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  • 1
    Electronic Resource
    Electronic Resource
    Hormonal Modulation of Pineal-Mediated Seasonal Events: Effects of Thyroid or Gonadal Manipulations (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: The ability of various manipulations of the endocrine system to affect pineal mediated events was examined in the present studies. Male Syrian hamsters were analyzed for pineal-induced gonadal regression and depressions in serum thyroxine and testosterone levels after treatments which altered thyroid or gonadal function. Hamsters were thyroidectomized, received thyroxine implants (5 mg), or were thyroidectomized plus implanted with thyroxine. The animals were exposed to short photoperiods (10L:14D) for 9 wk, and plasma hormone levels and gonadal status were determined at the end of the experimental period. Likewise, hamsters were castrated, received testosterone implants (5 mg), or were castrated plus implanted with testosterone, and subsequently were exposed to short photoperiods for 9 wk. These animals' responses to photoperiod exposure were compared to animals which received identical hormonal treatments but remained in long photoperiod (14L:10D). All of the hamsters responded to the photoperiodic treatments equally, regardless of the hormonal treatment. The results of these studies indicate that experimentally induced alterations in plasma thyroxine or testosterone levels are unable to prevent or attenuate the ability of the pineal to elicit gonadal regression in response to short photoperiod exposure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1988.tb00648.x
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  • 2
    Electronic Resource
    Electronic Resource
    Pineal serotonin is resistant to depletion by serotonergic neurotoxins in rats (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 11 (1991), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Administration of 3,4-methylenedioxymethamphetamine (MDMA) or para-chloroamphetamine (pCA) to adult rats is neurotoxic to serotonin (5HT) nerve terminals and cell bodies. MDMA (10 mg/kg) reduces; 5HT levels in the frontal cortex, medial basal hypothalamus, and striatum acutely and 17 days after a series of multiple injections. The acute reductions occur within 1–2 hr after injection of doses greater than 3 mg/kg. A single injection of pCA reduces 5HT levels in the above mentioned brain regions as well as in the brain stem. However, none of these treatments are able to alter 5HT levels in the pineal gland. It appears that the pineal does not contain the 5HT reuptake system that is thought to be necessary for the neurotoxicity of MDMA and pCA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1991.tb00473.x
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  • 3
    Electronic Resource
    Electronic Resource
    Propranolol Blockade of Short Photoperiod-Induced Gonadal Regression: Modification by Melatonin Injections or Implants (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 9 (1990), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Male Syrian hamsters were exposed to short photoperiods (10L: 14D) for ten weeks and received daily ethanolic saline (1:10), propranolol (125 μg, sc) or melatonin (25 μg, sc) injections at 16: 45. Some hamsters also received melatonin implants (1 mg in 24 mg beeswax, sc) every two weeks in addition to the above treatments. Testicular weights were determined at the beginning, every three weeks, and at the end of the experiment. Serum hormone levels, hypothalamic amine levels and cortical amine levels were also determined at the conclusion of the experiment. Propranolol prevented the decline in testes weight produced by short photoperiod (P〈0.001 versus control). Propranolol was not able to prevent daily injections of melatonin from producing gonadal regression. Melatonin implants blocked testicular regression produced by both short photoperiod and melatonin injections. No differences in hypothalamic or cortical amine levels were observed between the treatment groups. These results add further support to the suggestion that propranolol is acting at the pineal gland preventing melatonin synthesis and not at a post-pineal central site which would affect melatonin binding and action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1990.tb00695.x
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  • 4
    Electronic Resource
    Electronic Resource
    Pharmacological Studies on the Regulation of N-Acetyltransferase Activity and Melatonin Content of the Pineal Gland of the Syrian Hamster (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: Thus far, all attempts to stimulate melatonin synthesis by β-adrenergic receptor agonists in the Syrian hamster pineal gland have failed. Neither a wide range of dosages of isoproterenol (0.5 mg/kg to 24 mg/kg), nor prolonged treatment with norepinephrine, the natural neurotransmitter, increased N-acetyltransferase (NAT) activity or melatonin production. In the present study, the administration of isoproterenol at night was likewise ineffective in advancing or enhancing the normal nightly melatonin peak. Also, we did not find a delayed effect 7 or 8 h after the administration of the drug. Furthermore, we tested the idea of coneurotransmitters such as octopamine or dopamine being possibly necessary for stimulation, but could not find any effect of these substances on melatonin synthesis. In addition, a parasympatholytic agent, atropine, did not increase the responsiveness to sympathomimetic agents. Administration of a phosphodiesterase inhibitor was also ineffective in stimulating NAT activity. On the other hand, isoproterenol did retard the drop in NAT and melatonin after lights-on at night, indicating that β-receptors are involved in maintaining elevated melatonin levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1985.tb00632.x
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  • 5
    Electronic Resource
    Electronic Resource
    Time-dependent effects of melatonin on immune measurements in male Syrian hamsters (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 25 (1998), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Adult, male Syrian hamsters received daily subcutaneous melatonin (25 μg) injections or vehicle injections at 08:00 or 17:00 hr for 11 weeks. Body weights were measured weekly throughout the experiment and testes weights, spleen weights, and serum was collected at the end of the experiment. The spleens were sectioned and immunocytochemically analyzed for immunoglobulin G and serum levels of interferon-gamma, interleukin-2, and interleukin-4 were determined in heterologous mouse assays. Melatonin injections at 17:00 hr, but not at 08.00 hr, increased body weights, decreased testes weights and serum testosterone levels, and had no effect on immunoglobulin G content in the spleen. Likewise, melatonin injections at 17:00 hr, but not at 08:00 hr, increased serum interferon-gamma levels, had no effect on interleukin-2 levels, and appeared to increase interleukin-4 levels. Since melatonin injections at 08:00 hr were ineffective in altering immune measurements and correlations between reproductive measures and immune measures were high, the most parsimonious explanation for these results is that melatonin injections at 17:00 hr depressed reproductive hormone levels and these depressed levels altered immune measures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1998.tb00552.x
