Tuberoinfundibular Pathway: What It Is And How This Brain Route Works
Brain pathways are routes that connect different regions of the brain. In this article We will learn about one of the dopaminergic pathways, the tuberoinfundibular pathway This pathway is related to a very important hormone: prolactin.
We will see how important this pathway is, and we will also learn about the other three most important dopaminergic pathways, closely related to schizophrenia or other psychotic disorders.
The tuberoinfundibular pathway is one of the 4 dopaminergic pathways we have in the brain. The other three are: the mesolimbic, mesocortical and nigrostriatal pathways.
Each dopaminergic pathway is actually a brain pathway of neurons that transmit dopamine from one area of the brain to another Dopamine has been, and is, one of the neurotransmitters most related to schizophrenia, as we will see later.
Tuberoinfundibular route: characteristics
At the neuroanatomical level, the tuberoinfundibular pathway projects from the hypothalamus to the anterior pituitary gland. More specifically, it goes from a very specific nucleus of the mediobasal hypothalamus, called the arcuate nucleus (also called 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 influences the secretion of some hormones by the pituitary gland, such as prolactin (this is a hormone that, among other functions, secretes milk during maternity), and which is secreted more specifically in the adenohypophysis. .
Thus, the dopaminergic neurons of 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 also favors the synthesis of somatotropin.
Blockage of the pathway: hyperprolactinemia
Classic antipsychotics that act by reducing dopamine in patients with psychosis or schizophrenia, end up generating the side effect of an abnormal increase in prolactin levels. This occurs because they block D2 (dopamine) receptors, reducing its level and by extension, inhibiting the functioning of the tuberoinfundibular pathway.
Increased levels of prolactin in the blood through the tuberoinfundibular pathway, called hyperprolactinemia, implies a series of symptoms:
On the one hand, it produces an increase in milk secretion in postpartum stages (during breastfeeding), as well as the presence of galactorrhea (spontaneous breast secretions outside the breastfeeding period), gynecomastia (enlargement of the mammary glands) and mastodynia (breast pain).
Besides, Hyperprolactinemia can also cause irregularities in the menstrual cycle in women, visual problems, headache amenorrhea and other possible problems, such as sexual dysfunctions (for example, it significantly affects fertility and reduces sexual desire).
Hyperprolactinemia appears 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 body processes ; Furthermore, and as we have mentioned, some of them have been significantly related to schizophrenia.
Destination and origin
The mesocortical pathway runs from the ventral tegmental area (VTA) of the trunk to various areas of the cortex, especially the limbic cortex and the dorsolateral prefrontal cortex. The mesolimbic pathway runs from the dopaminergic cell bodies of the ventral tegmental area (VTA) to the limbic areas of the brain, such as the nucleus accumbens. Finally, the nigrostriatal pathway goes from the substantia nigra to the basal or striatal ganglia (extrapyramidal system).
Hyperfunctioning of the mesolimbic dopaminergic pathway has been related to the positive symptoms of schizophrenia (Remember that positive symptoms include hallucinations, delusions, disorganized behavior, etc.).
In contrast, hypofunctioning of the mesocortical dopaminergic pathway has been related to the negative symptoms of schizophrenia (avolition, anhedonia, tendency to isolation, affective flattening, etc.).
For its part, the nigrostriatal pathway has been related to other pathologies such as Parkinson’s (its blockade implies a reduction in dopamine levels, and this is related to Parkinson’s, producing symptoms such as akathisia and dystonia). In contrast, an increase in dopamine in the nigrostriatal pathway is related to hyperkinetic disorders such as chorea or tics. If the DA2 receptor in this pathway is chronically blocked, tardive dyskinesia appears.
