摘要:

Abstract:A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self‐recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T‐helper cell‐derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin‐induced‐immuno‐opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as ‐γ‐interferon and interleukin‐2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, dif

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00478.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract:The use of antisera raised against bovine growth hormone (GH) and ovine prolactin (PRL) enabled the detection of related immunoreactive (ir) sequences of proteins in ovine pineal tissue. The isolation of PRL‐like ir‐material was accomplished using a 0.25 M ammonium sulphate (pH 5.5) extraction followed by ethanol precipitation, whereas the resulting 2.0 M ammonium sulphate (pH 7.0) precipitate contained a GH‐like immunoreactivity. Gel chromatography of the GH‐like immunoreactivity (Sephadex G‐100) indicated the presence of several GH‐like fragments ranging in the Mrrange of 7,000 to 55,000. Analyses of the PRL‐like ir‐material found in pineal tissue on HPLC using a TSK 545‐DEAE column led to the resolution into a single peak of immunoreactivity. A single peak of activity was also observed following chromatofocusing and hydrophobic interaction chromatography of the ir‐peak from the TSK 545‐DEAE column. The PRL‐like ir‐material inhibited the binding of [125I]ovine PRL‐S14 to anti‐ovine PRL antibodies without showing an affinity for binding to anti‐rat PRL or anti‐bovine GH antibodies. Scatchard analysis of the binding of pineal PRL‐like ir‐material and pituitary ovine PRL‐S14 to liver membranes from day‐20 pregnant rats revealed similar affinity constants (Kaof 4.7 ± 0.2 × 109M‐1). In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL‐like ir‐material, an effect known to be specific for lactogenic hormones. The pineal PRL‐like immunoreactivity appeared on sodium dodecyl sulfate polyacrylamide gels as a single major band of Mr24,000. The functional status of PRL‐and GH‐like ir‐material in the ovine pineal remains to be determined, but evidence is presented that the overall protein synthesis rate of the

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00479.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract:Immunoreactive somatostatin (IRS) content in the pineal gland increased about two‐fold when the hypothalamic periventricular nucleus (Pe) of male rats, which contains many tuberoinfundibular somatostatin (SRIF) neuron cell bodies, was lesioned. However, the mechanism by which this increase takes place remains to be elucidated. Using125I‐Tyr11‐SRIF‐14 as a ligand and autoradiography, specific binding was detected in several brain areas. However, we were unable to detect specific SRIF binding sites either in the pineals of control or lesioned animals. This undetectable binding of SRIF‐14 could be due to the localization of low‐affinity receptors that were not demonstrated by the present method. Another possibility for the undetectable binding of the radioligand to the pineal could be due to the fact that the majority of IRS may be within the nerve terminals and the receptors in a differe

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00480.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract:The in vitro antiproliferative action of pineal indoles on several tumor cell lines including melanoma (B16), sarcoma (S180), macrophage‐like cell line (PU5), fibroblasts (3T3), and choriocarcinoma (JAr) was examined by measuring the incorporation of3H‐thymidine by the tumor cells, and, in the case of melanoma cells, by also measuring the incorporation of3H‐leucine and3H‐uridine. Uptake of crystal violet was used to assess the viability of the tumor cells. The order of inhibitory potency of the indoles was found to be methoxytryptamine>melatonin, methoxytryptophol, hydroxytryptophol, and methoxyindoleacetic acid>serotonin and hydroxyindoleactic acid. The possibility of an adverse effect of the indoles on the viability of normal cells was also investigated by employing a primary culture of rat hepatocytes. The release of glutamate‐oxaloacetate transaminase by hepatocytes was not affected by the indoles, although the release of glutamate‐pyruvate transaminase was increased to a small extent and the uptake of crystal violet was slight

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00481.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract:The presence of specific melatonin binding sites in the Harderian gland of Syrian hamsters was studied using [125I]melatonin. Saturation binding experiments conducted with [125I] melatonin at 37°C using Harderian glands of both male and female Syrian hamsters revealed a single nanomolar‐affinity site. The dissociation constants (Kd) were 6.47 and 6.94 nM for males and females, respectively. The concentration of the binding sites was 7.58 fmol/mg protein for males and 13.50 fmol/mg protein for females. Castration of male hamsters resulted in a significant increase in [125I] melatonin binding sites while chronic melatonin administration did not modify the binding properties. The results confirm the presence of melatonin binding sites in the Harderian glands of rodents. The gender‐associated differences found together with the effects of castration in male hamsters suggest an androgenic control in [125I] melatonin binding sites of the Syrian hamster Harderian g

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00482.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract:Glutamate, an excitatory neurotransmitter/neuromodulator involved in cell‐to‐cell communication within the central nervous system, is now believed to play a role in neuroendocrine function. In this study we describe a single, saturable, stereospecific, and temperature‐, time‐, and pH‐dependent binding site for glutamate in the pineal gland of the rat (Kd= 612 ± 23 nM, Bmax= 3.17 ± 0.33 pmol/mg protein). After removal of the sympathetic innervation to the pineal gland, [3H]glutamate binding displayed a higher apparent affinity (Kd= 412 ± 28 nM) (P<0.05) without a change in binding site number (Bmax= 3.60 ± 0.24 pmol/mg protein). No difference in [3H]glutamate binding site number was observed in pineal glands obtained from animals sacrificed during the middle of the light and dark periods. These data suggest a possible modulatory role for a glutamate binding site in pineal g

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00483.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract:Plasma concentrations of neurohypophysial hormones show clear rhythms over 24 hr which can be suppressed by exposure to constant light, an observation consistent with pineal involvement. A study has therefore been performed on the changes in the hormone levels in the hypothalamus, posterior pituitary, and plasma over 24 hr in control, pinealectomised, and sham pinealectomised animals to determine if the pineal could play a role. Water intake, urine excretion, packed cell volume, plasma osmolality, and electrolytes were also monitored. Pinealectomy had little effect on fluid balance, but after 8 weeks for oxytocin and 2 weeks for vasopressin the morning values (0700–0800) for the circulating concentrations of the hormones were significantly higher in the pinealectomized group compared with the combined sham operated and unoperated groups (pineal intact). By contrast, the pituitary vasopressin was significantly lower in the pinealectomised group. The increase in plasma oxytocin and vasopressin seen over the hours of daylight and accompanying fall in plasma osmolality seen in the pineal intact group were absent in the pinealectomised group. Similarly, the evening fall in pituitary hormone concentrations and increase in hypothalamic hormone content were absent in the pinealectomised animals. After 10 days of exposure to constant light, the fall in plasma osmolality in the pineal‐intact animals over the day was no longer significant; instead a significant increase in plasma osmolality and sodium was seen in the pinealectomised group. Exposure to constant light, while altering the patterns of neurohypophysial activity in the pineal intact group, had little effect on the pinealectomised anim

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1993.tb00484.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY