Download presentation
1
Plant Drugs that Affect the Autonomic Nervous System
2
Major Divisions of the Nervous System
Central nervous system (CNS) brain and spinal column Peripheral nervous system (PNS) somatic nervous system: innervates skeletal muscle during voluntary movement (efferent system) & sensory nerve endings for touch and pain (afferent system) Autonomic nervous system (ANS): controls involuntary responses that maintain homeostasis
3
Major Divisions of the Autonomic Nervous System
Sympathetic Nervous System & Parasympathetic Nervous System the two systems work antagonistically: inhibition of one system tends to produce effects that resemble the stimulation of the other system
5
Sympathetic Nervous System
Catabolic system that expends (burns) energy Nerves in this system originate from the thoraco-lumbar regions “Fight or flight” responses to danger: increase in heart rate & force of ventricular contractions shunting blood to muscles and heart increase in sweat gland secretion dilates pupils dilates bronchial tubes inhibits GI motility and secretions, contracts GI sphincters stimulates secretion of adrenaline from adrenal medulla
6
Parasympathetic Nervous System
Anabolic system that promotes the conservation and storage of energy Nerves in this system originate from the cranial and sacral regions promotes digestion and storage of food contracts pupils stimulates secretion from lacrimal and salivary glands decreases heart rate and force of ventricular contractions constricts bronchia and stimulates bronchial gland secretion stimulates motility and secretion of GI tract relaxes GI sphincters contracts bladder
8
Peripheral (Efferent) Nervous System: Neurotransmitters & Receptors
CNS Sympathetic adrenergic receptor nicotinic receptor Parasympathetic muscarinic receptor Somatic Motor nicotinic receptor nicotinic and muscarinic receptors = cholinergic receptors
9
Sympathetic Nervous System Adrenergic Receptors (Stimulated by Endogenous Norepinephrine)
alpha receptors – reduce glandular secretions, GI motility, increase constriction of certain arterioles and veins beta receptors – increase heart rate, contractions, increase kidney renin secretion, relax trachea and bronchioles, dilate some arterioles and veins (not in skin or brain), increase breakdown of fats to release energy Epinephrine (adrenaline) – main neurohormone produced by the adrenal medulla – the most potent endogenous stimulator of adrenergic alpha and beta receptors
10
Parasympathetic Nervous System Receptors (Stimulated by Endogenous Acetylcholine)
Nicotinic receptors – are located in the autonomic ganglia of both the sympathetic and parasympathetic systems (and the nerve endings of the somatic motor system)
11
Parasympathetic Nervous System Receptors (Stimulated by Endogenous Acetylcholine)
Muscarinic receptors - are associated with parasympathetic functions and are located at the ends of postganglionic neurons in peripheral tissues (effectors, e.g., glands, smooth muscle) innervated by the parasympathetic system
12
Parasympathetic Nervous System Receptors (Stimulated by Acetylcholine)
Nicotinic receptor - a channel protein that, upon binding by acetylcholine, opens to allow diffusion of cations Muscarinic receptor - a membrane protein: upon stimulation by neurotransmitter, it causes the opening of ion channels indirectly, through a second messenger. For this reason, the action of a muscarinic synapse is relatively slow.
13
Drugs that affect the autonomic nervous system:
agonists – substances that stimulate receptors antagonists – substances that block a receptor drugs that have chemical or molecular resemblance to endogenous neurotransmitters (acetylcholine or norepinephrine) of the ANS can stimulate or inhibit this system
14
Parasympathetic Agonists
Modes of action: direct agonistic action on the receptor inactivation of acetylcholinesterase (enzyme that breaks down acetylcholine), resulting in accumulation of acetylcholine in synaptic cleft
15
Muscarinic Cholinergic Receptor Agonists
Acetylcholine (endogenous neurotransmitter) Synthetic choline esters (methacholine, carbachol, betanechol) Cholinomimetic plant (and fungal) alkaloids: muscarine pilocarpine arecoline (also affects nicotinic cholinergic receptors)
16
Muscarine compound isolated from various species of fungi:
Amanita muscaria, Amanita spp., Inocybe spp. and Clitocybe spp. common name: amanita, fly agaric origin: Siberia, North America habit: mushroom with red, orange, yellow or cream colored cap with white spots. Grows on forest floor
18
Muscarine, cont. Ethnomedical/cultural uses:
mushroom eaten by Siberian indigenous people as hallucinogen dried mushrooms repel flies compounds with hallucinogenic (CNS) activity: ibotenic acid, muscimole, muscazone PSN principle active compound: muscarine
19
Muscarine, cont. chemical class: quaternary ammonium alkaloid
