Biomaterial Database

Electrophysiological evidence for nicotinic and muscarinic modulation of spinal cord reflexes. 1989

N A Ibrahim, and B D Goldstein

Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta 30912.

Intravenous administration of physostigmine has been found to produce dose- and time-dependent alterations of the lumbar monosynaptic and polysynaptic reflexes in spinal cats. A small dose of physostigmine (0.8 mg/kg) enhanced the monosynaptic reflex for 3 hr, while a larger dose (2.0 mg/kg) produced a pattern of initial depression which peaked at 5 min, followed by an increase which was maintained for 3 hr after injection. Both doses of physostigmine were found to produce a similar pattern of enhancement of the polysynaptic reflex. Atropine and mecamylamine antagonized the increase of the monosynaptic reflex produced by both doses of physostigmine. The initial depression of the monosynaptic reflex produced by the large dose of physostigmine was blocked by mecamylamine, but unaffected by atropine. The enhancement of the polysynaptic reflex, produced by both doses of physostigmine, was antagonized by atropine but not by mecamylamine. In addition, nicotine and oxotremorine were found to mimic the initial effects of physostigmine in the presence of the appropriate antagonist. These data show that both muscarinic and nicotinic receptors are involved differentially in the modulation of spinal reflexes and that physostigmine had an additional late effect which consistently occurred at 20 min after administration.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008464	Mecamylamine	A nicotinic antagonist that is well absorbed from the gastrointestinal tract and crosses the blood-brain barrier. Mecamylamine has been used as a ganglionic blocker in treating hypertension, but, like most ganglionic blockers, is more often used now as a research tool.
D009538	Nicotine	Nicotine is highly toxic alkaloid. It is the prototypical agonist at nicotinic cholinergic receptors where it dramatically stimulates neurons and ultimately blocks synaptic transmission. Nicotine is also important medically because of its presence in tobacco smoke.	Nicotine Bitartrate,Nicotine Tartrate
D010095	Oxotremorine	A non-hydrolyzed muscarinic agonist used as a research tool.	Oxytremorine
D010276	Parasympatholytics	Agents that inhibit the actions of the parasympathetic nervous system. The major group of drugs used therapeutically for this purpose is the MUSCARINIC ANTAGONISTS.	Antispasmodic,Antispasmodic Agent,Antispasmodic Drug,Antispasmodics,Parasympathetic-Blocking Agent,Parasympathetic-Blocking Agents,Parasympatholytic,Parasympatholytic Agent,Parasympatholytic Drug,Spasmolytic,Spasmolytics,Antispasmodic Agents,Antispasmodic Drugs,Antispasmodic Effect,Antispasmodic Effects,Parasympatholytic Agents,Parasympatholytic Drugs,Parasympatholytic Effect,Parasympatholytic Effects,Agent, Antispasmodic,Agent, Parasympathetic-Blocking,Agent, Parasympatholytic,Agents, Antispasmodic,Agents, Parasympathetic-Blocking,Agents, Parasympatholytic,Drug, Antispasmodic,Drug, Parasympatholytic,Drugs, Antispasmodic,Drugs, Parasympatholytic,Effect, Antispasmodic,Effect, Parasympatholytic,Effects, Antispasmodic,Effects, Parasympatholytic,Parasympathetic Blocking Agent,Parasympathetic Blocking Agents
D010830	Physostigmine	A cholinesterase inhibitor that is rapidly absorbed through membranes. It can be applied topically to the conjunctiva. It also can cross the blood-brain barrier and is used when central nervous system effects are desired, as in the treatment of severe anticholinergic toxicity.	Eserine
D011976	Receptors, Muscarinic	One of the two major classes of cholinergic receptors. Muscarinic receptors were originally defined by their preference for MUSCARINE over NICOTINE. There are several subtypes (usually M1, M2, M3....) that are characterized by their cellular actions, pharmacology, and molecular biology.	Muscarinic Acetylcholine Receptors,Muscarinic Receptors,Muscarinic Acetylcholine Receptor,Muscarinic Receptor,Acetylcholine Receptor, Muscarinic,Acetylcholine Receptors, Muscarinic,Receptor, Muscarinic,Receptor, Muscarinic Acetylcholine,Receptors, Muscarinic Acetylcholine
D011978	Receptors, Nicotinic	One of the two major classes of cholinergic receptors. Nicotinic receptors were originally distinguished by their preference for NICOTINE over MUSCARINE. They are generally divided into muscle-type and neuronal-type (previously ganglionic) based on pharmacology, and subunit composition of the receptors.	Nicotinic Acetylcholine Receptors,Nicotinic Receptors,Nicotinic Acetylcholine Receptor,Nicotinic Receptor,Acetylcholine Receptor, Nicotinic,Acetylcholine Receptors, Nicotinic,Receptor, Nicotinic,Receptor, Nicotinic Acetylcholine,Receptors, Nicotinic Acetylcholine
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D012023	Reflex, Monosynaptic	A reflex in which the AFFERENT NEURONS synapse directly on the EFFERENT NEURONS, without any INTERCALATED NEURONS. (Lockard, Desk Reference for Neuroscience, 2nd ed.)	Monosynaptic Reflex