that ostracism may not elicit emotional distress but emotional numbing that leads to decreased pain sensitivity. Relationship to the source of the ostracism did affect emotional and physical reactions but further research is needed to clarify this relationship.
Long-term Effects of Neonatal Pain on Adulthood Stress Behavior and Neuroendocrinology
(2008) Vora, Aditya; Sternberg, Wendy
Each year, thousands of premature babies are treated using neonatal care comprising of invasive noxious procedures, long term effects of which are unknown. This study utilized a rodent model to study the effects of neonatal pain on adulthood behavioral and hormonal stress response. Subjects were divided into a surgery, sham-surgery and unhandled group. At P0, subjects in the surgery group underwent laparotomy, a noxious stimuli comprising of an incision in the abdominal, subjects in the sham-surgery group underwent the same stress experiences of the surgery group including cryoanesthesia and maternal separation but did not undergo surgery, and subjects in the unhandled group were returned to mothers. Adulthood behavioral stress testing was conducted using the elevated plus maze at baseline and after induced stress. Adulthood hormonal stress response was studied by measuring levels of corticosterone in blood samples taken at baseline and fifteen, thirty and sixty minutes after exposure to a restraint stressor using a corticosterone radioimmunoassay kit. Significant behavioral effects were found in that overall subjects spent more time in the closed versus open arms of the EPM. In addition, corticosterone levels increased over time and there was a trend suggestive of an enhanced corticosterone response in the surgery group. Neonatal pain potentially influences adulthood stress behavior and neuroendocrinology which may account for differences in adulthood pain behavior seen after neonatal pain. However, studies with a greater sample size and alternate measures of EPM data need to be conducted in order to draw more conclusive results.
Pain as a Mediator of Empathetic Response in Mus musculus: Identifying Neuroendocrine Substrates and Sex Differences of Social Approach Behavior
(2008) Tuttle, Alexander H.; Sternberg, Wendy
Recent behavioral research suggests that empathic behaviors may not be limited to humans and higher-order primates. In mice, pain directed behavior appears to be modulated based on the presence and pain status of a conspecific. However, additional indicators of social attachment have yet to be demonstrated in the mouse model. The present study attempts to determine if mice exhibit additional empathy-like behaviors found in other social models. Involvement of the social neuropeptide oxytocin is also evaluated. Results indicate that pain experienced by a familiar cagemate serves as an effective social cue for eliciting approach behavior in female mice, but does not affect male behavior. Furthermore, elevated levels of oxytocin appear to attenuate female approach behavior. Study limitations and future directions are discussed.
Sex Dependent Affiliation Behavior and Empathic Approach in Mus musculus
(2008) Brown, Kara; Sternberg, Wendy
The purpose of this study was to examine the effects of sex and oxytocin on approach behavior in mice elicited by empathy for the pain of another mouse. The approach behavior of a free mouse towards an enclosed mouse was measured during a 30 minute period. Sex differences in approach behavior were observed during the first experiment. Results showed that females approached mice in pain more often than mice not in pain, whereas this distinction between pain and no pain conditions was not present in males. We hypothesized that this effect may be mediated by a “tend and befriend” response to stress produced by oxytocin. Using the same experimental setup to measure approach behavior, oxytocin was administered by subcutaneous injection to female mice. We expected that female mice with increased oxytocin levels would approach a mouse in pain more often than a mouse not in pain. We also predicted that they would approach a mouse in pain more frequently than mice not injected with oxytocin. Results did not demonstrate effects of pain manipulation in the predicted direction. These results most likely stem from a number of unexpected side effects of high doses of oxytocin including its sedative effects. Studies such as these contribute to the larger goal of researchers to establish animal models of social relationships and emotion as a means of better understanding and treating social disorders in humans.
The Effect of Environmental Enrichment on Pain Behavior: Possible Mechanisms
(2011) Buonora, Michele; Sternberg, Wendy
Environmental enrichment—characterized by increased social interaction, exploratory behavior, and physical activity—has been shown to increase hippocampal neurogenesis as well as the physiological response to stress, both of which cause various behavioral changes in mice. The purpose of the current study was to determine the physiological correlate of a third behavioral change following enrichment: altered pain behavior. Male and female mice were housed in enriched or standard conditions and treated with saline, MAM (a neurogenesis blocker), or naloxone (an opioid receptor antagonist) to explore two possible mechanisms: increased neurogenesis, and chronically elevated levels of β-endorphins—endogenous opioids—as a result of HPA-axis stimulation. Results from our study suggest that, while environmental enrichment was unable to consistently alter pain behavior, sex-dependent chronic elevations of β-endorphins might decrease the sensitivity of enriched males to the analgesic effects of opioid administration.
