Tuberoinfundibular pathway: what is it and how does this pathway in the brain work

Brain pathways are pathways that connect different regions of the brain. In this article we will know one of the dopaminergic pathways, the tuberoinfundibular pathway. This path is linked to a very important hormone: prolactin.

We will see how important this pathway is, and we will also know the other three most important dopaminergic pathways, closely related to schizophrenia or other psychotic disorders.

    dopaminergic pathways

    The tuberoinfundibular pathway is one of the 4 dopaminergic pathways that we have in the brain. The other three are: the mesolimbic route, the mesocortical route and the black band.

    Each dopaminergic pathway is in fact a brain pathway of neurons that carry dopamine from one area of ​​the brain to another. Dopamine has been and is one of the neurotransmitters most closely linked to schizophrenia, as we will see later.

    Tuberoinfundibular pathway: characteristics

    At the neuroanatomical level, the tuberoinfundibular pathway protrudes from the hypothalamus to the anterior pituitary. Specifically, it ranges from a very specific nucleus in the hypothalamus of the midbase, called the arcuate nucleus (also called the tuberal region), to the medial eminence or infundibular region. On the other hand, the term “infundibular” refers to the infundibulum, a structure from which the pituitary gland or pituitary gland develops.

    The tuberoinfundibular pathway has an influence on the secretion of certain hormones by the pituitary gland, such as prolactin (it is a hormone which, among other functions, secretes milk during maternity), and which is secreted more specifically in the adenohypophysis.

    Thus, dopaminergic neurons in this pathway they are usually active and inhibit the release of prolactin; that is, the presence of dopamine in the tuberoinfundibular pathway inhibits the synthesis of prolactin and further promotes the synthesis of somatotropin.

      Blockage of the pathway: hyperprolactinemia

      Classic antipsychotics that work by lowering dopamine in patients with psychosis or schizophreniaEnd up generating the side effect of an abnormal increase in prolactin levels. Indeed, they block D2 receptors (dopamine), reducing their level and by extension, inhibiting the functioning of the tuberoinfundibular pathway.

      The increase in tuberofibular prolactin levels in the blood, called hyperprolactinaemia, involves a number of symptoms:

      On the one hand, it occurs increased milk segregation in the postpartum stages (During breastfeeding), as well as the presence of galactorrhea (spontaneous breast discharge outside the lactation period), gynecomastia (enlarged mammary glands) and mastodynia (breast pain).

      Outraged, hyperprolactinemia can also cause irregularities in a woman’s menstrual cycle, visual problems, headaches, Amenorrhea and other possible problems, such as sexual dysfunction (for example, significantly affects fertility and reduces sexual desire).

      Hyperprolactinemia occurs in both men and women.

        The other dopaminergic pathways

        In addition to the tuberoinfundibular pathway, there are three other dopaminergic pathways that they are involved in different hormonal and bodily processes; Furthermore, and as we have mentioned, some of them have been significantly linked to schizophrenia.

        Destination and origin

        The mesocortical pathway runs from the ventral tegmental area (VTA) of the trunk to various areas of the cortex, particularly the limbic cortex and the dorsolateral prefrontal cortex. The mesolimbic pathway runs from dopaminergic cell bodies in the ventral tegmental zone (VTA) to limbic areas of the brain, such as the nucleus accumbens. Finally, the black streak path goes from the substantia nigra to the basal or striated ganglia (extrapyramidal system).

        Relationship to schizophrenia and Parkinson’s disease

        Hyperfunction of the mesolimbic dopaminergic pathway has been associated with the positive symptoms of schizophrenia (Remember that positive symptoms include hallucinations, delusions, disorganized behavior, etc.).

        On the other hand, hypofunction of the mesocortical dopaminergic pathway has been associated with negative symptoms of schizophrenia (abulia, anhedonia, tendency to isolation, affective flattening, etc.).

        For its part, the black streak path has been linked to other pathologies such as Parkinson’s disease (its blockage involves reduced dopamine levels, and this is linked to Parkinson’s disease, producing symptoms such as akathisia and dystonia). In contrast, an increase in dopamine in the nigrostriatal pathway is associated with hyperkinetic disorders such as chorea or tics. If the DA2 receptor is chronically blocked in this pathway, tardive dyskinesia occurs.

        Bibliographical references:

        • Carlson, NR (2005). Behavioral physiology. Madrid: Pearson Education.
        • Netter, F. (1989). The nervous system. Anatomy and physiology. Barcelona: saved.
        • Rosenweig, M., Breedlove, S., Watson, N. (2005). Psychobiology: an introduction to behavioral, cognitive and clinical neuroscience. Barcelona: Ariel.

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