Coenzyme NAD+ Postpones Aging in Mice and Worms

August 7, 2017 · Posted in Potential Treatments · Comment 

mouseAging cells seem to lose their ability to repair DNA, while the mitochondria that power cells also become less reliable. A coenzyme called NAD+ may be able to postpone these changes. NAD+, which is found in all living cells, naturally decreases with age.

A 2016 article by Evandro Fei Fang and colleagues in the journal Cell Metabolism reports that giving mice and roundworms supplemental NAD+ postponed cell aging and extended the lives of these animals.

The researchers hope this research might eventually help patients with Alzheimer’s and Parkinson’s’ diseases.

Weight Loss Drug Lorcaserin Cuts Opiate Use in Rats

May 19, 2017 · Posted in Potential Treatments · Comment 

lab ratLorcaserin is a drug approved for weight loss in very obese patients. It stimulates serotonin 5 HT-2c receptors thought to control appetite by inducing the secretion of the polypeptide pro-opiomelanocortin. In a 2017 article in the journal ACS Chemical Neuroscience, researcher Kathryn Cunningham and colleagues reported that the drug had reduced opiate use and craving in rats. Previous research by Cunningham showed that lorcaserin reduced cocaine seeking in rats.

Most treatments for opiate addiction work by occupying opiate receptors so that opiates are prevented from stimulating them, thus reducing the pleasurable effects of the opiates. It is not yet well understood how drugs like lorcaserin that target serotonin 5 HT-2c receptors affect the brain’s reward system.

In the study, rats were trained to self-administer oxycodone. They were also trained to associate certain lights and sounds with oxycodone availability. Lorcaserin reduced the rats’ drug-seeking behavior and also weakened the link between the light and sound cues and the drug-seeking behavior.

Future research may explore whether drugs like lorcaserin can reduce opiate use in people.

Currently, there are a few options to treat opiate addiction. N-acetylcysteine (NAC) is an over-the- counter (nonprescription) drug that has been shown to decrease opiate use in both animals and humans. NAC also decreases use or craving for many other drugs of abuse including cocaine, alcohol, nicotine, and marijuana. NAC reduces the excitatory glutamate signal in the reward area of the brain (the nucleus accumbens) by increasing the number of transporters carrying glutamate out of the synapse and into glial cells. It has an excellent side effects profile and can readily be used in opiate-addicted patients.

Opiate replacement therapy with methadone or the partial opiate agonist buprenorphine is one treatment option for opiate addiction. Buprenorphine is also combined with the opiate antagonist naloxone in a drug called Suboxone, which can reduce opiate use. Naloxone is a pure opiate antagonist that can rapidly reverse the respiratory-suppressing effects of an overdose of opiates.

Disrupting Memories of Cocaine Use Might Prevent Relapse

May 17, 2017 · Posted in Potential Treatments · Comment 

cocaine treatment

Cocaine users who want to abstain from the drug may find that encountering people or places who remind them of past cocaine use can increase their cravings for the drug and lead to relapse. Researchers are studying animals to see if disrupting the link between an environmental cue and the memory of cocaine’s effects could reduce cravings for the drug.

In a 2016 article in the journal Neuropsychopharmacology, researcher Melissa S. Monsey and colleagues reported that in rats, the amnesia-causing natural compound garcinol can weaken the cues that lead to a cocaine-seeking. Garcinol is derived from the rind of kokum (or Garcinia indica) fruit, which is native to the west coast of India.

Monsey and colleagues delivered the garcinol during a period when the rats’ brains were reconsolidating memories that linked an environmental cue with the pleasurable effects of cocaine.

For 12 days, the rats in the study could press a lever and receive an intravenous infusion of cocaine that was paired with a light and a sound. Then the lever stopped working for 8 days. Next, the researchers observed how the rats behaved when the light and sound returned.

The light and sound were meant to remind the rats of the previous times they received cocaine, prompting their brains to reconsolidate the memory linking the light/sound with the pleasurable effects of cocaine.

Half of the rats were given an injection of garcinol during this memory reconsolidation period. While all of the rats continued to seek out cocaine, in the garcinol-treated rats, the light/sound was no longer linked to cocaine. Their cocaine-seeking behavior from then on was unrelated to the light/sound, and the link between the light/sound and cocaine could not be reinstated in these rats.

This research on rats may help clarify how cravings are produced in the brain, and how they might be prevented or treated.

Editor’s Note: In 2012, Yan-Xue Xue and colleagues reported in the journal Science that in humans, psychological techniques can be used to help a patient unlearn the association between an environmental cue and the effects of a drug, using the same theory of the memory reconsolidation period. When patients in recovery from heroin addiction were prompted to revisit memories of heroin use 10 minutes before extinction training (in which they looked at heroin or heroin paraphernalia without receiving the drug), they ended up with fewer cravings for heroin 1, 30, and 180 days later compared to patients who did extinction training without revisiting memories of past heroin use (and thus without opening the memory reconsolidation window, which researchers believe opens 5 minutes to an hour after someone engages in active recall).

Immune Response to Repeated Stress Alters Behavior in Mice

April 12, 2017 · Posted in Course of Illness · Comment 

Laboratory black mouse in the hands of the experimenter

In research presented at the 2016 meeting of the Society of Biological Psychiatry, Jonathan P. Godbout described how an immune reaction to repeated stressors may lead to anxious behaviors in mice.

Mice were repeatedly defeated by a larger animal, a form of stress that produces a depression-like state. This provoked an immune response in the mice—the release of a type of white blood cells called monocytes from the bone marrow into the circulatory system. These inflammatory monocytes then traveled to the brain and spleen, attracted by signaling proteins called chemokines. The monocytes in turn produced inflammatory marker interleukin-1beta.

The defeat stress also provoked a reaction in the central nervous system, where microglia were activated.

These changes produced inflammation and anxiety-like behaviors in the mice. Blocking the microglial activation, monocyte recruitment to the brain, or interleukin-1beta signaling each reversed the anxiety-like behaviors.

Another researcher, Scott Russo, has shown that leukocytes, another type of white blood cells, secrete inflammatory interleukin-6 following defeat stress, and blocking this secretion prevents defeat stress–related behaviors.