Pre-clinical study suggests path toward non-addictive painkillers

Researchers use a compound with a novel mechanism to treat pain in mice without tolerance or physical dependence

Science Daily/October 25, 2017

Indiana University

A pre-clinical study led by Indiana University scientists reports a promising step forward in the search for pain relief methods without the addictive side effects behind the country's current opioid addiction crisis.

The research, which appears in the journal Biological Psychiatry, finds that the use of compounds called positive allosteric modulators, or PAMs, enhances the effect of pain-relief chemicals naturally produced by the body in response to stress or injury. This study also significantly strengthens preliminary evidence about the effectiveness of these compounds first reported at the 2016 Society for Neuroscience Conference in San Diego, California.

"Our study shows that a PAM enhances the effects of these pain-killing chemicals without producing tolerance or decreased effectiveness over time, both of which contribute to addiction in people who use opioid-based pain medications," said Andrea G. Hohmann, a Linda and Jack Gill Chair of Neuroscience and professor in the IU Bloomington College of Arts and Sciences' Department of Psychological and Brain Sciences, who led the study. "We see this research as an important step forward in the search for new, non-addictive methods to reduce pain."

Over 97 million Americans took prescription painkillers in 2015, with over 2 million reporting problems with the drugs. Drug overdoses are the No. 1 cause of death for Americans under 50, outranking guns and car accidents and outpacing the HIV epidemic at its peak.

Medical researchers are increasingly studying positive allosteric modulators because they target secondary drug receptor sites in the body. By contrast, "orthosteric" drugs -- including cannabinoids such as delta-9-tetrahydrocannabinol (THC) and opioids such as morphine -- influence primary binding sites, which means their effects may "spill over" to other processes in the body, causing dangerous or unwanted side effects. Rather than acting as an on/off switch, PAMs act like an amplifier, enhancing only the effects of the brain's own natural painkillers, thereby selectively altering biological processes in the body that naturally suppress pain.

The PAM used in the IU-led study worked by amplifying two brain compounds -- anandamide and 2-arachidonoylglycerol -- commonly called "endocannabinoids" because they act upon the CB1 receptor in the brain that responds to THC, the major psychoactive ingredient in cannabis.

Although the PAM compound enhanced the effects of the endocannabinoids the study found that it did not cause unwanted side effects associated with cannabis -- such as impaired motor functions or lowered body temperature -- because its effect is highly targeted in the brain. The pain relief was also stronger and longer-lasting than drugs that block an enzyme that breaks down and metabolizes the brain's own cannabis-like compounds. The PAM alone causes the natural painkillers to target only the right part of the brain at the right time, as opposed to drugs that bind to every receptor site throughout the body.

The PAMs also presented strong advantages over the other alternative pain-relief compounds tested in the study: a synthetic cannabinoid and a metabolic inhibitor. The analysis' results suggested these other compounds' remained likely to produce addiction or diminish in effectiveness over time.

While the IU-led research was conducted in mice, Hohmann said it's been shown that endocannabinoids are also released by the human body in response to inflammation or pain due to nerve injury. The compounds may also play a role in the temporary pain relief that occurs after a major injury.

"These results are exciting because you don't need a whole cocktail of other drugs to fully reverse the pathological pain in the animals," Hohmann said. "We also don't see unwanted signs of physical dependence or tolerance found with delta-9-tetrahydrocannabinol or opioid-based drugs. If these effects could be replicated in people, it would be a major step forward in the search for new, non-addictive forms of pain relief."

The PAM used in the study was GAT211, a molecule designed and synthesized by Ganesh Thakur at Northeastern University, who is a co-author on the study. The lead author on the study was Richard A. Slivicki, a graduate student in Hohmann's lab in the IU Program in Neuroscience and Department of Psychological and Brain Sciences. Additional authors on the study are Zhili Xu, an IU research fellow; Ken Mackie, IU professor and director of the Gill Center; Pushkar M. Kulkarni at Northeastern University; and Roger G. Pertwee at the University of Aberdeen, Scotland.

This study was supported in part by the National Institutes of Health.

https://www.sciencedaily.com/releases/2017/10/171025105038.htm

Cannabinoids remove plaque-forming Alzheimer's proteins from brain cells

June 29, 2016

Science Daily/Salk Institute

Salk Institute scientists have found preliminary evidence that tetrahydrocannabinol (THC) and other compounds found in marijuana can promote the cellular removal of amyloid beta, a toxic protein associated with Alzheimer's disease.

