Pineal hyperactivity in spontaneously hypertensive rats: muscarinic regulation of indole metabolism.
1. Choline acetyltransferase activity and [3H]quinuclidinyl benzylate-binding sites were detected in the pineal gland of normotensive Wistar-Kyoto rats and of spontaneously hypertensive rats. 2. In vitro, muscarinic activation by pilocarpine increased the pineal metabolic production of hydroxyindole derivatives up to 5-hydroxytryptamine and produced a less marked stimulation of melatonin biosynthesis. 3. Electrical field stimulation of pineal gland slices caused similar metabolic effects. 4. Muscarinic blockade with atropine inhibited the effects on hydroxyindole metabolism. 5. [3H]Quinuclidinyl benzylate-binding sites, indicative of muscarinic receptors, were more numerous, and basal 5-hydroxytryptamine and melatonin levels were higher, in the pineal gland of spontaneously hypertensive rats compared with Wistar-Kyoto rats. 6. The atropine-sensitive metabolic effects of pilocarpine and electrical field stimulation on the pineal gland were increased in spontaneously hypertensive rats compared with Wistar-Kyoto rats.
Finocchiaro
L M
LM
Laboratorio de Sustancias Vasoactivas, Universidad de Buenos Aires, Argentina.
Scheucher
A
A
Alvarez
A L
AL
Finkielman
S
S
Nahmod
V E
VE
Pirola
C J
CJ
D000818:Animals; D004558:Electric Stimulation; D006973:Hypertension / Q000503:physiopathology*; D007211:Indoles / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000096:biosynthesis; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D010862:Pilocarpine / Q000494:pharmacology; D010870:Pineal Gland / Q000503:physiopathology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011976:Receptors, Muscarinic / Q000378:metabolism; D012701:Serotonin / Q000096:biosynthesis
D007211:Indoles; D011976:Receptors, Muscarinic; D010862:Pilocarpine; D012701:Serotonin; D008550:Melatonin