Pituitary Gland Research Paper

INTRODUCTION The pituitary gland is a central endocrine organ that regulates basic physiological functions incuding growth, reproduction and metabolic homeostasis. It situates at the base of the brain, under the optic chiasm, inside a depression on the upper surface of the sphenoid bone, the sella turcica1 (Fig.1). Fig. 1 The pituitary is a small gland found inside the skull just below the brain and above the nasal passages, which are above the fleshy back part of the roof of the mouth (known as the soft palate). The pituitary sits in a tiny bony space called the sella turcica. The nerves that connect the eyes to the brain, called the optic nerves, pass close by it.

Is a small neuro-endocrine organ with a diameter of only 1 centimetre,

The anterior pituitary is devoid of a nerve supply, but has a unique blood supply, a portal system. The hypothalamohypophyseal portal system begins in a series of capillaries in the median eminence of the hypothalamus sends blood via veins to the anterior lobe, where it ends in a series of capillaries. This portal system carries neurohormones from the hypothalamus to the anterior pituitary where they control the secretion of anterior lobe hormones.

The anterior pituitary consists of five different endocrine cell types, identified by antibodies against pituitary hormones and capable of production and secretion of pituitary hormones:

1. Somatotroph cells. These cells are acidophilic and produce growth hormone (GH).

2. Lactotroph cells. These cells are acidophilic and produce prolactin.

3. Corticotroph cells. These cells are basophilic and produce adenocorticotrophic hormone (ACTH), pro-opiomelanocortin (POMC), melanocyte stimulating hormone (MSH) and

Molecular genetics have shown nearly all to be monoclonal, suggesting that an intrinsic pituitary defect is likely to be responsible for pituitary tumorigenesis. Occasionally, prolactinoma may be part of a multiple endocrine neoplasia syndrome (MEN-1), but this occurs too infrequently to justify MEN-1 screening in every patient with a prolactinoma.

• GH- and PRL-secreting adenomas (or mammosomatotroph adenomas)

Mixed growth hormone (GH)- and PRL-secreting tumors are well recognized and give rise to acromegaly in association with hyperprolactinemia. Malignant prolactinomas are rare. A few cases have been described that have proved resistant to aggressive treatment with surgery, radiotherapy, dopamine agonists, and, occasionally, chemotherapy. In a small proportion, extracranial metastases in liver, lungs, bone, and lymph nodes have been documented.

• ACTH-secreting adenomas (or corticotropinomas). ACTH stimulates the adrenal gland to make glucocorticoids (or steroids, which influence metabolism and act as anti-inflammatory and immunosuppressive agents). An oversupply of ACTH, such as that produced by this type of tumor, can cause Cushing's disease (one type of Cushing's