Far from the heart: Receptor cross-talk in remote conditioning

Classical conditioning not only includes the initial pairing of stimuli but also extends to more complex forms, such as higher-order conditioning. Higher-order conditioning involves creating associations beyond the primary conditioned stimulus, resulting in a chain of conditioned responses.
Higher-order, or second-order, conditioning occurs when a neutral stimulus becomes associated with an already established conditioned stimulus through repeated pairings. For instance, if a dog has been...

Classical conditioning, as described by Ivan Pavlov, is a foundational concept in associative learning, where a neutral stimulus becomes capable of eliciting a conditioned response through association with an unconditioned stimulus. The process of acquisition, where this learning occurs, and the subsequent phenomena of contiguity, contingency, generalization, discrimination, extinction, and spontaneous recovery are crucial for a comprehensive understanding of classical conditioning.
During the...

GPCRs are primarily responsible for our sense of smell, taste, and vision.  The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory organs,...

Some receptors remain unoccupied even when an agonist produces a maximal response. Such empty ones are called spare receptors. In presence of spare receptors the maximum effect of an agonist drug is achieved with fewer than 100% of the receptors being occupied. To determine the presence of spare receptors, scientists often compare the concentration of the drug needed to produce 50% of the maximum effect (EC50) with the concentration of the drug needed to occupy 50% of the receptors (Kd). If the...

Classical conditioning, a fundamental principle of associative learning, explains various phenomena observed in daily life, such as fear development, the placebo effect, taste aversion, and drug habituation. These applications demonstrate the profound impact of associative learning on human behavior and physiological responses.
John B. Watson and Rosalie Rayner famously demonstrated the development of fear through classical conditioning in their experiment with Little Albert. They paired the...

Tachyphylaxis is described as a rapid decrease in response to a drug after repeated or continuous administration of the same drug dose. It is a phenomenon where the body becomes less responsive to a particular substance or intervention over time, requiring higher doses or stronger interventions to achieve the same effect. It results from adaptive changes in the body's receptors, signaling pathways, or physiological processes that occur in response to prolonged exposure to a stimulus.
Several...