Thursday, December 22, 2005

Specific CYP displacement of 3HDPAT

1 ug/ml of CYP ( 2.85 micromolar ) displaces 83% of 3HDPAT, a 5HT1a ligand. 0.36 ug/ml CYP ( 1.03 micromolar ) displaces 40% of 3HDPAT.

3-0H CYP is somewhat better as a displacing drug (ligand) with total displacement of 3HDPAT by 1 ug/ml 3-OH CYP and 52% displacement by 0.36 ug/ml. This would make the concentration necessary for 50% displacement of the ligand, by 3-OH cyproheptadine, ~ 1.03 micromolar, assuming a molecuar weight of 3-OH cyproheptadine of 303 this, the IC50, would be 1.2 micromolar. See data, which is preliminary, below.

The IC50 for cyproheptadine relative to 3H-8-OH-DPAT was, in -log IC 50, M, 6.01, cf. Josee E. Leysen in Neurophamacology of Serotonin, p. 86. In this book, p. 302, is also reported "Cyproheptadine and methysergide inhibit the firing of raphe neurons when applied locally (Haigler and Aghajanian 1974)." This is consistent with a locus coeruleus action posited in my 1991 case reports re: nightmares.


References:

A. Richard Green (ed), Neuropharmacology of Serotonin, Oxford University Press, 1985

In Green, for IC50, cited:
Gozlan,H, et al., Hamon, M (1983), Identification of presynaptic autoreceptors using a new ligand: 3H-PAT. Nature 305, 140; Leysen JE (1981) Serotonergic receptors in brain tissue: Properties and idientification of various [3H]ligand binding sites in vitro. J. Physiol. 77, 351

Haigler, HJ, and Aghajanian, GK (1974) J. Neural. Transm., 35, 257.

re HT1a agonist effects and reversal:
Trickelbank, MD (1984a) Behavioural effects of 8-hydroxy-2-(di-n-propylamine) tetralin, Br. J. Pharmac. 81, 26P, see also 140P.
Oberlander L cited in Green p 363 also has contributions.

Wednesday, December 21, 2005

Specific CYP Binding (cell cpm - NS binding)

Specific CYP Binding (cell cpm - 824)

TB
827
1453

1 ug/ml CYP
238
92
45
420

0.36 ug/ml. CYP
544
503
309

Tuesday, December 20, 2005

Cyproheptadine binding

CPM

TB (3HDPAT, no cold) 1651 Average = 1966
2277 population s.d. = 311


NS (nonspecific, i.e. with excess 'cold') Average = 824
867 population s.d. = 44
780

1 ug/ml CYP 1200 Average = 1062
916 population s.d. = 160
869
1244

0.36 ug/ml CYP 1368 Average = 1276
1327 population s.d. = 102
1133

150 ul 3HDPAT straight (no MRB) 24998



from workbook p.93

Sunday, December 18, 2005

Statistical Specific 3-0H CYP CPM Binding

CPM

TB (only 3HDPAT) Average = 2196
population s.d. 380


1ug 3-OHCYP Average = -168 (thus total displacement by 1 ug 3-OH CYP)
population s.d. 205

0.36 ug 3-OHCYP Average 1140
population s.d. 393

Thus 0.36 ug 3-OHCYP displaces 52% of a specific binder of 5HT1a 3HDPAT.

Friday, December 16, 2005

Specific Binding 3-OH CYP CPM

CPM

TB (only 3HDPAT) 2577
1816

1 ug 3-OHCYP -224
106
-388

0.36 ug 3-OHCYP 1564
1238
617


Created by subtracting CPM(20uM)5HT (which is nonspecific binding) from CPM for other groups. Starting data below.

3-OH Displacement

CPM

TB 4914
(no cold) 4153


20 uM 5HT 2337


1 ug 3-OHCYP 2113
2443
1949

0.36 ug 3-OHCYP 3901
3575
2954