Written by Andre DP Encarnacion
A study done in the University of the Philippines Manila (UPM) on the effects of solvent addiction on mice has given its members important clues on the common and different ways toluene—commonly known as “rugby”—affects male and female adolescent brains when inhaled repeatedly. Toluene is a common solvent found in paint, paint thinners, and silicone sealants.
In an article published in the journal of Psychopharmacology in December 2024, a team led by Dr. Rohani Cena-Navarro examined the effects of repeated toluene inhalation on male and female rats. The researchers wanted to see how repeated exposure would affect motivational effects of the drug, as well as locomotion, anxiety symptoms, and social and cognitive behavior.
They found that repeated exposure led to significant social and cognitive impairments. The affected rats struggled to interpret social cues, particularly in novel situations, and showed cognitive impairments particularly when assessing the likelihood of rewards for their actions. These findings, researchers noted, mirror impairments shown by humans with inhalant use disorder (IUD).
Notably, the study also revealed key differences between male and female responses. While toluene exposure increased locomotion in male rats, female rats appeared to be more motivated by the drug based on their higher conditioned place preference (CPP) score. This suggests that female rats were more motivated by the drug, spending more time in areas associated with toluene exposure.
Even after 22 days of abstinence, the female rats continued to exhibit a stronger association with the compound. Given this prolonged effect, Cena-Navarro and her team stressed the need for more research on females suffering from IUD, noting that data on this group remains scarce despite not being uncommon in the outside world.
In an interview with GMA News Online, the researchers shared that they are currently testing low-cost treatments for solvent addiction using these animal models.
“This will allow us to develop treatments that are equally effective in both sexes. The use of rats allows us to examine the effects of abused drugs on the brain. Our goal is to reverse these effects so as to restore the brain to its normal state,” Cena-Navarro said in the interview.
“Because addiction has been established as a brain disorder, the clinician can tell the patient, ‘You are not weak. The chemical compound rewires the brain and impairs its decision-making process.’ Rehabilitating the adolescent brain can end the cycle of addictive behavior and relapse so that young people can restore their relationships and plan for the future,” she added.
The study and the treatments it will help create are part of a three-year project, “Novel Approaches to Treatment of Addiction and Depression using Animal Models,” funded by the Department of Science and Technology.