Melatonin in rat milk and the likelihood of its role in postnatal maternal entrainment of rhythms

2002 ◽  
Vol 282 (3) ◽  
pp. R797-R804 ◽  
Author(s):  
Shawn A. Rowe ◽  
David J. Kennaway
Keyword(s):  
Peak Plasma ◽  
Subcutaneous Administration ◽  
Melatonin Secretion ◽  
Plasma Melatonin ◽  
Rat Pups ◽  
Propranolol Administration ◽  
Maternal Entrainment

The rhythm of melatonin in rat milk and the capacity of pups to synthesize and metabolize melatonin were studied. Melatonin was undetectable in milk in the light (<21 pM), but increased rapidly 2–4 h after dark to peak at 357 ± 66 pM at mid-dark. Oral or subcutaneous administration of melatonin to 5- and 10-day-old pups resulted in peak plasma melatonin levels 30 min after administration and rapid metabolism. Increases in pineal and plasma melatonin levels at night were detected at 5 and 6 days of age, respectively. Isoproterenol administration (2 μg/g body wt) at mid-light to day 10 pups increased plasma melatonin from 312 ± 40 pM to 1,298 ± 160 pM, whereas propranolol (2 μg/g body wt) suppressed nocturnal melatonin secretion from 1,270 ± 128 pM to 395 ± 66 pM. The rise of pineal and plasma melatonin in day 10 pups occurred 1 and 2 h after dark onset, respectively, preceding the onset in dams by 3 and 4 h, respectively. Propranolol administration to 2- and 5-day lactating dams inhibited plasma and milk melatonin at night but had no effect on their suckling pups. Transfer of melatonin via the milk is unlikely to provide an entraining signal for rat pups.

The Effect of Moderate Weight Loss on Overnight Melatonin Secretion

1990 ◽  
Vol 156 (6) ◽  
pp. 875-877 ◽  
Author(s):  
I. M. Anderson ◽  
S. E. Gartside ◽  
P. J. Cowen
Keyword(s):  
Weight Loss ◽  
Melatonin Level ◽  
Melatonin Secretion ◽  
Plasma Melatonin ◽  
Healthy Women ◽  
Before And After

Overnight plasma melatonin level was measured in ten healthy women before and after a 4300 kJ (1000 kcaI) diet in which they lost an average 3.1 kg. This weight loss did not significantly alter melatonin levels.

Annual changes in 6-sulphatoxymelatonin excretion in man

1988 ◽  
Vol 117 (4) ◽  
pp. 470-476 ◽  
Author(s):  
Christopher J. Bojkowski ◽  
Josephine Arendt
Keyword(s):  
Intermediate Phase ◽  
Urine Samples ◽  
Plasma Samples ◽  
Annual Change ◽  
Melatonin Secretion ◽  
Normal Volunteers ◽  
Plasma Melatonin ◽  
Annual Rhythm ◽  
Major Urinary Metabolite ◽  
Annual Changes

Abstract: A recently developed RIA for 6-sulphatoxymelatonin, the major urinary metabolite of melatonin, has been used to investigate the annual change in melatonin secretion in humans. Twenty plasma samples were taken from 18 volunteers throughout a 24-h period and simultaneous 6-hourly urine samples were also collected. Plasma melatonin and urinary 6-sulphatoxymelatonin were measured by RIA. 6-Sulphatoxymelatonin assayed in the urine samples was shown to be a good index of the rhythmic characteristics of the plasma melatonin secretion. To study annual changes in excretion four sequential 6-hourly urine samples were collected at monthly intervals from 16 normal volunteers for 13 months. Cosinor curves were fitted to the 6-sulphatoxymelatonin excretion data and the 24-h rhythm was described by the cosinor parameters: amplitude, mesor and acrophase. Significant differences in the acrophase were found during the year. The summer acrophase was phase advanced relative to the winter acrophase by about 1.5 h while intermediate phase positions were observed in spring/autumn. The 24-h excretion of urinary 6-sulphatoxymelatonin was remarkably consistent and there was no annual rhythm. In contrast, the daytime 6-sulphatoxymelatonin excretion between 12.00–18.00 h showed a statistically significant seasonal rhythm, with peaks in December/January and in July.

scholarly journals Plasma and tissue clindamycin antimicrobial activity after parenteral administration to cats under surgical conditions

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Sabrina Passini ◽  
Laura Montoya ◽  
Martín Lupi ◽  
Paula Lorenzini ◽  
María Fabiana Landoni ◽  
...  
Keyword(s):  
Peak Plasma ◽  
Subcutaneous Tissue ◽  
Plasma Concentrations ◽  
Subcutaneous Administration ◽  
Dose Interval ◽  
Tissue Concentrations ◽  
Administration Routes ◽  
Infection Treatment ◽  
Plasma Concentration Ratio ◽  
Surgical Conditions

Clindamycin plasma and tissue disposition in cats under surgical conditions after a single intravenous (IV), intramuscular (IM) and subcutaneous (SC) administration at a dose rate of 10 mg/kg were studied. After intravenous, intramuscular and subcutaneous administration, peak plasma concentrations were 10.93±3.78 μg/mL (Cp(0)), 5.93±1.18 μg/mL (Cmax)) and 6.30±0.88 μg/mL (Cmax)), respectively. Eight hours after clindamycin IV, IM and SC administration plasma concentrations declined to 2.01±0.61 μg/mL, 2.96±0.43 μg/mL and 3.36±0.97 μg/mL, respectively. Sixty to 90 minutes after clindamycin administration, tissue concentrations ranged from a minimum in subcutaneous tissue of 4.90 μg/g (IV), 3.06 μg/g (IM) and, 3.13 μg/g (SC) to a maximum in uterus of 13.41 μg/g (IV), 14.07 μg/g (IM) and, 14.44 μg/g (SC). The lowest tissue/plasma concentration ratio for the three administration routes was observed in subcutaneous tissue, while the highest was observed at genital level (ovary for IV and IM and uterus for SC). Estimated efficacy predictor (AUC/MIC), considering MIC breakpoint for bacteria isolated from animals, indicates that clindamycin administered IV, IM or SC at the studied dose is appropriated for perioperative prophylactic protocols and that given with a dose interval of 12 hours would be effective for susceptible infection treatment in cats.

scholarly journals Pharmacokinetics of Tildipirosin in Ewes after Intravenous, Intramuscular and Subcutaneous Administration

Animals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1332
Author(s):  
Juan Sebastián Galecio ◽  
Elisa Escudero ◽  
José Joaquín Cerón ◽  
Giuseppe Crescenzo ◽  
Pedro Marín
Keyword(s):  
Bacterial Infections ◽  
High Performance ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Subcutaneous Administration ◽  
Apparent Volume ◽  
Wide Distribution ◽  
Volume Of Distribution ◽  
Time Data ◽  
Administration Time

A single-dose disposition kinetics for tildipirosin was evaluated in clinically healthy ewes (n = 6) after intravenous (IV), intramuscular (IM), and subcutaneous (SC) administration of a commercial formulation. Tildipirosin concentrations were determined by high-performance liquid chromatography with ultraviolet detection. Plasma concentration-time data was calculated by non-compartmental pharmacokinetic methods. The apparent volume of distribution (Vz) of tildipirosin after IV administration was 5.36 ± 0.57 L/kg suggesting a wide distribution in tissues and inside the cells. The elimination half-life (t½λz) was 17.16 ± 2.25, 23.90 ± 6.99 and 43.19 ± 5.17 h after IV, IM and SC administration, respectively. Following IM administration, tildipirosin was rapidly absorbed (tmax = 0.62 ± 0.10 h) even to a greater extent than after SC administration. Time to reach peak concentration (tmax) and peak plasma concentrations (Cmax) differed significantly, but both parameters showed a more significant variability after SC than after IM administration. Bioavailabilities after extravascular administration were high (>70%). Therefore, given general adverse reactions that were not observed in any ewe and favourable pharmacokinetics, tildipirosin could be effective in treating bacterial infections in sheep.