While these exploratory studies were conducted in neurons grown in the laboratory, they may offer insight into the role of inflammation in Alzheimer's disease and could provide clues to developing novel therapeutics for the disorder.

"Although other studies have offered evidence that cannabinoids might be neuroprotective against the symptoms of Alzheimer's, we believe our study is the first to demonstrate that cannabinoids affect both inflammation and amyloid beta accumulation in nerve cells," says Salk Professor David Schubert, the senior author of the paper.

Alzheimer's disease is a progressive brain disorder that leads to memory loss and can seriously impair a person's ability to carry out daily tasks. It affects more than five million Americans according to the National Institutes of Health, and is a leading cause of death. It is also the most common cause of dementia and its incidence is expected to triple during the next 50 years.

It has long been known that amyloid beta accumulates within the nerve cells of the aging brain well before the appearance of Alzheimer's disease symptoms and plaques. Amyloid beta is a major component of the plaque deposits that are a hallmark of the disease. But the precise role of amyloid beta and the plaques it forms in the disease process remains unclear.

In a manuscript published in June 2016's Aging and Mechanisms of Disease, Salk team studied nerve cells altered to produce high levels of amyloid beta to mimic aspects of Alzheimer's disease.

The researchers found that high levels of amyloid beta were associated with cellular inflammation and higher rates of neuron death. They demonstrated that exposing the cells to THC reduced amyloid beta protein levels and eliminated the inflammatory response from the nerve cells caused by the protein, thereby allowing the nerve cells to survive.

"Inflammation within the brain is a major component of the damage associated with Alzheimer's disease, but it has always been assumed that this response was coming from immune-like cells in the brain, not the nerve cells themselves," says Antonio Currais, a postdoctoral researcher in Schubert's laboratory and first author of the paper. "When we were able to identify the molecular basis of the inflammatory response to amyloid beta, it became clear that THC-like compounds that the nerve cells make themselves may be involved in protecting the cells from dying."

Brain cells have switches known as receptors that can be activated by endocannabinoids, a class of lipid molecules made by the body that are used for intercellular signaling in the brain. The psychoactive effects of marijuana are caused by THC, a molecule similar in activity to endocannabinoids that can activate the same receptors. Physical activity results in the production of endocannabinoids and some studies have shown that exercise may slow the progression of Alzheimer's disease.

Schubert emphasized that his team's findings were conducted in exploratory laboratory models, and that the use of THC-like compounds as a therapy would need to be tested in clinical trials.

In separate but related research, his lab found an Alzheimer's drug candidate called J147 that also removes amyloid beta from nerve cells and reduces the inflammatory response in both nerve cells and the brain. It was the study of J147 that led the scientists to discover that endocannabinoids are involved in the removal of amyloid beta and the reduction of inflammation.

Other authors on the paper include Oswald Quehenberger and Aaron Armando at the University of California, San Diego; and Pamela Maher and Daniel Daughtery at the Salk Institute.

The study was supported by the National Institutes of Health, The Burns Foundation and The Bundy Foundation.

https://www.sciencedaily.com/releases/2016/06/160629095609.htm

Constituents of hashish and marijuana may help to fight inflammation and allergies

June 8, 2007

Science Daily/University of Bonn

Endocannabinoids seem to play an important role in regulating inflammation processes. Scientists have discovered this in experiments on mice. The study may also have implications for therapy. In animal experiments, a solution with an important component made from cannabis reduced allergic reactions of the skin.

Extracts of the hemp plant cannabis are traditionally used as a popular remedy against inflammation. At the beginning of the last century this natural remedy was even available at every chemist's. But due to the intoxicating effect of the component THC (tetrahydrocannabinol) the plant was taken off the chemist's shelves in the 1930s.

THC acts on the cannabinoid receptors, of which there are two types, CB1 and CB2. Both receptors are made such that THC can attach itself to them. In the brain this causes the intoxicating effect of hashish, cannabis and marijuana. But why does the body have CB1 and CB2 anyway" For two decades it has been known that the human body also produces its own cannabinoids. Like THC they can attach themselves to the receptors. The brain scientist Professor Andreas Zimmer from the Bonn Institute of Molecular Psychiatry is investigating what the function of this endocannabinoid system is. 'Mice without CB1 receptors show psychological abnormalities,' he explains. 'By contrast, CB2 regulates the growth of bones, for example.'

