Caffeine/Coffee

* actually seeds: 2 per berry, Coffea arabica * each bean 0.8 - 2.5% caffeine * also, 0.6% cafestol (anticarcinogenic): fillers remove it

* Emperor of China: Tea * coffee * roasted * Persia, Turkey, N. Africa * "caffe" (1598 English derivation "coffee") * declared it a "Christian beverage" * European coffee house (Italy) * tea imports banned, coffee grew in popularity in U.S. * 80-90% of adults caffeinated beverages (average 2-400 mg per day) * colder climates (Sweden, Norway, Netherlands)

* orally * 30-60 min * 4 hrs; 10 hrs * cytochrome P450 1A2 * dimethylxanthines 1) Paraxanthine (84%) 2) Theobromine (12%) 3) Theophyllines (4%)

Beverages, chocolate, analgesic drugs, over-the-counter stimulants

1) Phosphodiesterase inhibitor (high dose): enzymes break down cAMP, so build up of cAMP in brain mediates stimulatory behavior 2) stimulation of intracellular Ca2+ release (high dose) 3) GABA_A blocker (high dose) 4) adenosine receptor blocker

adenosine receptor blocker (A₁ and A_2A), the other ones require very high doses

Acts like a NT in the extracellular fluid in basal forebrain: elevated during prolonged wakefulness * responsible for drowsiness that occurs after period of sleep deprivation

A₁ and A_2A (thought to mediate most of the behavioral effects of caffeine in lab animals)

Metabotropic prolonged wakefulness -> drowsiness sleepiness A₁, A_2A, A_2B, A₃

Rodents: low doses=stimulatory, high doses=opposite humans: low=stimulant, reduces fatigue; high=tension and anxiety * in patients with panic disorder, induces panic attack

Feelings of well-being, enhanced energy, increased alertness, concentration, self-confidence, motivation, sociability

Blood pressure, respiration, water excretion, catecholamine release (norepinephrine)

* minor analgesic, increases efficacy if acetaminophen or aspirin * helps newborns with apnea (breathing cessation)

* regular user will have no insomnia if he/she drinks it at night * reduced cardiovascular and respiratory effects

Headache, drowsiness, fatigue, craving; sometimes anxiety or depression * in light consumers (1 c. coffee per day or 3 cans of soda; children experience withdrawal)