chemical derivatives: muscarine oxotremorine Muscarine effects: diaphoretic, salivation, lacrimation, vision problems, nausea, vomiting, diarrhea, hypotension, brachycardia, bronchiospasm Oxotremorine effects: stimulates receptors in basal ganglia and produces parkinsons-like effects (spasticity or tremor) Modern medical uses: neurobiological research (understanding muscarinic receptors) Antedote: 1 – 2 mg of atropine IM every 30 min
20
Pilocarpine Isolated from Pilocarpus jaborandi, P. microphyllus
Plant family: Rutaceae (citrus family) Common name: Jaborandi (means slobber mouth plant in Tupi language) Origin: lowland wet forests of Tropical America, West Indies Ethnomedical uses: members of the Tupi culture in Brazil chew leaves to induce salivation and sweating
22
Pilocarpine, cont. Chemical class: tertiary amine alkaloid
Mechanism of action: cholinergic receptor agonist with strong postganglionic (muscarinic receptor) stimulation and mild ganglionic (nicotinic receptor) stimulation Muscarinic receptor stimulation effects: salivation intestinal motility pupil constriction
23
Pilocarpine, cont. Therapeutic uses:
Topical application to eye constricts pupils treats open-angle glaucoma by reducing intraocular pressure Oral administration treats dry mouth (xerostoma) Also used to reduce side effects of morphine treatment, including: dry mouth constipation urinary retention Overdose may cause cardiovascular collapse Antedote is atropine (conversely, pilocarpine is sometimes used as an antedote in cases of atropine poisoning)
24
Arecoline From Areca catechu Plant family: Arecaceae (palm family)
Common name: betelnut, betel, areca nut Origin: tree in wet forests of S Asia, Indomalaysia, Oceania, probably originally from Sulawesi (Indonesia) Ethnobotanical use: Used as a masticatory (chew): the areca seed is rolled in leaves of Piper betel and mixed with gambir (a spice made from the boiled leaves of Unicaria gambir) and shell lime (which changes pH to release active compounds)
26
Arecoline, cont. Ethnomedical uses:
euphoretic cardiac tonic energizer antihelminthic Chemical structure: arecoline is an alkaloid Chemical derivative: arecoline aceclidine (glaucoma treatment in Europe) Arecoline stimulates both muscarinic and nicotinic receptors (in ANS and CNS)
27
Parasympathetic Agonists: Anticholinesterase Compounds
prevent hydrolysis of acetylcholine by acetylcholinesterase at cholinergic transmission sites, resulting in an accumulation of the transmitter some synthetic compounds with this type of activity include: insecticides (parathion, malathion) nerve poisons (sarin, tabun)
28
Physostigmine From Physostigma venemosum
Plant family: Fabaceae (pea or bean family) Common names: calabar, ordeal, or esere bean Origin: rainforests of West Africa Habit: a perennial woody vine (liana) Cultural origins: used by the Efik people of the Calabar region of SE Nigeria
30
Physostigmine, cont. Ethnomedical uses:
dry beans as ordeal poison in witchcraft trials perceived ability to “reveal” and “destroy” witchcraft…suspected witch is given a drink of ground up beans in water: if guilty, mouth shakes and mucous comes out of nose (and/or the person dies), if innocent, the suspect will only vomit beans still carried today for protection against witchcraft
31
Physostigmine, cont. Chemical class: indole alkaloid
Chemical derivatives: neostigmine pyridostigmine edrophonium demecarium
32
Physostigmine, cont. Mechanism of action:
inhibits acetylcholinesterase in postganglionic nerves & myoneural nerve endings (somatic motor neurons) Physiological cholinergic effects: diaphoresis (sweating) reduced heart rate smooth muscle stimulation in intestines and bladder
33
Physostigmine, cont. Modern medical uses of physostigmine and derivatives – Physostigmine: glaucoma antedone for anticholinergic (e.g., atropine) poisoning Neostigmine, pyridostigmine, demercarium: intestinal stimulant treatment of myasthenia gravis (muscle weakness disease with defect in myoneural conduction) Edrophonium: used to diagnose and treat myasthenia gravis
35
Intermission
36
Peripheral Nervous System: Neurotransmitters & Receptors
CNS Sympathetic adrenergic receptor nicotinic receptor Parasympathetic muscarinic receptor Somatic Motor nicotinic receptor nicotinic and muscarinic receptors = cholinergic receptors
37
Antimuscarinic (Anticholinergic) Compounds
Parasympathetic depressants – substances that are muscarinic receptor antagonists The plant family Solanaceae is the major natural source of antimuscarinic compounds Tropane alkaloids
38
Solanaceae
40
Antimuscarinic (Anticholinergic) Compounds
Tropane alkaloids from the Solanaceae: atropine scopolamine hyoscyamine
41
Antimuscarinic (Anticholinergic) Compounds