Inhibition of nighttime melatonin secretion in cattle: threshold light intensity for dairy heifers

2001 ◽  
Vol 81 (1) ◽  
pp. 153-156 ◽  
Author(s):  
T. J. Lawson ◽  
A. D. Kennedy
Keyword(s):  
Light Intensity ◽  
Key Words ◽  
Latin Square ◽  
Exposure Period ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Dairy Heifers ◽  
Plasma Melatonin ◽  
Light Intensities ◽  
Lower Light

Five pre-pubertal Holstein heifers were exposed for 16 h to a light intensity of 400 lx and thereafter to intensities of 0, 50, 100, 200, or 400 lx for an additional 8 h (5 x 5 Latin square design). Exposure to all intensities inhibited (P < 0.05) melatonin secretion for the initial few hours (of the 8-h exposure period); melatonin concentration subsequently increased, particularly with the lower light intensities. Only the highest light intensity (400 lx) suppressed (P < 0.05) plasma melatonin concentrations for the entire 8-h exposure period. Key words: Threshold, supplemental, light, intensity, inhibition, melatonin, heifer

scholarly journals Genetic variability in melatonin secretion originates in the number of pinealocytes in sheep

2002 ◽  
Vol 172 (2) ◽  
pp. 397-404 ◽  
Author(s):  
A Gomez Brunet ◽  
A Gomez Brunet ◽  
B Malpaux ◽  
A Daveau ◽  
C Taragnat ◽  
...  
Keyword(s):  
Genetic Variability ◽  
Pineal Gland ◽  
Melatonin Secretion ◽  
High Group ◽  
Plasma Melatonin ◽  
Genetic Groups ◽  
Mean Size ◽  
The Mean ◽  
Genetic Value ◽  
The Brain

Genetic variability in plasma melatonin concentrations in ewes results from variations in pineal weight. This study investigated whether it is due to a difference in the number of pinealocytes, or in their size. Two groups of lambs were assigned before birth to being extremes (18 High and 21 Low) by calculating their genetic value on the basis of the melatonin concentrations of their parents. Lambs were bled from 1 week of age until 14 weeks of age. Pineal gland, brain and pituitary weights, length and width of the brain, and length of the hypothalamus were recorded. A significant effect (ANOVA) of genetic group (P<0.05) and age (P<0.05) was detected on mean nocturnal plasma melatonin concentrations, as soon as the first week after birth (mean +/- s.e.m.; High: 51.7 +/- 10.7 vs Low: 31.9 +/- 3.2 pg/ml). There was no difference between the two genetic groups in any of the brain parameters measured, but the pineal glands of the High group were heavier and contained significantly more pinealocytes (High: 27.8 +/- 2.4 vs Low: 21.0 +/- 2.4 x 10(6); P<0.05) than those in the Low group. The mean size of pinealocytes did not differ between the two genetic groups. Thus, the genetic variability in nocturnal plasma melatonin concentrations in sheep is expressed by 1 week of age and higher levels of secretion are the consequence of larger pineal glands containing a greater number of pinealocytes.

scholarly journals Pharmacokinetics and Pharmacodynamics of Fosfomycin and Its Activity against Extended-Spectrum-β-Lactamase-, Plasmid-Mediated AmpC-, and Carbapenemase-ProducingEscherichia coliin a Murine Urinary Tract Infection Model

2018 ◽  
Vol 62 (6) ◽  
Author(s):  
Ilya Nikolaevich Zykov ◽  
Ørjan Samuelsen ◽  
Lotte Jakobsen ◽  
Lars Småbrekke ◽  
Dan I. Andersson ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Subcutaneous Administration ◽  
Clinical Strain ◽  
Infection Model ◽  
Time Curve ◽  
Content Type ◽  
Tract Infections

ABSTRACTFosfomycin has become an attractive treatment alternative for urinary tract infections (UTIs) due to increasing multidrug resistance (MDR) inEscherichia coli. In this study, we evaluated the pharmacokinetic (PK) and pharmacodynamic (PD) indices of fosfomycin and itsin vivoactivity in an experimental murine model of ascending UTI. Subcutaneous administration of fosfomycin showed that the mean peak plasma concentrations of fosfomycin were 36, 280, and 750 mg/liter following administration of a single dose of 0.75, 7.5, and 30 mg/mouse, respectively, with an elimination half-life of 28 min, and urine peak concentrations of 1,100, 33,400, and 70,000 mg/liter expected to be sustained above 1 mg/liter (MIC of the test strain, NU14) for 5, 8, and 9.5 h, respectively. The optimal PK/PD indices for reducing urine colony counts (number of CFU per milliliter) were determined to be the area under the concentration-time curve/MIC from 0 to 72 h and the maximum concentration/MIC on the basis of the dose-dependent bloodstream PK and the results of an evaluation of six dosing regimens. With a dosing regimen of 15 mg/mouse twice (every 36 h), fosfomycin significantly reduced the number of CFU per milliliter of all susceptible strains in urine, including clinical MDR strains, except for one clinical strain (P= 0.062). Variable degrees of reduction were observed in the bladder and kidneys. No significant reductions in the number of CFU per milliliter were observed with the resistant strains. In conclusion, fosfomycin shows concentration-dependentin vivoactivity, and the results suggest that fosfomycin is an effective alternative to carbapenems in treating MDRE. coliin uncomplicated UTIs. The data on the effectiveness of fosfomycin against the MDR isolates along with the results of PK/PD modeling should facilitate the further development of improved recommendations for its clinical use.

