Pineal stimulation produces both hypertension and tachycardia in rats.
In anesthetized rats, electrical stimulation of pineal gland elicited proportional hypertension and tachycardia, which could be mimicked by microinjection of an excitatory amino acid, kainic acid (0.3 micrograms), into the pineal gland. The hypertension induced by pineal stimulation was antagonized by either spinal transection or postsynaptic blockade of serotonin receptors, while the tachycardia induced by pineal stimulation was antagonized by either serotonin receptor antagonism, bilateral vagotomy or spinal transection. In addition, postsynaptic blockade of serotonin receptors with cyproheptadine (2-5 mg/Kg, IV) produced both hypotension and bradycardia, while stimulation of 5-HT receptors with DOI (10-250 micrograms/Kg, IV) produced both hypertension and tachycardia in rats. The results indicate that pineal stimulation activates brain 5-HT receptors and results in sympathetic stimulation or parasympathetic inhibition which leads to hypertension and tachycardia in rats.
Chuang
J I
JI
Department of Physiology, National Cheng Kung University Medical College, Tainan City, Taiwan, R.O.C.
Lin
M T
MT
D000818:Animals; D001369:Axons / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D003533:Cyproheptadine / Q000494:pharmacology; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000502:physiology; D010870:Pineal Gland / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology; D013610:Tachycardia / Q000139:chemically induced / Q000503:physiopathology*; D014628:Vagotomy
D003533:Cyproheptadine; D012701:Serotonin; D007608:Kainic Acid