Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    New sensitive serum melatonin radioimmunoassay employing the Kennaway G280 antibody: Syrian hamster morning adrenergic response (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 15 (1993), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A new procedure with the G280 antibody of Kennaway provides an assay for circulating melatonin (aMT) with a sample volume (200 μl), an analytic (0.33 pg/ml) and functional (0.62–0.80 pg/ml) detectability, a 50% displacement dose (6.4 pg/ml), a Kd (0.657 pM), and measured circulating daytime levels lower than reported for previous procedures, and 100% assay recovery. The normal daytime range in adult human and Syrian hamster serum was 0.4–4 pg/ml. The pattern of fall of the nocturnal surge of Syrian hamster serum aMT near the time of lights-on was unaltered by extended darkness. Isoproterenol (ISO) injection 1 hr after lights-on, when aMT had reached daytime levels, raised serum and pineal aMT dramatically 2 hr postinjection. The same dose of ISO injected 4 hr into light produced only a small detectable increase. Novel extension of nocturnal darkness did not affect the responses to ISO. Thus, when they are allowed to occur at the usual time on a 10-hr dark schedule, both the fall from the nocturnal aMT surge and the subsequent loss of pineal beta-adrenergic responsiveness in this species occur endogenously (probably entrained) rather than from gating by acute effects of morning light. Changes in daytime serum aMT consistent with concomitant changes in the pineal can be measured with a sufficiently sensitive radioimmunoassay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1993.tb00514.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Elevated Environmental Temperature Alters the Responses of the Reproductive and Thyroid Axes of Female Syrian Hamsters to Afternoon Melatonin Injections (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 5 (1988), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Female Syrian hamsters were kept in a light (14: 10 h light: dark cycle, lights on 0600 h)- and temperature (22 or 30°C)-controlled room; some groups were treated with an afternoon s. c. injection of melatonin (6.25, 12.5, or 25 μg/day) for 11 or 14 weeks. The melatonin-induced suppression of the reproductive system in hamsters maintained at 22°C (as measured by vaginal cycles, uterine weights, ovarian histology, and plasma and pituitary prolactin levels) was delayed if hamsters were kept at 30°C. The dose-related depression of thyroxine (T4) after melatonin injections for 14 weeks in 22°C was not seen at 30°C. Rather, the depression of plasma T4 and triiodothyronine (T3) seen at the end of 11 or 14 weeks of exposure to 30°C without melatonin injections (vs. control levels at 22°C) was offset by melatonin injections, raising T4 and T3 particularly at the lower doses. In contrast, there was no consistent effect of higher temperature alone on reproductive variables. The interactive effects of temperature and melatonin on the reproductive and thyroidal systems in female hamsters are apparently complex and probably provide a fine-tuning mechanism for the environmental control of endocrine physiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1988.tb00656.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Rhythmic Melatonin Response of the Syrian Hamster Pineal Gland to Norepinephrine In Vitro and In Vivo (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 3 (1986), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Norepinephrine (NE, 10−6 M) stimulated melatonin accumulation in the incubation medium of rat (but not Syrian hamster) pineals taken at the end of the light phase. However, NE elevated melatonin accumulation in the medium of pineals taken after 20 min of light exposure of animals of either species at 6 h into the 10-h dark phase. A dose response to 10−7−10−5 M NE was observed in both the medium and pineals upon incubation of pineals taken from rats at 4 h into the light phase and from hamsters after 20 min light exposure at 6 h into the dark phase. Approximately 95% of the melatonin present was in the medium. The incubation time was 4 h in all cases. Subcutaneous injection of 1 μg/g NE (either at the end of the light phase or after 30 min of light at 6 h into the dark phase) did not stimulate in vivo Syrian hamster pineal melatonin content determined 1 or 2 h after injection, whether the hamsters were placed in light or darkness after the injection. However, after 30 min of light beginning at 6 h into dark, injection of 5 μg/g desipramine (DMI, a blocker of catecholamine uptake into nerve endings) allowed a dramatic hamster pineal melatonin response to additional injection of 1 μg/g NE, observed at 1 and 2 h in light after injection. A small effect of DMI alone was seen. DMI also potentiated the effect of NE (each 10−6 M) on melatonin accumulation in the medium of incubated hamster pineals taken after a short light exposure at night. No significant stimulatory effect of NE and/ or DMI was seen in vivo or in vitro near the middle of the light phase. Measurement of melatonin in the incubation medium is a useful method for studying pineal function. The Syrian hamster pineal has rhythm of sensitivity to NE (sensitivity evident at night) and even at night is protected by neuronal uptake from circulating NE-induced stimulation of melatonin production. NE appears to be the neurotransmitter for stimulation of pineal melatonin production in the Syrian hamster. The sensitivity rhythm and uptake protection might provide specificity of control of the nightly melatonin signal by reducing the chance of a melatonin response during the day or a response to circulating catecholamines from general sympathetic stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1986.tb00746.