New research indicates that the sex hormones estrogen and progesterone may play a significant role in opioid addiction and relapse. As the U.S. grapples with an ongoing opioid crisis, understanding the biological factors that contribute to addiction is crucial for developing effective treatments.

The Opioid Crisis in Philadelphia and Camden

Philadelphia, Pennsylvania, and Camden, New Jersey, have become epicenters of the opioid epidemic in the United States. In 2022, over 1,170 people died from opioid overdoses in Philadelphia, with more than 300 additional deaths occurring in Camden County. For many individuals, opioid misuse begins with the use of prescription painkillers.

Research Focus: Sex Differences and Opioid Addiction

Neuroscientists are investigating why certain individuals are more prone to developing opioid dependence and addiction when taking prescribed opioids. This research aims to discover better treatments that can reduce drug cravings and prevent relapses among recovering users.

Biological Sex and Addiction Vulnerability

There is growing evidence that biological sex may influence opioid addiction liability and relapse vulnerability. Notably:

• Prescription Rates: Women are more likely than men to be prescribed opioids and to use them.
• Transition to Misuse: Women transition faster from initial use to compulsive misuse.
• Cravings and Withdrawal: Women self-report stronger opioid cravings and may experience more severe withdrawal symptoms compared to men, increasing the risk of relapse.

Role of Sex Hormones

The differences in opioid misuse and relapse susceptibility between men and women may be influenced by varying levels of major sex hormones: testosterone, estrogen, and progesterone. In women, these hormone levels fluctuate naturally across the menstrual cycle and during different life stages such as pregnancy and menopause.

Hormonal Fluctuations and Drug Cravings

To explore the relationship between hormonal fluctuations and opioid cravings, researchers often use rodent models. Rats, with their brief reproductive cycle (estrous cycle) lasting four to five days, provide a good model due to the similarity in hormone fluctuation patterns with humans.

Findings on Cocaine Cravings

Studies in the Loweth lab have shown that cocaine cravings in rats vary across the estrous cycle, peaking around ovulation after estrogen and progesterone levels have surged. Similar observations have been made in humans, where cocaine cravings intensify around ovulation when estrogen levels are elevated.

Opioid Cravings and Hormonal Influence

Although less is known about how hormonal fluctuations affect opioid cravings, existing research suggests that these fluctuations could similarly impact opioid rewards and cravings.

Hormones and Pain Relief

Most current knowledge regarding hormonal influences on opioid drugs comes from studies focused on their pain-relieving effects in humans. These studies suggest:

• Menstrual Cycle Phase: Opioid-induced pain relief appears to be greatest in women during the phase leading up to ovulation when estrogen levels are rising and progesterone levels are low.

The intersection of sex hormones and opioid addiction is a critical area of study, particularly as the opioid crisis continues to claim lives. Understanding how estrogen and progesterone influence opioid cravings and pain relief could lead to more tailored and effective treatment strategies for those struggling with opioid use disorder.

Source: Yahoo News