NeuroEndocrinology

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Neuroendocrinology

What is NeuroEndocrinology?

Neuro means the study of the brain and nervous system. Endocrinology means the study of hormones. So therefore, Neuroendocrinology is the study of the interactions between hormones and the brain (which amounts to basically how hormones affect behaviors). This also includes the biological features of the cells involved and how they communicate.

Hormones are basically chemical messengers that transport signals from one cell to another within the body. When hormone levels are abnormal or off, signs of abnormal behavior and illness will develop (for example: mood or behavior changes, weight gain, seizures, and/or depression).

Neuroendocrinology includes the other things that the brain regulates, such as the autonomic nervous system, and even the immune system – or immune system hormones anyway.

What does Neuroendocrinology include?

Neuroendocrinology combines elements from different fields, including OB/GYN, psychiatry, endocrinology and behavioral neurology. Doctors in these specialties often refer cases to a Neuroendocrinologist to help sort out hormonal issues.

What Is Neuroendocrine Integration?

The nervous and endocrine systems often act together in a process called neuroendocrine integration, to regulate the physiological processes of the human body. Neuroendocrinology arose from the recognition that the brain, especially the hypothalamus, controls secretion of pituitary gland hormones, and has subsequently expanded to investigate numerous interconnections of the endocrine and nervous systems.

The neuroendocrine system is the mechanism by which the hypothalamus maintains homeostasis, regulating reproduction, metabolism, eating and drinking behaviour, energy utilization, osmolarity and blood pressure.

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs.

How are Neuroendocrinology and Traumatic Brain Injury (TBI) Linked?

The greatest challenge associated with endocrine complications in individuals with traumatic brain injury (TBI) is early recognition of these subtle problems. Often times emergency room personnel are focused on life threatening areas of the body including the airway, breathing, and maintaining adequate circulation, and stabilizing life threatening issues.  The primary thought at this time does not include a protocol for running laboratory tests for Endocrine issues/changes due to potential brain injuries in any form.

Endocrine complications can produce significant impact on the progress and outcome of TBI rehabilitation, they can even enhance the duration of TBI symptoms in recovery. Prompt diagnosis and treatment of endocrine complications following TBI facilitate the rehabilitation process of patients with TBI.

Anterior pituitary hormones (eg, growth hormone [GH],thyrotropin, corticotropin, gonadotropins) are released by the neuropeptide-releasing hormones from the hypothalamus. The posterior pituitary hormones (eg, vasopressin, oxytocin) are produced by the hypothalamus and are carried by long axonal projections into the posterior pituitary; they are released later. The posterior lobe vascular supply is not affected by pituitary stalk trauma, because it is supplied by the inferior hypophyseal arteries, which arise from the internal carotid artery below the level of the diaphragma sella.

The most common endocrine complication after a TBI is syndrome of inappropriate antidiuretic hormone (SIADH). SIADH causes a dilutional hyponatremia secondary to inappropriate renal water conservation. Relatively less common post-TBI endocrinopathies include anterior hypopituitarism (AH), DI, cerebral salt wasting (CSW), and primary adrenal insufficiency (PAI).

The most common endocrinopathies associated with hypopituitarism, in descending order, include hypogonadism, hypothyroidism, adrenal insufficiency, hyperprolactinemia, DI, and GH deficiency. CSW and PAI are peripheral causes of hyponatremia after a TBI. SIADH, AH, and DI have central endocrine etiologies.

A retrospective study demonstrated that 4% of patients with TBI sustained an associated neuroendocrine disorder of the hypothalamic-pituitary axis. This condition is underdiagnosed, as demonstrated by evidence that 40-63% of fatal cases of TBI reveal postmortem pathologic findings of the hypothalamus/anterior pituitary.

CLINICAL PRESENTATIONS

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