Coincidence

However, according to these most recent results, endocannabinoids also seem to play an important part in regulating inflammation processes. As is often the case with important discoveries, coincidence was involved. In scientific experiments mice are given an ear clip, so that researchers can tell them apart.' In most cases the mice can handle this without problems,' Dr. Meliha Karsak, a member of Professor Zimmer's team, explains. 'With our mice this was different. The skin around the ear clips became inflamed.' There are genetically modified strains of mice in which both cannabinoid receptors are dysfunctional.' And it was in precisely these strains that the inflammation occurred,' she explains.

Together with the Bonn dermatologists Dr. Evelyn Gaffal and Professor Thomas Tüting the researchers investigated these findings. Skin rash can be caused by allergens in laboratory mice. 'However, normally these rashes are only minor,' Dr. Gaffal emphasises. 'However, strains of mice in which the cannabinoid receptors are missing react much more intensely. We observed something similar when we blocked the receptors with medication.'

Step on the brakes

When inflammation occurs the endocannabinoids act like someone stepping on the brakes. They prevent the body from doing too much of a good thing and the immune reaction from getting out of control. This is consistent with the fact that at the beginning of the infection the endocannabinoid concentration increased in the mice. 'Apart from that there are strains of mice in which the breakdown of these active substances produced by the body is malfunction-ing,' Evelyn Gaffal says. 'They have an increased endocannabinoid concen-tration in their skin. In our experiments these animals also showed a less marked allergic reaction.'

The results open up new options for the treatment of skin allergies and inflammation. Firstly, drugs which prevent the breakdown of endocannabin-oids look promising. But the old household remedy cannabis could also make a comeback as an ointment. In the experiment on mice this approach has already been successful. 'If we dabbed THC solution on to the animals' skin shortly before and after applying the allergen, a lot less swelling occurred than normal,' Professor Thomas Tüting explains. 'THC attaches itself to cannabin-oid receptors and activates them. In this way the active substance reduces the allergic reaction.' Incidentally, ointment like this would probably not have an intoxicating effect, for this the amount of THC contained would be much too small.

https://www.sciencedaily.com/releases/2007/06/070607171120.htm

Marijuana-like Compounds Suppress the Immune Response

April 26, 2006

Science Daily/American Society for Biochemistry and Molecular Biology

A group of Japanese scientists has discovered that cannabinoids can cause some white blood cells to lose their ability to migrate to the sites of infection and inflammation. These findings, which appear in the May 5 issue of the Journal of Biological Chemistry, could have potential use in the development of novel anti-inflammatory drugs.

The cannabinoids are a group of chemicals that include marijuana. These compounds bind to and activate the body's cannabinoid receptors. There are two types of cannabinoid receptor: the peripheral cannabinoid receptor (CB2) which is predominantly found in immune cells, and the central cannabinoid receptor (CB1) which occurs in the central nervous system.

Recent studies have suggested that CB2 may be involved in a wide range of physiologic phenomena related to immunity, although research on this function is still at an early stage. Among the possible immunological roles for CB2 is an involvement in the initiation of white blood cell migration to sites of infection and inflammation.

In the Journal of Biological Chemistry study, which was featured as a "Paper of the Week", Yumi Tohyama and colleagues used an in vitro model of blood cell migration to study the involvement of CB2 in the recruitment white blood cells. They found that treating the blood cells with compounds that bind to CB2 suppresses the migration of the cells. When they examined the cells, they discovered that they had lost their ability to develop a front/rear polarity, which is something they need to effectively migrate to sites of infection and inflammation.

Because cannabinoids seem to suppress activated white blood cells, Tohyama believes they could have a potential use in the treatment of inflammatory diseases.

The Journal of Biological Chemistry's Papers of the Week is an online feature which highlights the top one percent of papers received by the journal. Brief summaries of the papers and explanations of why they were selected for this honor can be accessed directly from the home page of the Journal of Biological Chemistry online at www.jbc.org.

The American Society for Biochemistry and Molecular Biology (ASBMB) is a nonprofit scientific and educational organization with over 11,000 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions, and industry.

