Sex differences in brain activity alter pain therapies

March 2, 2017, Georgia State University
Credit: Wikimedia Commons

A female brain's resident immune cells are more active in regions involved in pain processing relative to males, according to a recent study by Georgia State University researchers.

The study, published in the Journal of Neuroscience, found that when microglia, the brain's resident immune cells, were blocked, female response to opioid medication improved and matched the levels of normally seen in males.

Women suffer from a higher incidence of chronic and inflammatory pain conditions such as fibromyalgia and osteoarthritis. While morphine continues to be one of the primary drugs used for the treatment of severe or , it is often less effective in females.

"Indeed, both clinical and preclinical studies report that females require almost twice as much morphine as males to produce comparable pain relief," said Hillary Doyle, graduate student in the Murphy Laboratory in the Neuroscience Institute of Georgia State. "Our research team examined a potential explanation for this phenomenon, the sex differences in brain microglia."

In healthy individuals, microglia survey the brain, looking for signs of infection or pathogens. In the absence of pain, morphine interferes with normal body function and is viewed as a pathogen, activating the brain's innate and causing the release of inflammatory chemicals such as cytokines.

To test how this sex difference affects morphine analgesia, Doyle gave male and female rats a drug that inhibits microglia activation.

"The results of the study have important implications for the treatment of pain, and suggests that microglia may be an important drug target to improve opioid pain relief in women," said Dr. Anne Murphy, co-author on the study and associate professor in the Neuroscience Institute at Georgia State.

The research team's finding that microglia are more active in brain regions involved in pain processing may contribute to why the incidence rates for various chronic pain syndromes are significantly higher in females than males.

Explore further: New drug target could prevent tolerance and addiction to opioids, neuroscience study finds

More information: H.H. Doyle et al. Sex Differences in Microglia Activity within the Periaqueductal Gray of the Rat: A Potential Mechanism Driving the Dimorphic Effects of Morphine, The Journal of Neuroscience (2017). DOI: 10.1523/JNEUROSCI.2906-16.2017

Related Stories

New drug target could prevent tolerance and addiction to opioids, neuroscience study finds

August 22, 2016
Researchers have identified a brain mechanism that could be a drug target to help prevent tolerance and addiction to opioid pain medication, such as morphine, according to a study by Georgia State University and Emory University.

Researcher finds method to improve morphine's effect on managing pain

October 4, 2013
A method to prevent the body from developing tolerance to morphine, a powerful and commonly used pain medication, has been discovered by a Georgia State University researcher.

Key signaling protein associated with addiction controls the actions of oxycodone on pain

January 17, 2017
RGS9-2, a key signaling protein in the brain known to play a critical role in the development of addiction-related behaviors, acts as a positive modulator of oxycodone reward in both pain-free and chronic pain states, according ...

Targeting brain cells to alleviate neuropathic pain

August 8, 2016
Neuropathic pain – which affects more than 1 million Americans – could be reduced or even eliminated by targeting brain cells that are supposed to provide immunity but, in some instances, do the opposite, causing chronic ...

Recommended for you

MDMA makes people cooperative, but not gullible

November 19, 2018
New research from King's College London has found that MDMA, the main ingredient in ecstasy, causes people to cooperate better—but only with trustworthy people. In the first study to look in detail at how MDMA impacts cooperative ...

How the brain switches between different sets of rules

November 19, 2018
Cognitive flexibility—the brain's ability to switch between different rules or action plans depending on the context—is key to many of our everyday activities. For example, imagine you're driving on a highway at 65 miles ...

Mutation that causes autism and intellectual disability makes brain less flexible

November 19, 2018
About 1 percent of patients diagnosed with autism spectrum disorder and intellectual disability have a mutation in a gene called SETD5. Scientists have now discovered what happens on a molecular level when the gene is mutated ...

Signal peptides' novel role in glutamate receptor trafficking and neural synaptic activity

November 19, 2018
Glutamate is the major excitatory neurotransmitter in the brain, and the postsynaptic expression level of glutamate receptors is a critical factor in determining the efficiency of information transmission and the activity ...

Scientists identify novel target for neuron regeneration and functional recovery in spinal cord injury

November 19, 2018
Restoring the ability to walk following spinal cord injury requires neurons in the brain to reestablish communication pathways with neurons in the spinal cord. Mature neurons, however, are unable to regenerate their axons ...

Study explains behavioral reaction to painful experiences

November 19, 2018
Exposure to uncomfortable sensations elicits a wide range of appropriate and quick reactions, from reflexive withdrawal to more complex feelings and behaviors. To better understand the body's innate response to harmful activity, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.