MUSCARINIC AGONISTS HAVE NO MEASURABLE EFFECT ON CGMP FORMATION OF RAT PINEALOCYTES

Previous studies have shown that muscarinic agonists stimulate cGMP fo rmation in various tissues including rat brain. As in the pineal gland cGMP formation varies considerably under various experimental conditi ons, in the present investigation the effects of muscarinic agonists w ere tested. Muscarinic agonists neither stimulated pineal cGMP formati on nor affected cGMP accumulation, resulting from administration of ph osphodiesterase (PDE) inhibitors, norepinephrine (NE), or sodium nitro prusside (SNP). Because muscarinic agonists are known to stimulate pin eal inositol phosphate (1p) formation we suspect that muscarine-relate d lp formation does not affect cGMP formation in rat pineal gland.