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Pineal Dependence of the Syrian Hamster's Nocturnal Serum Melatonin Surge (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 3 (1986), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The usual nocturnal surge of pineal melatonin content was blocked by bilateral superior cervical ganglionectomy in male Syrian hamsters. Ganglionectomy and pinealectomy each prevented the nocturnal rise of serum melatonin concentration seen in control animals. The normal nocturnal surge of circulating inelatonin in this species appears to depend on the pineal gland and its sympathetic innervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1986.tb00721.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Pineal Function in Burns: Melatonin Is Not a Marker for General Sympathetic Activity (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 2 (1985), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Burn injury in humans or rats is a model of marked elevation of general sympathetic activity for weeks, manifested in part by increased heart rate, metabolic rate, core temperature, and plasma and urinary catecholamines. Plasma melatonin was sampled at 2-h intervals for 24 h in 9 control subjects and 11 patients with severe burn injury. Daytime melatonin was not different between the groups, but nighttime values were significantly lower in the burn patients. A nocturnal surge was still significant in the patients. Resting heart rate and rectal temperature were elevated in the burn patients. In male Spraguc-Dawley rats, pineal melatonin content did not differ between controls and those with an experimental burn at 4 h into the light phase nor during the nocturnal surge. Male Syrian hamsters with burns had lower daytime pineal melatonin content than did controls, but the nocturnal surge in pineal melatonin was not significantly different between groups, nor was daytime morning serum melatonin. Sympathetic activity appears partitioned, with that controlling melatonin (nocturnal surge) regulated independently. In agreement with our previous findings in other models, melatonin is not a marker for general sympathetic activity, even following severe burn injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1985.tb00623.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Pineal-Induced Depression of Free Thyroxine in Syrian Hamsters (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 2 (1985), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Blind hamsters had no alteration of the dialyzable fraction of serum thyroxine (T4) but had depressed total and free T4 concentrations compared to controls. Prevention of the effects of blinding by pinealectomy indicates pineal influence on circulating free T4 concentration. Parallel changes in free T4 and the free T4 index indicate adequacy of the index in representing pineal-induced changes in free T4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1985.tb00713.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Sexual differences in 5′-deiodinase activity in the harderian gland of Syrian hamsters and the effect of pinealectomy: Regulation by androgens (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 62 (1996), S. 397-404 
    Details
    ISSN: 0730-2312
    Keywords: 5′-deiodinase activity ; Syrian hamster ; Harderian gland ; testosterone ; 5α-dihydrotestosterone ; pinealectomy ; rhythm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Sexual differences on thyroxine 5′-deiodinase (5′-D) in the Harderian gland of Syrian hamsters were investigated. We compared the 24-h profile of 5′-D activity in male and female hamsters, observing a clear rhythm in males but not in females. Female values were always significantly higher than male ones. After pinealectomy day/night variations in male 5′-D activity at the time points studies were abolished, results that are in correlation with serum thyroid hormones. We also studied the regulation by androgen of the enzyme activity. Basal 5′-D activity increased in castrated males and levels fell when animals were implanted with testosterone or its product 5α-dihydrotestosterone (DHT). Female 5′-D activity was also inhibited by androgens. As only the addition of DHT in the presence of epitestosterone, an inhibitor of the conversion of testosterone on DHT, in castrated males was able to decrease 5′-D activity to control animal levels, we suggest a probable direct effect of DHT by itself. © 1996 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...