Open Access. Powered by Scholars. Published by Universities.®
Neuroscience and Neurobiology Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 10 of 10
Full-Text Articles in Neuroscience and Neurobiology
Persistent Peripheral Inflammation Attenuates Morphine-Induced Periaqueductal Gray Glial Cell Activation And Analgesic Tolerance In The Male Rat, Lori N. Eidson, Anne Z. Murphy Phd
Persistent Peripheral Inflammation Attenuates Morphine-Induced Periaqueductal Gray Glial Cell Activation And Analgesic Tolerance In The Male Rat, Lori N. Eidson, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Morphine is among the most prevalent analgesics prescribed for chronic pain. However, prolonged morphine treatment results in the development of analgesic tolerance. An abundance of evidence has accumulated indicating that CNS glial cell activity facilitates pain transmission and opposes morphine analgesia. While the midbrain ventrolateral periaqueductal gray (vlPAG) is an important neural substrate mediating pain modulation and the development of morphine tolerance, no studies have directly assessed the role of PAG‐glia. Here we test the hypothesis that morphine‐induced increases in vlPAG glial cell activity contribute to the development of morphine tolerance. As morphine is primarily consumed for the alleviation of …
Long Term Impact Of Neonatal Injury In Male And Female Rats: Sex Differences, Mechanisms And Clinical Implications, Jamie L. Laprairie, Anne Z. Murphy Phd
Long Term Impact Of Neonatal Injury In Male And Female Rats: Sex Differences, Mechanisms And Clinical Implications, Jamie L. Laprairie, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Over the last several decades, the relative contribution of early life events to individual disease susceptibility has been explored extensively. Only fairly recently, however, has it become evident that abnormal or excessive nociceptive activity experienced during the perinatal period may permanently alter the normal development of the CNS and influence future responses to somatosensory input. Given the significant rise in the number of premature infants receiving high‐technology intensive care over the last twenty years, ex‐preterm neonates may be exceedingly vulnerable to the long‐term effects of repeated invasive interventions. The present review summarizes available clinical and laboratory findings on the lasting …
Neonatal Injury Alters Adult Pain Sensitivity By Increasing Opioid Tone In The Periaqueductal Gray, Jamie L. Laprairie, Anne Z. Murphy Phd
Neonatal Injury Alters Adult Pain Sensitivity By Increasing Opioid Tone In The Periaqueductal Gray, Jamie L. Laprairie, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Studies in both rodents and humans have shown that acute inflammatory pain experienced during the perinatal period produces long-term decreases in pain sensitivity (hypoalgesia) (Grunau et al., 1994a , 2001 ; Ren et al., 2004 ; LaPrairie and Murphy, 2007 ). To date, the mechanisms underlying these long-term adaptations, however, have yet to be elucidated. The present studies tested the hypothesis that neonatal inflammatory pain induces an upregulation in endogenous opioid tone that is maintained into adulthood, and that this increase in opioid tone provides the underlying mechanism for the observed hypoalgesia. On the day of birth (P0), inflammatory pain …
Sex Differences In The Activation Of The Spinoparabrachial Circuit By Visceral Pain, Anne Z. Murphy Phd, Shelby K. Suckow, Malcolm Johns, Richard J. Traub
Sex Differences In The Activation Of The Spinoparabrachial Circuit By Visceral Pain, Anne Z. Murphy Phd, Shelby K. Suckow, Malcolm Johns, Richard J. Traub
Neuroscience Institute Faculty Publications
Women are more sensitive to most noxious visceral stimuli, both in terms of intensity and frequency. The spinoparabrachial (spino-PBn) pathway is an essential neural circuit for the central relay of viscerosensitive information, but studies characterizing the anatomical and physiological characteristics of this pathway have only been conducted in males. Sex differences in the anatomical and/or physiological organization of the spino-PBn may contribute to the sexually dimorphic incidence rate for visceral pain syndromes. Retrograde labeling and colorectal distention (CRD) induced Fos expression was used to delineate the spino-PBn circuit in male and cycling female Sprague-Dawley rats. The ability of morphine to …
Sex Differences In Mu-Opioid Receptor Expression In The Rat Midbrain Periaqueductal Gray Are Essential For Eliciting Sex Differences In Morphine Analgesia, Dayna R. Loyd, Xioaya Wang, Anne Z. Murphy Phd
Sex Differences In Mu-Opioid Receptor Expression In The Rat Midbrain Periaqueductal Gray Are Essential For Eliciting Sex Differences In Morphine Analgesia, Dayna R. Loyd, Xioaya Wang, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Opioid-based narcotics are the most widely prescribed therapeutic agent for the alleviation of persistent pain; however, it is becoming increasingly clear that morphine is significantly less potent in women compared with men. Morphine primarily binds to mu-opioid receptors (MORs), and the periaqueductal gray (PAG) contains a dense population of MOR-expressing neurons. Via its descending projections to the rostral ventromedial medulla and the dorsal horn of the spinal cord, the PAG is considered an essential neural substrate for opioid-based analgesia. We hypothesized that MOR expression in the PAG was sexually dimorphic, and that these sex differences contribute to the observed sex …
