Prolactin excess

The most common secretory neoplasm of the anterior pituitary gland is a prolactin-secreting adenoma (prolactinoma). An early symptom of prolactin excess is a milky discharge from the breasts. Because hyperprolactinemia may suppress the secretion of gonadotropic hormones (e.g., LH, FSH), menstrual irregularity, amenorrhea, and infertility may occur in women. In men, gonadotropic hormone dysfunction may lead to reduced libido, sexual impotence, and infertility. 

Agents Used to Treat Syndromes of Prolactin Excess... 

Prolactin has no therapeutic uses. Hyperprolactinemia is a relatively common endocrine abnormality that most often is caused by prolactin-secreting pituitary adenomas. Hyperprolactinemia also can result from hypothalamic or pituitary diseases that interfere with the delivery of inhibitory dopaminergic signals primary hypothyroidism associated with increased TRH levels renal failure treatment with dopamine receptor antagonists. Manifestations of prolactin excess in women include galactorrhea, amenorrhea, and infertihty. in men, hyperprolactinemia causes loss of libido, impotence, and infertility. 

Nevertheless it must also be expected that anything which increases DA function not only controls extrapyramidal function but also reproduces the other central effects of DA i.e. vomiting, a reduction in prolactin secretion and some psychotic manifestations. In excess it may also cause dyskinesias. Despite these problems, the therapy of PD is one of the success stories of neurology. 

Extrapyramidal side-effects generally appear with blockade of dopamine D2 receptors in excess of 80%, whereas clinical efficacy in treating psychosis is associated with 60-70% D2 receptor blockade [12]. Recently, a partial agonist for the D2 receptor known as aripiprazole has been developed, which results in approximately 70% antagonism/30% agonism at the D2 receptor. It is an effective antipsychotic, has low risk for extrapyramidal symptoms, and does not cause elevated levels of prolactin as do the full antagonists at D2 receptors. 

HT model. GAD symptoms may reflect excessive 5-HT transmission or overactivity of the stimulatory 5-HT pathways. Patients with SAD have greater prolactin response to buspirone challenge, indicating an enhanced central serotonergic response. The role of 5-HT in panic disorder is unclear, but it may have a role in development of anticipatory anxiety. Preliminary data suggest that the 5-HT and 5-HT2 antagonist meta-chlorophenylpiperazine causes increased anxiety in PTSD patients. 

The dopamine D2 agonists bromocriptine and cabergoline (pp. 114, 188) inhibit prolactin-releasing AH cells (indications suppression of lactation, prolactin-producing tumors). Excessive, but not normal, growth hormone release can also be inhibited (indication acromegaly) (3). 

A variety of effects of prolactin has been described on normal tissues and cells of the immune system, deriving from rats, mice and humans [21,22], The nature of the effects varies they can be either stimulatory or inhibitory, depending on the system studied and the concentration of prolactin. Thus, in the rat, hypophysectomy leads to impairment of the immune response which can be restored by injection of prolactin [118]. On the other hand, excessively high levels of prolactin can also give rise to an impaired immune response. 

This plant is a relatively little-known member of the sage family, native to southern California. While I am unaware of any clinical studies on the activity of white sage, empirical use indicates that this herb reduces prostatic swelling, inflammation, excessive urination, and mucus discharge. It also acts as an antagonist to the hormone prolactin, which has been shown to increase prostatic... 

While there is no clinical evidence showing that saw palmetto prevents prostate cancer, increased DHT and prolactin levels have been linked to a higher incidence of this disease. Prostate cancer is stimulated by excess androgens, especially in the early stages, and orthodox therapies use treatments that suppress testosterone production. Theoretically, the use of herbs that inhibit the production of DHT and prolactin may reduce the risk of prostatic cancer and/or slow its growth. Dr. William Mitchell, N.D., a remarkable practitioner, teacher, and researcher, has stated that he believes... 

Prolactin is secreted in a pulsatile fashion by the lactotroph cells of the anterior pituitary, with the highest peak concentrations observed during sleep." The secretion of prolactin is regulated primarily by tonic hypothalamic inhibitory effects of dopamine. As described earlier in this chapter and listed in Table 75-1, many factors can affect prolactin secretion. During pregnancy, prolactin serum concentrations rise substantially above normal. All other conditions characterized by excess prolactin serum concentrations, known as hyperprolactinemia, are considered pathologic. 

B37. Bucher, H., Zapf,., Torresani, T., Trader, A., Froesch, E. R., andlllig, R., Insulin-like growth factors I and II, prolactin and insulin in 19 growth hormone-deficient children with excessive, normal or decreased longitudinal growth after operation for cra-niopharygioma. N. Engl. J. Med. 309, 1142-1146 (1983). 

Estrogen is a primary promoter of prolactin release. Of course there are other factors to consider (which we will discuss in a moment) that may trigger excessive prolactin secretion, but the normal trend toward increased prolactin release is due to increased estrogen synthesis. 

The clinical term for excessive release of prolactin is hyperprolactinemia. It is actually a relatively common disorder in humans. There are many causes that initiate the condition including prolactin-secreting tumors and therapy with certain drugs. 

TRH is given as an intravenous bolus, and in normal subjects, elicits a brisk release of both T.SIT and prolactin. Subnormal TSH responses are seen in thyrotoxicosis (excess feedback) and in cases of damage to the pituitary thyrotroph cells. The lack of prolactin response to TRH stimulation may be of value in the diagnosis of a prolactinoma. 

Side effects, toxicity, and conditions that alter sensitivity, as well as the treatment of acute intoxication, are similar to those described for morphine. During long-term administration, there may be excessive sweating, lymphocytosis, and increased concentrations of prolactin, albumin, and globulins in the plasma. Rifampin and phenytoin accelerate the metabolism of methadone and can precipitate withdrawal symptoms. 

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