摘要:

Recent research has justified the presumption that the pineal gland plays a role in the regulation of the gonadal system in mammals. Evidence also exists for androgen receptors in pinealocytes. In the current study, our approach has been to assess the age‐ and sex‐dependent nature of 5α‐DHT receptors in bovine pineal. Although no significant difference was noted between various groups of bulls, cows, peripuberal cows, and calves (male) for pineal weight, the cytoplasmic 5α‐DHT binding site/receptor content in the pineal gland differed significantly. While the males had a low androgen receptor concentration in the pineal (46 fmol/pineal), the females showed the highest (442 fmol/pineal). The peripuberal females without calves and calves (male) presented a 5α‐DHT receptor content in between (225 fmol/pineal; 138 fmol/pineal). When the data were related to unit weight of pineal tissue, the difference still existed. It is suggested that the concentration of cytoplasmic 5α‐DHT receptors reflects the cellular activity and they are inversely related. Further, low cytoplasmic receptors also indicate that most of it is confined to the nuclear sites, as generally suggested for other androgen‐dependent tissues. In the light of these suggestions, it is possible that lowest cytosolic 5α‐DHT receptor concentration in the males, in reality, reflects a higher degree of cellular function and a high concentration of the receptors in the nuclear site. Similarly, the peripuberal cows and calves perhaps have more cellular activity in the pincal than the mature cows. The current investigation, for the first time, by directly estimating the androgen receptors/binding site in the bovine pineal gland, demonstrates the sex‐ an

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00889.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Juvenile maleMicrotus montanuswere examined for the effects of photoperiod, melatonin, and the naturally occurring reproductive stimulant 6‐MBOA on growth and sexual maturation. 6‐MBOA, present in sprouting grass, is an important environmental cue used for the initiation of reproduction in natural populations of this species. Long photoperiod (16:8) was stimulatory to body, testes, and seminal vesicle growth, while short photoperiod (8:16) inhibited these parameters. The pineal hormone melatonin, administered via daily afternoon injections (5 μg), was also inhibitory to all of the above parameters as well as to serum testosterone. 6‐MBOA, administered via injection (0.0001–100 μg) or dietary means (0.1 or 1.0 μg/gm unsifted chow), appeared unable to augment the rate of maturation in long‐photoperiod‐stimulated animals. When short‐photoperiod animals were treated with high doses of the compound (100 μg injected or 1.0 μg/gm sifted chow), body and gonadal growth was inhibited to a greater extent than when animals were exposed to short photoperiod alone, and serum LH was reduced. Lower doses of the compound had no effect. Melatonin‐treated animals experienced less maturational inhibition when simultaneously given a low dose of 6‐MBOA‐coated chow (1.0 μg/gm unsifted chow). A higher dose of 6‐MBOA (1.0 μg/gm sifted chow) was ineffective in preventing the response to melatonin. These results indicate that 1) maleM. montanusutilize photoperiod, rather than 6‐MBOA, as a primary environmental cue, 2) high doses of 6‐MBOA can be inhibitory under short photoperiod, 3) juvenile male voles are highly sensitive to the inhibitory effects of exogenously administered melatonin, and 4) 6‐MBOA can partially prevent the inhibitory effects of melaton

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00890.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The purpose of this study was to test the effects of recombinant rat interferon‐γ (IFN‐γ) on rat pineal function in orgran culture. The glands were pre‐incubated with IFN‐γ (50, 100, and 1,000 antiviral units/ml) for two hours, followed by a stimulation with isoproterenol (ISO, 10‐6M) (in the presence of IFN‐γ) for an additional three hours. The effect of IFN‐γ alone on the pineal function was also tested by adding another group incubated with IFN‐γ (1,000 antiviral units/ml) without ISO stimulation. The following parameters were estimated at the end of the incubation: the activities of N‐acetyltransferase (NAT) and hydroxyindole‐O‐methyltransferase (HIOMT), the levels of melatonin, 5‐hydroxytryptophan (5HTP), 5‐hydroxytryptamine (5HT), and 5‐hydroxyindole acetic acid (5HIAA), and the 5HT/5HIAA ratio. IFN‐γ had no effect on either NAT or HIOMT activities in the pineal glands. At 50 units/ml, IFN‐γ increased the melatonin content over the ISO‐stimulated level in the pineal but not in the media. IFN‐γ alone, at 1,000 units/ml, also increased the melatonin content significantly over the control level. The levels of 5HTP and 5HIAA were significantly suppressed by IFN‐γ, either alone or in combination with ISO. The level of 5HT was not altered by any of the treatments. The 5HT/5HIAA ratio was significantly increased by IFN‐γ, either when given alone or when given in combination with ISO. The results suggest that IFN‐γ enhances melatonin production in the pineal gland by suppressing the oxidative deamination of 5HT to 5HIAA and shunting

