Hormone effects on muscarinic cholinergic binding in bovine and rat sympathetic superior cervical ganglia

Gejman, P.V.; Cardinali, D.P.

Life Sciences 32(9): 965-972

1983


ISSN/ISBN: 0024-3205
PMID: 6402631
DOI: 10.1016/0024-3205(83)90926-8
Accession: 005587037

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Abstract
Muscarinic receptors were assessed by (3H)-quinuclidinyl benzilate (QNB) binding in 900 .times. g supernatants of bovine superior cervical ganglia (SCG). At 30.degree. C half maximal binding was reached within 3 min and equilibrium within 30 min. Scatchard analysis revealed a single population of binding sites with Kd = 0.15 .+-. 0.01 nM and site concentration (Bmax) = 101 .+-. 4 fmol/mg protein. Binding was specific for muscarinic drugs. Incubation of bovine SCG with different hormones (10-7 M) indicated that lutropin, TRH and testosterone depressed significantly Bmax, and that prolactin decreased both Kd and Bmax of (3H)-QNB binding. Several other hormones tested (TSH, growth hormone, FSH, LHRH, angiotensin II, bradykinin, melatonin, estradiol, thyroxine and triiodothyronine) did not affect QNB binding. Hormone effects were not due to a direct interference with radioligand binding to membrane. The injection of LH to orchidectomized rats depressed Bmax of SCG QNB binding without changing the Kd. Muscarinic cholinergic neurotransmission in SCG may be affected by hormones.