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The Endocrine System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
The pituitary gland or hypophysis is located in a small cavity in the floor of the skull behind the bridge of the nose. It is about the size of a pea, consisting of two lobes secreting different hormones, and is connected to the hypothalamus by the pituitary stalk. Functions of the anterior (adenohypophysis) and posterior pituitary (neurohypophysis) are regulated by the hypothalamus, which also regulates thirst, appetite and caloric intake, sleep-wake behavior, emotions, autonomic balance, and cognition (a knowing or recognition).
The Role of Oxytocin in Parturition
Published in Gabor Huszar, The Physiology and Biochemistry of the Uterus in Pregnancy and Labor, 2020
We have also measured plasma OT levels in two rabbits with spinal cord transsections at levels T5 and T9, respectively. Both rabbits had spontaneous delivery at the expected time, and the concentration of OT during labor rose to levels seen in intact parturient rabbits.49 The reflex activation of the neurohypophysis during labor must, therefore, be mediated by the thoracic or cervical ganglionic chain rather than through the spinal cord. The involvement of the sympathetic system in OT release has recently been demonstrated.50 This chain is intact in most paraplegics; thus, the occurrence of spontaneous labor in paraplegic women does not exclude OT as the activating agent of myometrial contractions during labor.
Changing the Paradigm from Neurochemical to Neuroelectrical Models
Published in Hanno W. Kirk, Restoring the Brain, 2020
Neuromodulators are typically released from neurons and affect groups of other neurons or effector cells that have appropriate receptors. These often act through what are known as second messengers. Neurohormones, on the other hand, are released from neurons into the circulation and affect cells at a distant site. An example of this would be the release of oxytocin from the neurohypophysis to induce labor. It is important to note that many such receptors previously thought to reside only within the nervous system have also been found in the gut, the circulatory system, and the immune system. The chemical messenger model posits that brain function is dependent on proper “levels” of neurochemicals within its circuitry. For example, it has long been thought that low levels of the neurotransmitter serotonin are responsible for symptoms of depression. Further, it has been demonstrated that molecules such as enkephalins and endorphins are important in mediating pain transmission at both physical and psychological levels. Moreover, endorphins may be involved in what is popularly referred to as the “runner’s high”, because vigorous exercise may stimulate its release. A huge proportion of the pharmaceutical industry is based on manipulation of neurochemistry to alter brain function.
Complete and Uneventful Recovery in a Case of Lymphocytic Hypophysitis Causing a Third Nerve Palsy
Published in Neuro-Ophthalmology, 2023
Jamie M. Nord, Paras P. Shah, Rashmi Verma
The most common symptoms of LH are related to mass effect. Headache is the most reported early symptom, which 60% of patients report on diagnosis.11 These headaches may be severe, generalised, retro-orbital, or bitemporal. Forty percent of patients have visual field deficits due to optic chiasm compression.3 Patients also describe symptoms of adenohypophyseal hypofunction including fatigue, lethargy, loss of libido, amenorrhoea, dizziness, nausea and vomiting. ACTH is the most common hormone deficiency, occurring in 65% of patients.12 Thirty percent of patients experience hyperprolactinaemia, which can result in amenorrhoea or galactorrhoea in women and sexual dysfunction in men.13 However, given that most women present in pregnancy or the postpartum period, these symptoms are difficult to identify. Some patients also have symptoms of neurohypophysis involvement from diabetes insipidus.1,14
Histopathological evaluation of the effects of dexmedetomidine against pituitary damage ınduced by X-ray irradiation
Published in Biomarkers, 2023
Filiz Mercantepe, Levent Tumkaya, Tolga Mercantepe, Sema Rakici
On examination of sections stained with haematoxylin and eosin under a light microscope, the pituitary tissues of the control group had adenohypophysis tissue composed of normal chromophobic acidophilic and basophilic cells. We also observed normal pituicytes and neurohypophysis tissue with non-myelinated axons (Figure 1a and b, Table 2, HHS: 0.5(0-1)). In contrast, in sections obtained from the x-ray irradiation group, we observed many necrotic chromophobic and chromophilic cells in adenohypophysis tissue accompanied by diffuse vacuolar accumulation in the cytoplasm. Similarly, we determined necrotic pituicytes with diffuse vacuolar content in the neurohypophysis. In addition, there were extensive oedematous areas and vascular congestions caused by necrotic cells in both the adenohypophysis and neurohypophysis (Figure 1c and d, Table 2, HHS: 6(6-7)). On examination of the pituitary tissue sections of the dexmedetomidine treatment group under a light microscope, we observed necrotic chromophobic, chromophilic cells in adenohypophysis tissue and cells with fewer necrotic pituicytes in neurohypophysis tissue. We also determined a reduction in oedematous areas and vascular congestion in both the adenohypophysis and neurohypophysis (Figure 1e and f, Table 2, HHS: 2(1-2)).
Pituitary hyperplasia mimicking thyrotropin-producing pituitary adenoma in the patient with resistance to thyroid hormone: a case report
Published in International Journal of Neuroscience, 2021
Onnicha Suntornlohanakul, Chutintorn Sriphrapradang
Pituitary hyperplasia or enlargement is one of the frequent etiologies of pituitary incidentaloma [11]. The normal pituitary height should not be exceed 9 mm [12]. The MRI findings in pituitary hyperplasia include symmetrical pituitary enlargement with smooth contours, central upward convexity, and normal neurohypophysis signals. Dynamic studies showed homogenous contrast enhancement [13]. The increase in pituitary size may be followed by physiologic and pathologic conditions [6]. Physiologic pituitary hyperplasia is common during puberty, pregnancy, and postmenopausal period. High estrogen levels during pregnancy result in lactotroph hyperplasia, with largest enlargement noted in the first few days postpartum. The pituitary usually returns to normal size within the first 6 months following delivery. Pathologic pituitary hyperplasia has been reported in severe primary hypothyroidism or excess of growth hormone-releasing hormone or corticotrophin-releasing hormone [6]. In our patient, she had a history of abortion that may be the physiologic cause of pituitary hyperplasia. However, the pituitary hyperplasia did not resolve after abortion 9 months. This should be suggested that pituitary hyperplasia may be caused by other reasons.