The Effects of Social Housing and Running Exercise on Adult Hippocampal Neurogenesis and Pain Behaviors Alteration in Mice
(2009) Argadjendra, Masjensen; Sternberg, Wendy; Compton, Rebecca J. (Rebecca Jean)
We investigated the effect of housing, physical exercise, or sex-related differences to adult CD-1 mice hippocampal neurogenesis development. 10 days exposure to social housing and physical exercise have been known to promote hippocampal neurogenesis. Sex-related differences in hippocampal neurogensis are investigated. We found no supporting evidences that social housing, access to running wheel, or female gender promoted hippocampal neurogenesis. We conducted two studies to analyze alterations in pain behaviors due to hippocampal neurogenesis. Study 1 examined the Stress Induced Analgesia response resulted from short period of restraint stressors by employing tail withdrawal test and hot plate test. We report that hot plate test is effective in measuring SIA response. A trend of female mice having stronger SIA response is observed. Group differences in hot plate test are dependent on the interactions between sex x running and in sex x housing. Female group housed mice, male individually housed mice, female non-runners, and male runners experienced more SIA response than their respective counterparts. Study 2 examined central sensitization event by employing the formalin test. Formalin injection to hind paw produces enhanced late phase pain behavior from early phase pain behavior. We report that access to running wheel, but not sex or social housing, significantly enhances late phase pain behavior. Group differences in formalin pain behavior are significantly dependent to housing. Access to running wheels only enhances late phase pain behaviors but not early phase pain behaviors.
The Mechanisms of Pain Modulation by Environmental Enrichment
(2011) Drebing, Dan; Sternberg, Wendy
Mice raised in enriched environments display a host of behavioral and physiological differences from mice raised in standard cage housing. Enriched mice show enhanced pain behaviors, as well as elevated levels of neurogenesis and altered hormonal responses to stress. Although the effects of enriched housing on pain behavior have been well described in the literature, no physiological mechanisms by which enriched environments alter pain behavior have been described. The current study aimed to explore two possible mechanisms by which enrichment could alter pain behavior. One plausible physiological mechanism explored was altered endorphin activity as a result of stress. In one 2x2 experiment, mice were raised in either enriched environments or standard housing, and were treated with either naloxone or saline. Naloxone's effect on opioid receptors allowed the relation between endorphins and pain behavior to be explored. Another plausible physiological mechanism explored was the effect of neurogenesis. In a 2x2 experiment, mice were raised in one of two housing conditions, and were treated with either MAM or saline. MAM's neurogenesis blocking effects allowed for the effects of neurogenesis on pain behavior to be explored. The significant finding of this study was an altered level of f3 endorphin sensitivity in enriched animals. The relation of our findings to pain behavior is discussed.
The Relationship between Drug-Induced Neurogenesis and Pain Behavior in Mice.
(2008) Bitler, Elizabeth; Sternberg, Wendy
This experiment aims to study the relationship between neurogenesis and pain by inducing varying amounts of neurogenesis in mice using a pharmacological manipulation and to evaluate the subsequent pain behavior. A muscarinic ACh receptor agonist, galantamine, was used to increase neurogenesis and a nicotinic ACh receptor agonist, nicotine, was intended to decrease neurogenesis. Injections were administered daily for two weeks to two different drug condition groups and a saline control group, with N = 10 male mice and N = 10 female mice in each group. It was hypothesized that rates of neurogenesis (measured by the number of BrdU positive cells/μm³) would vary across condition, with animals receiving nicotine expressing the lowest rate of neurogenesis and animals receiving galantamine expressing the highest rate of neurogenesis. It was additionally hypothesized that pain behavior on the formalin test would vary across condition in the same direction as neurogenesis. Although the directionality was not as hypothesized, there was a significant effect of the drug conditions in the late phase of pain, with saline-treated animals expressing the lowest amount of pain behavior and galantamine-treated animals expressing the highest amount of pain behavior on average. There was also a significant main effect of condition on our measure of neurogenesis, and the directionality of the effect was the same as that of pain behavior. Our results provide evidence for a relationship between drug-induced neurogenesis and pain behavior in mice, which holds implications for further neurogenesis research.
The Relationship Between Neurogenesis and Pain Behavior
(2008) Alspector, Emily; Sternberg, Wendy
One of the most prominent discoveries of recent neuroscience is the finding that neurogenesis, the formation of new neurons, can occur in the adult brain. While it was previously thought that neurogenesis occurs only in developmental stages, recent breakthrough research has revealed novel analyses about the brain, specifically its inherent plastic nature. Plasticity is not just an attribute of the brain; many bodily mechanisms exhibit plastic properties, as well, including the pain pathway. Sensitization, or the lowered sensitivity threshold of pain-responsive receptors with increased stimulation, is one such example of plasticity in the pain response. Interestingly, mechanisms of pain and neurogenesis have been shown to be connected. Research indicates an inverse relationship between pain and neurogenesis: fewer neurons will form as pain is enhanced. Patients with Alzheimer’s disease, a disease in which adult neurogenesis occurs at a slower rate than normal, report a higher pain tolerance. The present study was designed to investigate if the administration of galantamine and nicotine, both of which are acetylcholine agonists but have opposing effects on neurogenesis, have effects on pain behavior associated with varying degrees of neurogenesis. We hypothesize that if neurogenesis increases with galantamine administration and decreases with administration of nicotine, the mice should display significantly more pain behavior in galantamine conditions when compared to both nicotine subjects and controls because of the increased number cells involved in the pain pathway that form in conjunction with new neurons. Such findings would establish a correlation between either increased pain threshold or analgesia and drug-induced neurogenesis. The general trend observed indicated that with increased neurogenesis, the subject exhibited more pain during the formalin test. Limitations and future research are discussed.

Browsing by Subject "Pain -- Physiological aspects"

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