Sympathetic denervation and chronic serotonin uptake blockade by fluoxetine do not affect pineal gland 5-hydroxyindole acetic acid: evidence that oxidative deamination of pineal serotonin is a property of the pinealocyte

1992 ◽  
Vol 89 (1-2) ◽  
pp. 93-101 ◽  
Author(s):  
J. A. McNulty ◽  
V. Colin
Keyword(s):  
Acetic Acid ◽  
Pineal Gland ◽  
Serotonin Uptake ◽  
Sympathetic Denervation ◽  
Oxidative Deamination ◽  
Pineal Serotonin

Day/night serotonin levels in the pineal gland of male BALB/c mice with melatonin deficiency

1988 ◽  
Vol 117 (1) ◽  
pp. 93-98 ◽  
Author(s):  
L. Vollrath ◽  
A. Huesgen ◽  
B. Manz ◽  
K. Pollow
Keyword(s):  
Detection Limit ◽  
Pineal Gland ◽  
Genetic Defect ◽  
Laboratory Mice ◽  
Serotonin Synthesis ◽  
Adrenergic Agonist ◽  
Adrenergic Mechanisms ◽  
Melatonin Synthesis ◽  
Number Of Species ◽  
Pineal Serotonin

Abstract. Studies from another laboratory have shown that several strains of laboratory mice have a genetic defect for melatonin synthesis. In non-deficient species, melatonin synthesis undergoes a typical, β-adrenergically regulated day/night rhythm with low melatonin levels during daytime and high levels at night, the precursor serotonin showing an inverse behaviour. This study examines whether a day/night rhythm of pineal serotonin levels exists in melatonin-deficient male BALB/c mice. Mice kept under a lighting schedule of 12 h light (lights on at 07.00 h) and 12 h dark were killed at 13.00 and 01.00 h, respectively. Serotonin amounted to 12-15 ng/pineal and did not show regular day/night differences. Administration of the β-adrenergic agonist, isoproterenol, which is known to affect melatonin synthesis in a number of species, was without effect on pineal serotonin levels. Melatonin and two of the melatonin-forming enzymes, serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) were below the detection limit in the pineal. It is concluded that in melatonin-deficient BALB/c mice, pineal serotonin synthesis is apparently intact. In BALB/c mice, serotonin synthesis and release do not appear to be directly or indirectly regulated by β-adrenergic mechanisms.

Degeneration activity of the pineal gland after sympathetic denervation

1982 ◽  
Vol 321 (4) ◽  
pp. 298-301 ◽  
Author(s):  
M. A. Luchelli-Fortis ◽  
F. J. E. Stefano ◽  
C. J. Perec
Keyword(s):  
Pineal Gland ◽  
Sympathetic Denervation ◽  
Degeneration Activity

scholarly journals Contamination of the Norepinephrine Prodrug Droxidopa by Dihydroxyphenylacetaldehyde

2010 ◽  
Vol 56 (5) ◽  
pp. 832-838 ◽  
Author(s):  
Courtney Holmes ◽  
Noel Whittaker ◽  
Jorge Heredia-Moya ◽  
David S Goldstein
Keyword(s):  
Acetic Acid ◽  
Liquid Chromatography ◽  
Acid Solution ◽  
Orthostatic Hypotension ◽  
Acidic Solution ◽  
Venous Blood ◽  
Oxidative Deamination ◽  
Catecholaminergic Neurons ◽  
The Mean ◽  
Sampling Times

Abstract Background: l-Threo-3,4-dihydroxyphenylserine (L-DOPS, droxidopa) is a norepinephrine (NE) prodrug under development to treat orthostatic hypotension. 3,4-Dihydroxyphenylacetaldehyde (DOPAL), an endogenous catecholaldehyde produced by enzymatic oxidative deamination of dopamine, is toxic to catecholaminergic neurons. Based on the observation of increasing plasma DOPAL after oral administration of L-DOPS to a patient, we examined whether other subjects also had DOPAL in their plasma after droxidopa administration, and whether droxidopa is contaminated with DOPAL. Methods: Thirteen subjects took 400 mg droxidopa orally. We sampled venous blood at baseline and 1, 2, 3, 6, 24, and 48 h after drug administration and assayed L-DOPS, NE, and DOPAL by use of liquid chromatography with electrochemical detection (LC-ED). Droxidopa in acidic solution (20:80 mixture of 0.04 mol/L phosphoric acid:0.20 mol/L acetic acid) was vacuum centrifuged for 1 h at 30 °C and then assayed by LC-ED. Results: Droxidopa contained 0.01% DOPAL. At 6 h after droxidopa, all subjects had detectable DOPAL in plasma (1.89 nmol/L, P = 0.0001). Across the sampling times, plasma DOPAL correlated with plasma L-DOPS (r = 0.996). The mean increment in plasma DOPAL was more than 4 times that in plasma NE (0.39 nmol/L). In 2 patients with Parkinson disease and orthostatic hypotension, DOPAL was detected in plasma at baseline (0.12 nmol/L) and increased by about 70-fold after droxidopa. Vacuum concentration of droxidopa in the acid solution converted L-DOPS to DOPAL completely. Conclusions: Droxidopa is contaminated with DOPAL. After oral droxidopa administration, DOPAL is detected in plasma of humans. Droxidopa is susceptible to extensive nonenzymatic conversion to DOPAL.

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