Founded in 1906, the Society is based in Bethesda, Maryland, on the campus of the Federation of American Societies for Experimental Biology. The Society's primary purpose is to advance the sciences of biochemistry and molecular biology through its publications, the Journal of Biological Chemistry, the Journal of Lipid Research, Molecular and Cellular Proteomics, and Biochemistry and Molecular Biology Education, and the holding of scientific meetings.

https://www.sciencedaily.com/releases/2006/04/060426174508.htm  

In parasitic worm infection both the host and the worm produce cannabis-like molecules

August 22, 2018

Science Daily/University of California - Riverside

Like mammals, parasitic worms have an endocannabinoid system that may help the worm and the hosts it infects survive by reducing pain and inflammation in the host, according to a "wild" new discovery by an interdisciplinary research team at the University of California, Riverside.

The research, done on a mouse model, identifies cell signaling pathways associated with the endocannabinoid system that could be targeted to develop therapeutic treatments aimed at eliminating worm infection or improving infection outcomes.

Endocannabinoids are cannabis-like molecules made naturally by our own body to regulate several processes: immune, behavioral, and neuronal. As with cannabis, endocannabinoids can enhance feeding behavior and reduce pain and inflammation.

"Upon worm infection, the host's intestines produce these cannabis-like molecules maybe as a safety net to dampen pain response," said Nicholas V. DiPatrizio, an assistant professor of biomedical sciences at the UCR School of Medicine and co-leader of the research project. "What we now have found is that the worms, too, are producing these natural cannabinoids throughout the infection process and especially when the worms penetrate the skin, further dampening the host's pain response."

Study results appear in the journal Infection and Immunity.

"Until now, no one had investigated endocannabinoids in worm infection," said immunologist and senior author Meera G. Nair, an assistant professor of biomedical sciences in the UCR School of Medicine, who co-led the research project along with DiPatrizio. "We found that endocannabinoids are elevated following worm infection, and they contribute to optimal worm expulsion from the host's body. This is a protective pathway that operates within infection that we were unaware of before. To increase its chances of survival, the worm may use this pathway so the host increases its feeding behavior -- that is, eats more food -- and it can also reduce tissue damage that inflammation and pain cause."

The endocannabinoid system is present in all mammals, but recent studies suggest that it may be more primitive. Indeed, one study reported that black truffle mushrooms make anandamide, a type of endocannabinoid, possibly as a mechanism to attract truffle hogs that eat the truffles and disperse their spores. The worm C. elegans also has an endocannabinoid system that may operate to regulate its feeding.

"This system is known to dampen pain responses," said DiPatrizio, a physiologist specializing in endocannabinoid research. "Upon worm infection, the host's intestines produce these cannabis-like molecules maybe as a safety net to dampen pain response. What we now have found is that the worms, too, are producing these natural cannabinoids throughout the infection process and especially when the worms penetrate the skin, further dampening the host's pain response. This is advantageous to the worm because if the host could detect these parasites, it would respond to kill them. It's a pro-survival signaling pathway in the body that may have a therapeutic advantage in treating worm infection."

Parasitologist Adler R. Dillman, a co-author on the paper, was surprised to find helminths naturally producing cannabis-like molecules in their own bodies.

"We were taken aback by this finding," said Dillman, an assistant professor in the UCR Department of Nematology. "It may be important in other infections as well. Consider that the endocannabinoid pathway is present in almost all the worms we examined in this study. What it is telling us is that the pathway is evolutionarily conserved across a vast number of species. This clearly is an old and important system in the body that predates humans."

Dillman's lab found that N. brasiliensis, a gastrointestinal parasite of rats and a widely-studied helminth parasite, produces endocannabinoids, especially anandamide. A bioinformatic search of parasitic worm databases revealed this system is conserved within many parasitic nematodes, including the most prevalent helminths of man: roundworm and hookworm.

For Nair, this is the team's "wildest discovery, its biggest finding."

"It could impact behavior, pain, and host-helminth interactions," she said. "Without the endocannabinoid system, infected hosts would have bigger worm burdens. In the lab, when we inhibited this pathway in mice, they were worse off -- they ended up with more worms in their bodies."

Nair, DiPatrizio, and Dillman recently received a two-year, $275,000 grant from the National Institutes of Health to further pursue the research and investigate how the endocannabinoid system affects immune response.

