http://www.annalsnyas.org/cgi/conten...act/1098/1/312

Part V. Molecular and Protein Markers of Disease


Oxytocin (OT) is a neuropeptide that is produced primarily in the hypothalamus and is best known for its role in mammalian birth and lactation.

Recent evidence also implicates OT in social behaviors, including parental behavior, the formation of social bonds, and the management of stressful experiences. OT is reactive to stressors, and plays a role in the regulation of both the central and autonomic nervous system, including effects on immune and cardiovascular function.
Knowledge of patterns of OT release would be of value in many fields of science and medicine. However, measurements of OT concentration in blood are infrequently performed, and previous attempts to measure OT in saliva have been unsuccessful.

Using a sensitive enzyme immunoassay (EIA) and concentrated samples we were able to detect reproducible changes in salivary OT as a function of lactation and massage. These results indicate that measurements of biologically relevant changes in salivary OT are possible. These results confirm the biological relevance of changes in salivary OT with stressors and support saliva as a noninvasive source to monitor central neuroendocrine function.

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http://courses.washington.edu/conj/b...lactinemia.htm


Prolactin Regulation
Prolactin is the hormone that stimulates milk production in the breast. During pregnancy, prolactin stimulates growth of the breast, but high estrogen and progesterone secretion prevent milk production. After delivery, estrogen and progesterone levels drop, and prolactin stimulates the secretion of milk by alveolar cells in the breast.

Figure 1 illustrates how bursts of prolactin secretion are stimulated so as to maintain milk production during lactation. Suckling by the infant stimulates nipple mechanoreceptors that are connected by neural circuits to neurosecretory cells in the hypothalamus. One type of neurosecretory cell releases the hormone oxytocin from the posterior pituitary. Oxytocin causes milk ejection, in which smooth muscle-like cells called myoepithelial cells contract and push the milk from the glands into the breast ducts so that the infant can easily suck it out. The other neurosecretory cell that is affected releases dopamine at the median eminence. Dopamine acts as a hormone, traveling to the anterior pituitary via the hypophyseal portal vessels to inhibit prolactin secretion by anterior pituitary cells. Suckling, via neural connections inhibits dopamine secretion, increasing prolactin secretion and stimulating milk production in the breast.



Hyperprolactinemia: Causes and Treatments
The most common type of pituitary tumor is a prolactinoma, a tumor that hypersecretes prolactin. Hyperprolactinemia (high prolactin secretion) causes infertility because prolactin inhibits GnRH secretion.

As shown in Figure 2, when GnRH secretion is low, FSH and LH secretion are low and so do not stimulate gamete production and gonadal steroid synthesis. Thus, hyperprolactinemia is an example of infertility due to hypogonadotropic hypogonadism, low gonadal function that results from low gonadotropin secretion. In females this causes a lack of ovulation, which is known as anovulation. Typically, females with hyperprolactinemia will present with amenorrhea (lack of menstruation) and sometimes galactorrhea (abnormal milk production). Prolactinomas seem to be less common in males, but in males hyperprolactinemia also causes infertility and loss of libido due to hypogonadism. Another concern is that decreased gonadal steroid secretion will lead to osteoporosis.
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many of us from the Harvard forum of old -
remember the man who started the research for this - his online name was
"OldBrain"

Yawning was considered until recently a fossil topic
but, like the phoenix, yawning is rising from the ashes !

Yawning is a phylogenetically old, stereotyped event that occurs alone or assiociated with stretching and/or penile erection in humans and in animals from reptiles to birds and mammals under different conditions.

Yawning is a common physiological event that has been described since antiquity. Hypocrates described yawning as an exhaustion of the fumes preceding fever. Modern medicine did not pay a great deal of attention to yawning until the eighties, with advances in neuropharmacology.

Yawning can be divided into 3 distinct phases: a long inspiratory phase, a brief acme and a rapid expiration, frequently but not always associated with stretching, tears, shivering, obstruction of the eustachian canal (causing a reduction in audiologic acuity), followed with a feeling of comfort. The average duration of the yawn is 5 s, (range, 3 to 45 s). The earliest appearance of yawning was observed in a 15-week-old embryo. (see embryology)

This semi-voluntary event increases vigilance and aims to alert when drowsiness occurs ( In animals it subserves behaviour related to stressful situations). Yawning probably has an important role for social communication as well. Excessive or pathological yawning, "chasm", is defined as a compulsive, repetitive action which is not trigered by "physiological" stimuli such as fatigue or boredom, discribed in cases of frontal lobe tumors, encephalitis, progressive supranuclear palsy, following thalamotomy, after electroconvulsive therapy and as an early manifestation of vasovagal response (and a variety of others pathologie-states) and many drugs.

http://www.baillement.com/yawning.html
Drugs that are dopamine antagonists are another cause of hyperprolactinemia. Dopamine antagonists are used to treat schizophrenia. Hyperprolactinemia that is drug induced can be treated by removing the drug, or if that is not possible, by treating the hypogonadism with gonadal steroid hormone replacement.

Pituitary surgery to remove a prolactinoma is expensive and difficult, however it can successfully cure hyperprolactinemia. The first line of treatment for hyperprolactinemia is usually medical treatment with a dopamine agonist. Dopamine agonists reduce prolactin secretion and often cause tumors to shrink so that treatment does not need to go on indefinitely. Dopamine agonists that are approved for the treatment of hyperprolactinemia are bromocriptine and cabergoline.

(Note that cabergoline has been associated with an increased risk for the development of heart valve defects in patients using it as a treatment for Parkinson’s disease. Cabergoline is also an agonist for a certain type of serotonin receptor that stimulates abnormal growth of heart valves. Much lower doses of the drug are needed in the treatment of hyperprolactinemia, 0.5mg twice a week vs. greater than 3mg/day for treating Parkinson’s disease, and so far, no cases of valve dysfunction have been reported from patients being treated for hyperprolactinemia with cabergoline.)