Related Experiment Video
Updated: Aug 15, 2026

Ex Vivo Calcium Imaging for Visualizing Brain Responses to Endocrine Signaling in Drosophila
Published on: June 2, 2018
Abstract:
Hormones act via receptors, i.e. structures which contain specific binding sites for any given hormone. The transmission of information is accomplished by reversible binding of the hormone to the receptor. Steroid hormones and triiodothyronine act via receptors which are located in the nucleus and regulate the biosynthesis of specific proteins. Peptide hormones and catecholamines combine with receptors within the cell membrane, thereby regulating the membrane-bound enzyme adenyle cyclase. The product of this enzyme, cyclic AMP, acts as a transmitter of the action of these hormones in the interior of the cell.
Related Concept Videos
Types of Hormones
Chemical Signaling in the Endocrine System
Lipid-soluble hormones, such as steroid hormones, demonstrate an intracellular action. These hormones traverse cell membranes due to their lipid nature. Once inside the target cell, they...
Types of Hormones
Steroids and eicosanoids fall under the category of lipid-soluble hormones. Steroids are derived from cholesterol and feature four interconnected carbon rings with variable side chains. Notable examples include estradiol from ovaries and testosterone from testes, exemplifying the critical roles of these lipid-soluble hormones in reproductive physiology. Eicosanoids, derived...
Secondary Messengers in Hormone Action
Many hormones bind to transmembrane G protein-coupled receptors that connect to regulatory G proteins. These G proteins can then activate enzymes such as adenylyl cyclase or phospholipase C. Adenylyl cyclase converts ATP to cAMP, activating...
Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
Regulation of Hormone Secretion
Humoral stimuli,...