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  • 6
    Electronic Resource
    Electronic Resource
    Relative Efficacy of Melatonin and 5-Methoxytryptamine in Terms of Their Antigonadotrophic and Counterantigonadotrophic Actions in Male Syrian Hamsters (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 1 (1984), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Antigonadotrophic and counterantigonadotrophic activities of melatonin and 5-methoxytryptamine (5-MT) were quantitatively compared in male Syrian hamsters. In long day conditions, the daily afternoon administration of either 5, 15, 25, 50, 100 or 200 μg melatonin induced testicular regression within 10 wk; under the same circumstances, only the 200-μg dosage of 5-MT was able to suppress testicular weights. Thus, 5-MT appears to have about one-tenth the antigonadotrophic action of melatonin in the male Syrian hamster. In short days, the subcutaneous implantation of either 50 or 100 μg melatonin (every 2 wk in beeswax) prevented testicular regression whereas it required much larger doses of 5-MT (1 mg every 2 wk in beeswax) to achieve the same counterantigonadotrophic action. In terms of both their antigonadotrophic and counterantigonadotrophic effects, hamsters seem to be more sensitive to melatonin than to 5-MT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1984.tb00199.x
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  • 7
    Electronic Resource
    Electronic Resource
    Acute and chronic effects of melatonin as an anticonvulsant in male gerbils (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 20 (1996), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Melatonin, a hormone produced in the pineal gland and released into the general circulation on a diurnal basis, has been implicated in many behavioral processes, where it has been shown to have anxiolytic, sedative, and anticonvulsant effects. Male gerbils (Meriones unguiculatus) injected daily with melatonin (25 μg, s.c.) exhibited a reduced seizure response to pentylenetetrazol (PTZ, 60 mg/kg, s.c). The present studies determined 1) whether melatonin's effect was related to the time of day that it was administered and 2) whether a single acute injection of melatonin at various doses could produce anticonvulsant activity. Gerbils provided with 13 weeks of daily melatonin injections (25 μg, s.c.) exhibited fewer convulsions after PTZ treatment irrespective of the time of day melatonin was injected. In addition, the melatonin-treated gerbils had lower mortality rates (1/12) than the untreated or vehicle-injected gerbils (5/12). On the other hand, single acute injections of melatonin (0.1–10 mg/kg, i.p.) produced no anticonvulsant activity. It appears that the anticonvulsant effects of melatonin occur only after the animals are chronically exposed to the indole. In addition, melatonin's anticonvulsant ability may utilize a different mechanism than those involved in its endocrine effects, since no diurnal difference in melatonin's anticonvulsant activity was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1996.tb00243.x
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of the Effects of β-Adrenergic Agents on Pineal Serotonin N-Acetyltransferase Activity and Melatonin Content in Two Species of Hamsters (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 1 (1984), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The nighttime rise in pineal melatonin levels can be blocked by administration of the β-adrenergic receptor antagonist, propranolol, in both Syrian hamsters and rats. Although the administration of β-adrenergic receptor agonists such as norepinephrine or isoproterenol stimulates pineal melatonin production in the rat, these drugs are without apparent effect on indole production in the Syrian hamster. To determine whether this lack of stimulatory effect in the Syrian hamster is characteristic of this species, a comparison of the effects of norepinephrine and isoproterenol on pineal serotonin N-acetyltransferase activity and melatonin content was conducted. In contrast to their lack of effect in the Syrian hamster, norepinephrine and isoproterenol stimulated pineal serotonin N-acetyltransferase activity and melatonin content in the Djungarian hamster. Hourly injection of norepinephrine during a continuation of light into the normal dark period stimulated increases in the activity of serotonin N-acetyltransferase and melatonin content in the Djungarian hamster but was without effect on these pineal parameters in the Syrian hamster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1984.tb00192.x
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  • 9
    Electronic Resource
    Electronic Resource
    Rotation of dissecting groups among different cadavers provides students of anatomy with increased opportunity to observe human variations (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 8 (1995), S. 412-413 
    Details
    ISSN: 0897-3806
    Keywords: human gross anatomy ; cadaver ; anatomical variability ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: One way to increase medical students' awareness of anatomical variability is the dissection of different cadavers throughout laboratory coursework. This report covers such a procedure successfully instituted in a human gross anatomy course. © 1995 WiIey-Liss, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ca.980080608
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  • 10
    Electronic Resource
    Electronic Resource
    Superior cervical ganglionectomy results in the loss of pineal concretions in the adult male gerbil (meriones unguiculatus) (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 211 (1985), S. 465-468 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Twelve weeks after bilateral superior cervical ganglionectomy, the number of pineal concretions in adult male gerbils was drastically decreased irrespective of photoperiodic treatment. These findings present further evidence that pineal concretions may be related to the metabolic activity of the gland. It is suggested that the pineal concretions of the gerbil are associated, in a yet unknown way, to the metabolism of the gland and that an active pineal is essential to maintain the large number of concretions seen in the normal state.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092110414
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