Hormones

Hormones are a diverse class of regulatory signaling molecules produced by specialized glands and cells within the endocrine system, which are secreted into the bloodstream to modulate the physiological activity of distant target organs [1]. They are broadly categorized into three chemical groups: peptides (e.g., insulin and growth hormone), steroids (e.g., estrogen and cortisol), and amino acid derivatives (e.g., thyroxine and epinephrine) [2]. Each hormone exerts its specific biological effects by binding to high-affinity receptors, which may be located on the plasma membrane or within the nucleus of target cells, thereby initiating intracellular signaling cascades or direct transcriptional changes [3]. Clinical pathology often arises from the hypersecretion, hyposecretion, or impaired sensitivity to these molecules, leading to conditions such as diabetes, Graves' disease, or Addison's disease [4]. In pharmacology, hormones are frequently used as replacement therapies for deficiencies or as tools to manipulate physiological processes, such as in contraception or cancer treatment [5]. Because the term "Hormones" refers to a large and varied functional class of molecules rather than a specific protein, receptor, or enzyme, it is classified as a general category rather than a single therapeutic target [1][2].

Other names

Endocrine factorsChemical messengersSignaling moleculesHumoral factors

Hormones function as ligands that bind to specific cell-surface receptors (e.g., GPCRs, receptor tyrosine kinases) or intracellular receptors (e.g., nuclear receptors) to modulate gene expression and enzymatic activity; therapeutic strategies involve hormone replacement, receptor agonism/antagonism, or inhibition of hormone synthesis.