scholarly journals Testis development in the Japanese eel is affected by photic signals through melatonin secretion

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12289
Author(s):  
Ji-Yeon Hyeon ◽  
Jun-Hwan Byun ◽  
Eun-Su Kim ◽  
Yoon-Seong Heo ◽  
Kodai Fukunaga ◽  
...  
Keyword(s):  
Close Association ◽  
Japanese Eel ◽  
Constant Darkness ◽  
Melatonin Secretion ◽  
Time Resolved ◽  
Migration Patterns ◽  
Testis Development ◽  
Plasma Melatonin ◽  
Short Day ◽  
And Migration

Objective According to reported spawning characteristics of Japanese eel, Anguilla japonica, which exhibit spawning and migration patterns that are synchronized with lunar cycles and photoperiod, we hypothesized that a close association exists between specific photic signals (daylight, daylength, and moonlight) and endocrinological regulation. Given the photic control in melatonin secretion, this hypothesis was tested by investigating whether melatonin signals act as mediators relaying photic signals during testis development in the eel. Methods We examined changes in melatonin-secretion patterns using time-resolved fluorescence immunoassays in sexually immature and mature male Japanese eels under the condition of a new moon (NM) and a full moon (FM). Results The eye and plasma melatonin levels exhibited a nocturnal pattern under a 12-h light: dark cycle (12L12D) or under constant darkness (DD), but not with constant light (LL). Eye melatonin levels were similar under the 12L12D and short-day (9L15D) conditions. In the long-day condition (15L9D), secreted plasma melatonin levels were stable, whereas short-day melatonin secretion began when darkness commenced. Sexual maturation began at 8 weeks following intraperitoneal injection of human chorionic gonadotropin (hCG), and NM exposure led to significantly higher eye and plasma melatonin levels compared with those detected under FM exposure.

Enhanced circadian rhythm of melatonin in anorexia nervosa

1989 ◽  
Vol 120 (5) ◽  
pp. 574-578 ◽  
Author(s):  
Federico Tortosa ◽  
Manuel Puig-Domingo ◽  
Miguel-Angel Peinado ◽  
Josep Oriola ◽  
Susan M. Webb ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Weight ◽  
Anorexia Nervosa ◽  
Circadian Rhythm ◽  
Pineal Gland ◽  
Control Group ◽  
Melatonin Secretion ◽  
Plasma Melatonin ◽  
Pineal Function ◽  
The Mean

Abstract. Plasma melatonin circadian profiles were investigated in a group of 4 patients with anorexia nervosa and 4 healthy regularly cycling women. There were no differences in the mean age of both groups, whereas the anorexia nervosa patients had lower mean body weight (37.8 ± 2.0 vs 57.0 ± 4.9 kg) and body mass index (13.9 ± 1.1 vs 20.8 ± 2.0). Samples were collected every 2 h and plasma melatonin was measured by using a RIA with an iodinated tracer. Anorexia nervosa patients exhibited higher diurnal (60.7 ± 1.8 vs 25.4 ± 1.72 pmol/l, P< 0.02) and nocturnal (419.2 ± 37.4 vs 108.0 ± 33.6 pmol/l), P< 0.001) mean plasma melatonin concentrations. There were no differences in the time peak for nocturnal melatonin secretion in both groups, detected at 02.00 h. In anorexia nervosa, the melatonin circadian profile paralleled that observed in the control group, indicating that the increased melatonin values for anorexia nervosa were probably due to an enhanced secretory pineal function rather than an impaired melatonin metabolism. These results suggest a participation of the pineal gland in the pathophysiology of anorexia nervosa.

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