Hormones and Related Drugs

HORMONES AND RELATED DRUGS

Hormone (Greek hormaein—to stir up) is a substance of intense biological activity that is produced by specific cells in the body and is transported through circulation to act on its target cells.

Hormones regulate body functions to bring about a programmed pattern of life events and maintain homeostasis in the face of markedly variable external/internal environment.

Hormones are secreted by the endocrine or ductless glands. These are:

1. Pituitary

a)    Anterior

Growth hormone (GH), Prolactin (Prl),

Adrenocorticotropic hormone (ACTH, Corticotropin),

Thyroid stimulating hormone (TSH, Thyrotropin),

Gonadotropins—Follicle stimulating hormone (FSH) and Luteinizing hormone (LH).

b)    Posterior—Oxytocin,

Antidiuretic hormone (ADH, Vasopressin).

2. Thyroid Thyroxine (T₄), Triiodothyronine (T₃), Calcitonin.

3. Parathyroid  Parathormone (PTH).

4. Pancreas (Islets of Langerhans) Insulin, Glucagon.

5. Adrenals

a)    Cortex

Glucocorticoids (hydrocortisone) Mineralocorticoids (aldosterone) Sex steroids (dehydroepiandrosterone)

b)    Medulla 

Adrenaline, Noradrenaline

6. Gonads

    Androgens (testosterone) Estrogens (estradiol) Progestins (progesterone)

In addition, hypothalamus, which is a part of the CNS and not a gland, produces many releasing and inhibitory hormones which control the secretion of anterior pituitary hormones. Some important ones of these are given below

Placenta also secretes many hormones:

Chorionic gonadotropin

Prolactin

Estrogens                  

Progesterone

Placental lactogen     

Chorionic thyrotropin

The natural hormones and in many cases their synthetic analogues which may be more suitable therapeutically, are used as drugs for substitution therapy as well as for pharmaco-therapy. In addition, hormone antagonists and synthesis/ release inhibitors are of therapeutic importance.

Sites And Mechanisms Of Hormone Action

The hormones act on their specific receptors located on or within their target cells. Receptor activation by the hormones is translated into response in a variety of ways.