Habenular signaling in nicotine reinforcement

Ganglionic stimulants activate NM nicotinic receptors in autonomic ganglia, falling into two categories: nicotine mimetics [e.g., lobeline, dimethylpiperazine, tetramethylammonium] and muscarinic receptor agonists [e.g., muscarine, methacholine]. The first category's action is rapid and blocked by nicotinic receptor antagonists, while the second category's action is delayed and blocked by atropine-like agents. Nicotine, an alkaloid, affects the heart rate by stimulating sympathetic or...

Nicotinic receptors are ligand-gated ion channels that are activated by acetylcholine and nicotine. Upon activation, they cause a rapid increase in the permeability of cells to K+, Na+, and Ca2+, followed by depolarization and excitation. They are in the autonomic ganglia, skeletal neuromuscular junction, CNS, and adrenal medulla.
There are two types of nicotinic receptors: neuromuscular (NM/NM/N1) and neuronal (NN/NN/N2). The two families differ based on their location and selectivity to...

Sympathetic signaling, a vital part of the autonomic nervous system, plays a crucial role in mobilizing the body's resources in response to stress or emergencies. It involves the transmission of nerve impulses from sympathetic preganglionic fibers to postganglionic fibers. This results in the release of specific neurotransmitters and activation of adrenergic receptors.
Sympathetic preganglionic fibers release the neurotransmitter acetylcholine (ACh) onto the ganglionic neurons in the...

Parasympathetic signaling plays a crucial role in regulating various physiological processes. It involves the release of acetylcholine (ACh) by parasympathetic neurons, which can have localized and short-lived effects. The majority of ACh released is rapidly inactivated at the synapse by the enzyme acetylcholinesterase (AChE), which hydrolyzes Ach into choline and acetate. Additionally, the tissue cholinesterase deactivates any ACh diffusing into the surrounding tissues.
The effects of...

Short-term regulation of food intake primarily involves neural signals from the gastrointestinal (GI) tract, blood nutrient levels, and GI tract hormones. Communication between the gut and brain via vagal nerve fibers plays a significant role in evaluating the contents of the gut. Clinical studies have shown that protein ingestion produces a more prolonged response in these nerve fibers compared to an equivalent amount of glucose. Additionally, the activation of stretch receptors caused by GI...

Ethanol, a clear colorless alcohol, has been consumed by humans for millennia, but its effects on the body are far from benign. At lower doses, it induces decreased inhibitions and loquaciousness, leading to its social appeal. However, it can cause severe consequences at higher doses, such as coma and respiratory depression, due to its zero-order elimination kinetics. Chronic ethanol abuse wreaks havoc on multiple organ systems, particularly the CNS and the liver. Abrupt cessation of ethanol...