"Our current study focused on hookworms; we are ready now to investigate other helminths," Nair said. "We will investigate whether the host and worm induce endocannabinoids so that the host may have less tissue inflammation and may have improved feeding behavior. Since the worms depletes the host of nutrients, it would make sense that they would trigger strategies to improve feeding."

Nair, a hookworm expert, explained that hookworms bite the intestine and feed on blood, leading to micro-injuries and likely localized pain throughout the well-innervated intestine.

"Since endocannabinoids relieve pain and inflammation, local endocannabinoid production may be beneficial for the host, and perhaps the worm to still remain undetected by the host," she said. "We plan to investigate this further."

"The anti-inflammatory endocannabinoid system gives us insight into potential therapeutic targets for not only hookworm infection, but also celiac disease and inflammatory bowel disease," said DiPatrizio, whose laboratory is also the only one at UCR authorized to study the impact of cannabis exposure, which hijacks the endocannabinoid system, on a host of pathologies and behavior, including gastrointestinal function.

Dillman stressed that until now no one knew worms were manipulating the endocannabinoid pathway.

"Our work has provoked more interesting research questions for us to pursue, and could lead to promising treatments," he said. "We are at just the initial point of discovery."

Nair, DiPatrizio, and Dillman were joined in the research by UCR's Hashini M. Batugedara, Donovan Argueta, Jessica C. Jang, Dihong Lu, Jaspreet Kaur, and Shaokui Ge; and the University of Minnesota's Marissa Macchietto.

The research was supported by grants from the National Institutes of Health. The UCR School of Medicine provided additional support.

https://www.sciencedaily.com/releases/2018/08/180822164157.htm

Cannabis link to relieving intestinal inflammation explained

August 13, 2018

Science Daily/University of Massachusetts Medical School

Reports from cannabis users that the drug reduces the symptoms of inflammatory bowel disease (IBD) may finally be explained by new research from the University of Massachusetts Medical School and the University of Bath showing that endocannabinoids help control and prevent intestinal inflammation in mice.

This is the first-time scientists have reported a biological mechanism to explain why some marijuana users have reported beneficial effects from cannabis on intestine inflammation conditions such as ulcerative colitis and Crohn's disease. Researchers hope that their findings will lead to the development of drugs and treatments for gut disorders, which affect millions of people around the world and are caused when the body's immune defenses mistakenly attack the lining of the intestine.

The findings appear in the Journal of Clinical Investigation.

"There's been a lot of anecdotal evidence about the benefits of medical marijuana, but there hasn't been a lot of science to back it up," said Beth A. McCormick, PhD, vice chair and professor of microbiology & physiological systems at UMass Medical School. "For the first time, we have an understanding of the molecules involved in the process and how endocannabinoids and cannabinoids control inflammation. This gives clinical researchers a new drug target to explore to treat patients that suffer from inflammatory bowel diseases, and perhaps other diseases, as well."

The researchers discovered that gut inflammation is regulated by two important processes, which are constantly in flux and responding to changing conditions in the intestinal environment. The first process, identified in previous scientific research, promotes an aggressive immune response in the gut that destroys dangerous pathogens, but which can also damage the lining of the intestine when immune cells attack indiscriminately.

The second pathway, first described in this paper, turns off the inflammation response via special molecules transported across the epithelial cells lining the gut by the same process already known to remove toxins from these cells into the intestine cavity. Crucially, this response requires a naturally-produced molecule called an endocannabinoid, which is very similar to cannabinoid molecules found in cannabis.

If the endocannabinoid isn't present, inflammation isn't kept in balance and it can run unchecked, as the body's immune cells attack the intestinal lining.

McCormick and colleagues believe that because cannabis use introduces cannabinoids into the body, these molecules could help relieve gut inflammation, as the naturally produced endocannabinoids normally would.

"We need to be clear that while this is a plausible explanation for why marijuana users have reported cannabis relieves symptoms of IBD, we have thus far only evaluated this in mice and have not proven this experimentally in humans. We hope, however, that these findings will help us develop new ways to treat bowel diseases in humans" said professor Randy Mrsny from the University of Bath Department of Pharmacy and Pharmacology.

https://www.sciencedaily.com/releases/2018/08/180813173521.htm