Tropane Alkaloids: Resemble chemical structure of acetylcholine, but act as antagonists at receptor Bind to postganglionic parasympathetic receptors and block access of acetylcholine Interfere or block the normal transmission of postganglionic parasympathetic messages Also can have a CNS effect (especially scopolamine) Synthetic muscarinic receptor antagonists include tricyclic antidepressants
42
Atropa belladona
43
Atropa belladonna Common name: belladonna
historically used as a cosmetic to enlarge pupils also used to poison various Roman emperors Origin: Europe Also traditionally used as an: analgesic intestinal antispasmodic hallucinogen (a component of witches “flying ointment” in the Middle Ages in Europe)
44
Atropa belladonna Active compounds: atropine (first isolated in 1831)
anticholinergic at muscarinic receptors pupil dilator (mydriatic) cardiac stimulant Hyoscyamine analgesic antispasmodic Scopolamine anticholinergic and has CNS effects pupil dilator hallucinogen
45
Atropa belladonna Therapeutic uses of belladonna and its tropane alkaloids: A. belladonna tincture: used as an intestinal antispasmodic and analgesic Scopolamine: used to dilate pupils, used to treat motion sickness (unfortunate side effect of hallucinations) Hyoscyamine: used as an analgesic, sedative, and antispasmodic Atropine: used as a pupil dilator, cardiac stimulant, treatment for brachycardia, treatment for organophosphate or insecticide poisoning (counteracts effects of muscarinic agonists) Lomotil (atropine-diphenoxylate): reduces intestinal motility to treat diarrhea Atrovent (ipatropium bromide): a bronchodilator used to treat asthma
46
Hyoscyamus niger & H. muticus
47
Hyoscyamus niger & H. muticus
Common name: Henbane Hyoscyamus niger: from Eurasia, N. Africa Hyoscyamus muticus: from India to Egypt, grown in CA Habit: herbaceous plant in open fields and disturbed areas Plant parts used: leaves, flower tops (rich in hyoscyamine) leaves seeds (rich in scopolamine)
48
Hyoscyamus niger & H. muticus
Ethnomedical uses: used in many cultures in Europe, Egypt, Near East and Asia as an: antispasmodic analgesic mydriatic (pupil dilator) inebriant / hallucinogen
49
Hyoscyamus niger & H. muticus
Active compounds: hyoscyamine anticholinergic at muscarinic receptors analgesic, sedative, intestinal antispasmodic scopolamine anticholinergic, also CNS effects pupil dilator and treatment for motion sickness
50
Mandragora officinarum
51
Mandragora officinarum
Common name: Mandrake Origin: Europe to the Himalayas Habit: herb with thick tuberous roots that sometimes resemble a human Cultural origins: used by many cultures in Europe and Asia
52
Mandragora officinarum
53
Mandragora officinarum
“The root was to be picked before dawn on a Friday morning by a black dog, then washed and "fed" with milk and honey and, in some prescriptions, blood, whereupon it would fully develop into a miniature human which would guard and protect its owner.”
54
Mandragora officinarum
All parts of plant contain hyoscyamine Therapeutic uses: intestinal antispasmodic analgesic sedative used as an anesthetic in surgery until the introduction of ether in the mid 1800s
55
Datura stramonium
56
Datura stramonium Common names:
Algonquin: wysoccan English: Jimson weed, Jamestown weed, thorn apple Origin: North America, now naturalized around the world Habit: herb with erect flowers that grows in open fields and disturbed areas
57
Datura stramonium Ethnomedical uses: leaves, fruits taken orally for:
asthma sedative hallucinogen (esp. the seeds) Algonquins of the eastern US gave wysoccan to boys as a hallucinogen for days in adolescent ceremony…after completion of ceremony, they were considered adults
59
Datura stramonium Active compounds: Scopolamine Hyoscyamine
Therapeutic uses: pupil dilation, antispasmodic, analgesic
60
other Datura species Ethnomedical uses: sacred psychogenic & hallucinogen D. innoxia – sacred hallucinogen in SW US and Mexico D. ceratocaula – used by Aztecs D. candida – Colombia & South America D. metel – native to India, used by Hindu sadhus for spiritual experience…this painting sometimes present in paintings of Shiva
61
Datura innoxia – US Southwest & Mexico
62
Datura ceratocaula – Central America
63
Datura candida – Colombia, South America
64
Datura metel - India
65
Datura metel - India
66
Brugmansia spp. Common name: trumpet flower
Perennial shrubs and trees with pendulous flowers Chemistry: tropane alkaloids, especially scopolamine Ethnomedical uses: sacred psychoactive with intense intoxication followed by hallucinations
67
Brugmansia spp. Brugmansia aurea – different varieties with different hallucinogenic properties are propagated vegetatively by shamans in South America
68
Brugmansia aurea
69
Brugmansia spp. Brugmansia sanguinea – used as a hallucinogen and medicine by South American cultures from Chile to Colombia
70
Brugmansia sanguinea
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.