24.08.2023
research
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Jaanus Harro
dr. med.
Institute of Chemistry
Chair of Neuropsychopharmacology
Head of Chair, Professor of Psychophysiology
+372 737 6657
+372 510 2798 (5911)

Chair of Neuropsychopharmacology

Pharmacology is an applied science with foundations in chemistry and physiology. The aim of pharmacologists is to evaluate chemical compounds that influence physiological processes in specific ways and, by using these compounds, to figure out how chemical and physiological processes maintain homeostasis and health.

The emerging of neuropsychopharmacology as a field has been driven by the growing collaboration between scientists representing the fundamental sciences and the pharmaceutical industry in the study of the nervous system, the psyche, behaviour, and psychiatric and neurological disorders.

The Division of Neuropsychopharmacology focuses on processes that affect the brain and behavior. In 2026, our focus is on novel drugs that influence RNA m6A methylation and on the role of RNA methylation in explaining inter-individual differences. We also continue our traditional research into the biochemistry of personality traits using animal models, as well as into the potential use of biochemical markers collected in longitudinal studies in precision medicine and in promoting and safeguarding mental health.

Chair's employees

The RNA m6A demethylase gene and neuroticism

Our epitranscriptomic studies in experimental animals are now complemented by the discovery of an association between FTO and neuroticism in a longitudinal analysis of data from the Estonian Children Personality, Behaviour and Health Study (ECPBHS/EstChild). Researchers at the Karolinska Institutet were the first to publish a similar finding; our study additionally points to a possible influence of the macro-environment.

T. Kurrikoff, D. Eensoo, J. Harro. Obesity-related RNA m6A demethylase gene FTO rs1421085 is associated with neuroticism in a longitudinal birth cohort study. Journal of Neural Transmission (2026). https://doi.org/10.1007/s00702-026-03108-0

The first drug that could reduce anxiety through RNA m6A methylation

A representative compound, CHMA1004, from a class of novel drugs developed by Professor Mati Karelson that increase the activity of the RNA m6A methyltransferase complex METTL3/METTL14, reduced anxiety and impulsivity in animal experiments and affected neurotransmitter turnover in the brain as well as the expression of several genes involved in the stress response.

M. Kanarik, K. Liiver, M. Norden, I. Teino, T. Org, K. Laugus, R. Shimmo, M. Karelson, M. Saarma, J. Harro. RNA m6A methyltransferase activator affects anxiety-related behaviours, monoamines and striatal gene expression in the rat. Acta Neuropsychiatrica (2025) 37: e52. DOI: https://doi.org/10.1017/neu.2024.36

Reward seeking without joy makes one vulnerable

For the first time, we compared in a stress experiment the significance of two stable behavioural traits at the same time: a tendency to seek sweets, measured as the amount of sucrose solution consumed during ad libitum feeding, and the capacity for joy, measured as the rate of 50-kHz vocalisations. Chronic stress had the greatest effect on rats whose sucrose intake was higher than that of the others, but whose capacity for joy was lower.

M. Vares, M. Kanarik, K. Kõiv, M. Vares, K. Anja, M. Metelitsa, K. Laugus, H. Tigro, S. Korulu, R. Shimmo, J. Harro. Vulnerability to chronic stress in male rats: Additive effect of low positive affectivity and high hedonic response as measured by sucrose intake. Behavioural Brain Research (2025) 494: 115749. https://www.sciencedirect.com/science/article/pii/S0166432825003365?via%3Dihub

Reward sensitivity and metabolism: integrated differences in coping strategies?

The components of our novel parsing of reward sensitivity, i.e., interest in many rewards versus becoming fixated on a reward, are differently associated with carbohydrate and lipid metabolism, physical activity and aerobic fitness, as well as with energy intake adjusted for body weight. Thus, personality traits and metabolic characteristics converge.

E. Kiive, U. Katus, D. Eensoo, I. Villa, J. Mäestu, T. Veidebaum, J. Harro. Parsing reward sensitivity reveals distinct relationships with energy intake, metabolic markers, physical activity and fitness. Acta Neuropsychiatrica (2025) 37: e8. DOI: https://doi.org/10.1017/neu.2024.63

A rat with depressive traits is more sensitive to attention

Colleagues at Aarhus University have worked for many years with a genetic animal model of depression, or depression risk: the Flinders Sensitive and Flinders Resistant Lines. When “playing” with female weaned and singly housed animals using our method, it emerged that FSL rats, which are prone to depressive traits in adulthood, respond with far more joyful 50-kHz vocalisations, but that their vocalisation is not a stable trait.

L.M. Kai, L.P. Iglesias, K. Kõiv, J. Harro, G. Wegener. Ultrasonic vocalizations in the Flinders Sensitive Line Rat, a genetic animal model of depression. Acta Neuropsychiatrica (2025) 37: e3. DOI: https://doi.org/10.1017/neu.2024.61

Platelet monoamine oxidase activity reflects serotonin release in the brain

Platelet MAO activity is inversely associated with excessive risk-taking behaviour. This is thought to be because the enzyme’s activity reflects the brain’s capacity to release serotonin. In blood samples collected during an experiment conducted by sports physiologists, platelet MAO activity was found to correlate with the exercise-induced increase in prolactin levels. This kind of change in prolactin levels is associated with serotonin release in the brain.

J. Harro, D. Eensoo, S. Suvi, S. Timpmann, V. Ööpik. Prolactin levels increased by physical exercise correlate with platelet monoamine oxidase activity: Evidence linking platelet MAO with serotonin release capacity. Neuroscience Letters (2025) 848: 138116. https://www.sciencedirect.com/science/article/pii/S0304394025000047?via%3Dihub