Sexually Dimorphic Activation Of The Periaqueductal Gray – Rostral Ventromedial Medullary Circuit During The Development Of Morphine Tolerance In The Rat, Dayna R. Loyd, Michael M. Morgan, Anne Z. Murphy Phd
Sexually Dimorphic Activation Of The Periaqueductal Gray – Rostral Ventromedial Medullary Circuit During The Development Of Morphine Tolerance In The Rat, Dayna R. Loyd, Michael M. Morgan, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Previous studies have shown that tolerance develops to a greater degree in male compared to female rats. The midbrain periaqueductal gray (PAG), and its descending projections to the rostral ventromedial medulla (RVM), provides an essential neural circuit for the antinociceptive effects of opiates and has been implicated in the development of tolerance to morphine. We have previously reported that systemic morphine administration activates a greater proportion of PAG-RVM neurons in male versus female rats; our hypothesis is that if the PAG-RVM pathway is essential for the development of morphine tolerance, then (1) morphine activation of the PAG-RVM pathway should decline …
Androgen And Estrogen (Α) Receptor Localization On Periaqueductal Gray Neurons Projecting To The Rostral Ventromedial Medulla In The Male And Female Rat, Dayna R. Loyd, Anne Z, Murphy Phd
Androgen And Estrogen (Α) Receptor Localization On Periaqueductal Gray Neurons Projecting To The Rostral Ventromedial Medulla In The Male And Female Rat, Dayna R. Loyd, Anne Z, Murphy Phd
Neuroscience Institute Faculty Publications
The periaqueductal gray (PAG) is involved in many gonadal steroid-sensitive behaviors, including responsiveness to pain. The PAG projects to the rostral ventromedial medulla (RVM), comprising the primary circuit driving pain inhibition. Morphine administered systemically or directly into the PAG produces greater analgesia in male compared to female rats, while manipulation of gonadal hormones alters morphine potency in both sexes. It is unknown if these alterations are due to steroidal actions on PAG neurons projecting to the RVM. The expression of androgen (AR) and estrogen (ERα) receptors in the PAG of female rats and within this descending inhibitory pathway in both …
Female Rats Are More Vulnerable To The Long-Term Consequences Of Neonatal Inflammatory Injury, Jamie L. Laprairie, Anne Z. Murphy Phd
Female Rats Are More Vulnerable To The Long-Term Consequences Of Neonatal Inflammatory Injury, Jamie L. Laprairie, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Premature infants are routinely exposed to invasive medical procedures during neonatal intensive care treatment that are largely performed in the absence of anesthetics or analgesics. Data collected to date suggest that exposure to early insult during this time of increased plasticity alters the development of the CNS and influences future pain responses. As previous studies examining the impact of neonatal injury on nociception have been conducted primarily in males, the potential adverse effects on females are not known. Therefore, the present studies were conducted to determine whether neonatal injury differentially impacts male and female sensory thresholds in adulthood. A short …
Morphine Preferentially Activates The Periaqueductal Gray – Rostral Ventromedial Medullary Pathway In The Male Rat: A Potential Mechanism For Sex Differences In Antinociception, Dayna R. Loyd, Michael M. Morgan, Anne Z. Murphy Phd
Morphine Preferentially Activates The Periaqueductal Gray – Rostral Ventromedial Medullary Pathway In The Male Rat: A Potential Mechanism For Sex Differences In Antinociception, Dayna R. Loyd, Michael M. Morgan, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
The midbrain periaqueductal gray (PAG), and its descending projections to the rostral ventromedial medulla (RVM), provide an essential neural circuit for opioid-produced antinociception. Recent anatomical studies have reported that the projections from the PAG to the RVM are sexually dimorphic and that systemic administration of morphine significantly suppresses pain-induced activation of the PAG in male but not female rats. Given that morphine antinociception is produced in part by disinhibition of PAG output neurons, it is hypothesized that a differential activation of PAG output neurons mediates the sexually dimorphic actions of morphine. The present study examined systemic morphine-induced activation of PAG-RVM …
Sex Differences In The Anatomical And Functional Organization Of The Periaqueductal Gray-Rostral Ventromedial Medullary Pathway In The Rat: A Potential Circuit Mediating The Sexually Dimorphic Actions Of Morphine, Dayna R. Loyd, Anne Z. Murphy Phd
Sex Differences In The Anatomical And Functional Organization Of The Periaqueductal Gray-Rostral Ventromedial Medullary Pathway In The Rat: A Potential Circuit Mediating The Sexually Dimorphic Actions Of Morphine, Dayna R. Loyd, Anne Z. Murphy Phd
Neuroscience Institute Faculty Publications
Previous studies have demonstrated that morphine, administered systemically or directly into the PAG, produces a significantly greater degree of antinociception in males in comparison to females. As the midbrain periaqueductal gray (PAG) and its descending projections to the rostral ventromedial medulla (RVM) constitute an essential neural circuit for opioid-based analgesia, the present studies were conducted to determine if sex differences in the anatomical organization of the PAG-RVM pathway, and its activation during persistent inflammatory pain, could account for sex-based differences in opioid analgesia. In the rat, retrograde tracing was combined with Fos immunocytochemistry to investigate sexual dimorphism in the organization …