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Martin Häring‘Opposing roles of the endocannabinoid system in glutamatergic and GABAergic neurons and its role in the serotonergic system’

Abstract :

The endocannabinoid system possesses neuromodulatory functions by influencing the release of various neurotransmitters, including γ-aminobutyric acid (GABA) and glutamate.
Recent findings support the notion that the CB1 receptor on these two neuronal populations might be responsible for the dual effects on anxiety and stress related behaviour. To this end, we could show that the deletion of the CB1 receptor from either GABAergic or glutamatergic neurons resulted in an opposite exploratory behavioural outcome. Furthermore, an antidepressant dose of rimonabant in the forced swim test requires the CB1 receptor on GABAergic neurons. During the last decade growing evidence has suggest that cannabinergic functions depend on serotonergic transmission. In fact, blocking serotonin release attenuated the antidepressant effect of THC. 
Of particular interest seems to be a direct effect of (endo)cannabinoids on serotonergic terminals, as we were able to show that CB1 mRNA and protein is present on serotonergic neurones (Häring et al. 2007). In order to analyse the physiological role of the CB1 receptor on serotonergic neurons we generated a serotonergic-specific CB1 receptor mutant mouse line, using the Cre-loxP system with a tamoxifen dependent Cre recombinase gene under the control of the tryptophane hydroxylase 2 (TPH2) regulatory sequences. Behavioral analyses of mice lacking CB1 receptor in serotonergic neurons revealed changes in anxiety and stress paradigm.

Selected publications

Neuronal populations mediating the effects of endocannabinoids on stress and emotionality.Häring M, Guggenhuber S, Lutz B. Neuroscience. 2012 Jan 2.
Circuit specific functions of cannabinoid CB1 receptor in the balance of investigatory drive and exploration. Häring M, Kaiser N, Monory K, Lutz B. PLoS One. 2011;6(11):e26617. Epub 2011 Nov 1.

Scientific focus :

Short bio

University: Johannes Gutenberg University, Mainz (2001-2006)
Biology Studies (graduated 2006; Dipl. rer. nat.)
(Begin of the Ph.D. studies 1.10.06)
Lund University, Sweden (2003-2004); ERASMUS Exchange
(course language: English)

Giovanni Marsicano du Neurocentre