The female rats are attracted by the male pheromones. When this happens, they release dopamine in the nucleus accumbens of the brain, which is a region involved in the control of behaviour addressed to obtain rewards. This emission depends on the glutamate neurotransmitter. These are the three main conclusions of a study published in the magazine ‘Frontiers in Neuroanatomy’ and produced by a research team of the Universitat de València and the Universitat Jaume I.
Researchers from the Universitat de València and the Universitat Jaume I of Castellón have developed a model to understand how the brain of the rats encode the motivation or reward system. This process is altered in neuropsychiatric diseases such as addiction or depression. The dopamine levels in the neurons of these rodents while they were searching sexual pheromones have been measured through the cerebral microdialysis technique. The effects of the pharmacological manipulation both on this behaviour and on the release of dopamine have been tested.
‘In previous studies of the NeuroFun laboratory we have proved that the female mice are innately attracted by male pheromones. Now, in collaboration with the NeuroPharAd group we have shown that this also happens with female rats’, explains Carmen Agustín, researcher of the NuroFun group of the Cellular Biology, Functional Biology and Physical Anthropology Department of the Universitat de València and the Unit Predepartamental of Medicine of the Universitat Jaume I of Castellón. She highlights that, despite the fact that it is common to confuse the mice and the rats, ‘they are not the same species, they are, in fact, quite different.’
In order to show this sexual attraction thanks to olfactory stimulus in rats, the team has worked with virgin female rats which have grown without male rats, that is to say, they have never seen or smelled any adult. They have noticed that these ones investigate preferably the sawdust of the boxes where the male rats live.
‘The release of dopamine in the nucleus accumbens of the brain happens when the animals are exposed to pleasure stimulus for them and it is also produced by some drugs of abuse. Nevertheless, the exact role that the release of dopamine plays in this region of the brain is still under discussion’, explains María José Sánchez Catalán. She is researcher of the NeuroPharAd group of the Pharmacy and Pharmaceutical Technology and Parasitology Department of the Universitat de València as well as the first author of the article.
The research team has also disclosed that the glutamate neurotransmitter participates in the release of dopamine in the nucleus accumbens. To reach this conclusion, the experts have conducted experiments in which they have avoided the release of glutamate in this region of the brain thanks to antagonist drugs. Blocking this step, the dopamine is not released and the female rats investigate less the sawdust which contains pheromones of the male rat.
‘Our hypothesis is that the release of dopamine is regulated by the activity of neurones which use the glutamate as neurotransmitter and innervate the accumbens from the tonsils, a brain area involved in the emotional behaviour and which receives direct olfactory information’ explains Carmen Agustín. ‘The use of pheromones provides us with an ethologic model, this means, it is based on a spontaneous or animals-typical behaviour. This model can be used to explore in rodents how the brain codifies the motivation and the behaviour aimed at obtaining reward. These mechanisms are modified in diseases such as addiction’, affirms the researcher.
Research Groups
The laboratory in Neuropharmacology of addiction (NeuroPharAd), managed by Ana Polache and Luis Granero, has been studying for more than ten years the neurobiological mechanisms involved in the addiction to ethyl alcohol as well as the development of new therapies to treat this alteration. In particular, the researchers have contributed to understand how the ethyl alcohol products are responsible of many of their addictive effects.
The laboratory of Comparative Functional Neuroanatomy (NeuroFun) was founded in 1990 by Fernando Martínez-García, and in 2002 Enrique Lanuza joined the group as codirector. The researches of the group have focused on the evolution of the tonsils, a brain nucleus involved both in the control of the emotional behaviour and in the olfactory perception as well as in the neurobiology of the behaviours produced by pheromones in mice. The NeuroFun branch run by the professor Martínez-García is in the Universitat Jaume I of Castellón since 2014.
The collaboration of both groups has as its objective the research of the brain circuits which control the motivation and the behaviour aimed at obtaining rewards. These rewards can be natural, such as the sexual pheromones or drugs of abuse such as alcohol.
Article
Sánchez-Catalán MJ, Orrico A, Hipólito L, Zornoza T, Polache A, Lanuza E, Martinez-Garcia F, Granero L and Agustín-Pavón C. (2017) «Glutamate and opioid antagonists modulate dopamine levels evoked by innately attractive male chemosignals in the nucleus accumbens of female rats». Front. Neuroanat. 11:8. doi:10.3389/fnana.2017.00008
Sánchez-Catalán MJ, Orrico A, Hipólito L, Zornoza T, Polache A, Lanuza E, Martinez-Garcia F, Granero L and Agustín-Pavón C. (2017) «Glutamate and opioid antagonists modulate dopamine levels evoked by innately attractive male chemosignals in the nucleus accumbens of female rats». Front. Neuroanat. 11:8. doi:10.3389/fnana.2017.00008
Link:http://journal.frontiersin.org/article/10.3389/fnana.2017.00008/full
Last update: 22 de march de 2017 07:08.
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