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00891.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The pineal organ of the frog,Rana esculentaandR. temporariawas studied by opsin immunocytochemistry using two polyclonal antibovine rhodopsin and the monoclonal antichicken opsin antibodies OS‐2 (detecting blue and green pigments) and COS‐1 (detecting green and red pigments). Four types of photoreceptor cells were distinguished. The large outer segments of the numcrous electron‐dense photoreceptor cells (“large pineal rods”) were immunoreactive with the rhodopsin and OS‐2 antibodies, but reacted weakly with antibody COS‐1. Some electron‐dense photoreceptors with smaller outer segments (“small pineal rods”) were found that were strongly OS‐2‐immunoreactive but moderately rhodopsin‐positive. The long outer segments of the oil droplet containing photoreceptors (“large pineal cones”) were only immunoreactive with the COS‐1 antibodies. The small electron‐lucent photoreceptors (“small pineal cones”) were immunonegative with all the opsin antisera used.These results confirm the presence of the opsin of a (green‐sensitive) rhodopsin in the “large rod” photoreceptors. A blue‐sensitive pigment is supposed to be present in the “small rod” photoreceptors, and a red‐sensitive one in the oil droplet‐containing “large cones”. The opsin‐immunonegative “small cone” is discussed to contain a (UV‐blue?) photopigment that differs essentially in its antigenic sites from the other pigments. The presence of four types of photoreceptors equipped with the opsins of apparently different photopigments strengthens the view that the frog pineal org

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00892.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

An intact pineal gland organ culture technique was developed which utilised radiolabelled tryptophan as the indolic precursor and two‐dimensional thin‐layer chromatography to separate the various indole metabolites produced. The method was capable of reproducibly separating and quantitating all tryptophan metabolites except 5‐methoxytryptophan which co‐chromatographed with tryptophan in all the solvent systems evaluated. Noradrenergic stimulation of cultured pineals led to a predictable increase in N‐acetyl‐serotonin and melatonin production, suggesting that the method was useful for biochemical and pharmacological studies on the pineal gland. Similarly evaluation of the results revealed that a strong linearity existed between N‐acetylserotonin and melatonin production and between actual and theoretical methylation as previously reported, again verifying the usefulness of the met

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00893.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Experimental studies have suggested that the pineal hormone melatonin, in addition to its documented antineoplastic action, plays a role in the physiological regulation of blood cell proliferation. Based on these data, we evaluated the clinical effects of melatonin therapy in patients with myelodysplastic syndrome (MDS) secondary to cancer chemotherapy for primary neoplasms. The study was carried out on six patients, and melatonin was given orally at a dose of 20 mg/daily, following a schedule prepared to reproduce the circadian rhythm of the pineal hormone. A transient improvement in platelet and neutrophil count was achieved in two of five patients with thrombocytopenia and in two of four patients with neutropenia before therapy, respectively, while no effect was seen on hemoglobin concentration. Mean survival time was 12.5 months, and a long survival, greater than 30 months, was achieved in two of six patients. These preliminary results seem to suggest that melatonin may have a role in the treatment of MDS induced by previous cancer chemotherapy.

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00894.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Previous studies on the ultrastructure of the horse pineal gland did not report the presence of “synaptic” ribbons, functionally enigmatic pinealocyte organelles regularly occurring in other mammalian species. The aim of the present study was to reinvestigate the horse pinealocyte in this respect. Careful investigations here reported allowed detection of “synaptic” ribbons in the pinealocytes of all the examined animals, although in a relatively low number (5.4 ± 2.0 per 20,000 μ2of pineal tissue; mean ± SD). The ultrastructure of “synaptic” ribbons in pinealocytes of the horse resembles closely that observed in other mam

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00895.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

It has been reported that mammalian pineal activity is influenced by reproductive hormones. However, even though a relationship between serum estrogen levels and pineal indole metabolism is well documented, little is known about other pineal components. Among peptides, arginine vasopressin (AVP) has been identified in the pineal gland of several species. In the present work, variations of immunoreactive (IR)‐AVP in the rat pineal during the estrous cycle were studied by radioimmunoassay. Pineal IR‐AVP levels increased significantly at the proestrus afternoon, and returned to basal levels by the end of estrus. These variations were partially related to those of serum estradiol concentration. Although the functional role of AVP in the rat pineal has not been clearly elucidated, these findings provide an additional indication that it might be involved in the reproductive function of the female

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00896.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Lanthanum hydroxide together with a fixative solution was injected into the third ventricle of the viscacha. The tracer penetrated freely into the pineal gland demonstrating an extensive network of intercommunicating intercellular spaces. Numerous gap junctions were observed indicating that they are the predominant interparenchymal contacts. The capillaries were characterized by non‐fenestrated endothelial cells lining a moderate‐sized perivascular space. Precipitates of lanthanum hydroxide were found in the basal membranes of the perivascular and interendothelial spaces, but not in the vascular lumina. The tracer stopped at tight junctions; these constitute a barrier between the pinealocytes and the blood compartment. Active micropinocytosis observed in the capillary walls suggests a transendothelial transp

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1990.tb00897.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY