Current status of pineal peptides

Effect of delta-sleep inducing peptide-containing preparation Deltaran on biomarkers of aging, life span and spontaneous tumor incidence in female SHR mice

From the age of 3 months until their natural deaths, female Swiss-derived SHR mice were subcutaneously injected 5 consecutive days every month with 0.1 ml of normal saline (control) or with 2.5 microg/mouse (approximately 100 microg/kg) of delta-sleep inducing peptide (DSIP, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) as the preparation Deltaran solved in 0.1 ml of saline. There were 54 mice in each group. The results of this study show that the treatment with Deltaran did not influence food consumption, but decreased the body weight of mice; it slowed down the age-related switching-off of estrous function; it decreased by 22.6% the frequency of chromosome aberrations in bone marrow cells; it did not influence mean life span; and it increased by 17.1% life span of the last 10% of the survivors and by 24.1% maximum life span in comparison with the control group. We also found that treatment with Deltaran significantly decreased total spontaneous tumor incidence (by 2.6-fold), mainly mammary carcinomas and leukemias in mice as compared with the control group. This is the first report on geroprotector and anticarcinogenic effect of DSIP-containing preparation Deltaran.

Effects of the pineal gland and melatonin on the metabolism of oocytes in vitro and on ovulation in Bufo arenarum

The pineal gland and the hormone melatonin appear to be responsible to some extent for the metabolic behaviour of Bufo arenarum oocytes during the winter. This assumption is supported by the observation that, in isolated mitochondria, both elements stimulate the rate of oxidation of citrate and inhibit that of fumarate, thus raising the oxidizing ratio that relates these parameters (C/F) to values close to or above 1, which is characteristic of these animals in winter. The sensitivity of oocytes to melatonin, in terms of the C/F ratio, varies throughout the year. It is maximal in fall and early winter at a dose of 1.8 micrograms/ml after 30 min treatment, minimal or nonexistent in late winter, and it increases gradually during the spring and summer. The response of oocytes to melatonin is more significant if the animals have been previously injected with a homogenate of homologous hypophysis. A direct metabolic effect of melatonin on oocytes was observed when coelomic oocytes, without follicle cells, responded to hormonal treatment. Both an extract of pineal gland and melatonin inhibit in vitro ovulation, the inhibitory effect of the extract being greater than that of the hormone.

Morphofunctional aspects of the mammalian pineal gland

The primary aim of this review is to present the current state of knowledge of the ultrastructure of the mammalian pineal gland, with emphasis on its functional aspects. Basic ultrastructural features of the mammalian pinealocytes are presented with special attention paid to ultrastructural aspects of pineal secretion.

Isolation and structure elucidation of bovine pineal arginine vasopressin: arginine vasotocin not identified

A large number of reports have demonstrated the presence of neurohypophysial hormone-like peptides in mammalian pineal glands and an antigonadotropic function has been ascribed to pineal arginine vasotocin (AVT). We have undertaken large scale purification of bovine pineal neurohypophysial hormone-like substances which demonstrate mouse mammary milk-ejection activity (ME-activity) in vitro. Peptides with ME-activity were extracted from more than 5 kg of bovine pineal glands. ME-activity containing peptides were found in both high (Mr approximately 10,000-15,000) and low (Mr approximately 500-1000) Mr species from Sephadex G-25 chromatography of 0.2 N acetic acid extracts. After ultrafiltration in 5% formic acid, the neurohypophysial hormone-like peptides were localized to an ultrafiltration Mr 500-1000 retentate. A homogeneous peptide, which shared an identical retention time (RT) and amino acid sequence with synthetic 8-arginine vasopressin (AVP), was isolated by serial semipreparative high performance liquid chromatography. On the other hand, the non-mammalian nonapeptide AVT was not identified.

Neonatal melatonin administration advances rat vaginal opening and disrupts estrous cyclicity and estrogen-dependent regulatory mechanisms of luteinizing hormone and prolactin

Melatonin (100 micrograms/rat) was administered to female rats on day 5 of life, 3 hours prior to the onset of darkness or at 12:00 hours. Melatonin administration induced precocious puberty in both cases, as indicated by the advance of the time of the vaginal opening and the appearance of the first estrous smear as compared with controls (P less than 0.01), together with an increase in the number of estrous smears (P less than 0.05) and a reduction in the number of diestrous smears (P less than 0.05). Decreased serum prolactin levels were observed on day 21 of age (P less than 0.05) in melatonin-treated rats with both of the melatonin injection times as compared with controls. No differences were apparent in basal luteinizing hormone (LH) levels either at 30 or at 60 days of age comparing melatonin- and vehicle-treated rats with either of the scheduled melatonin injection times. As to serum follicle-stimulating levels (FSH) levels, there was a marked decrease in circulating FSH levels in melatonin-treated rats in both cases on days 21, 30, and 45 (P less than 0.05) as compared with controls. A marked increase of serum prolactin at both 48 and 55 hours after estradiol benzoate (EB) administration was detected in 30-day-old melatonin-treated rats as compared with controls (P less than 0.05 for both points). Also, an increased responsiveness of prolactin to EB was found on the first day post-administration. At 60 days of age, an increase in prolactin responses to EB was observed on the first day post-administration (31 and 48 hours after, (P less than 0.01), whereas no differences were detected at any other studied time. The LH burst that occurs 31 hours after EB administration in 30-day-old rats was decreased in melatonin-treated animals as compared with controls (P less than 0.05). In 60-day-old melatonin-treated rats, a marked increase in the LH response to EB administration, 31 hours after injection (P less than 0.01), was observed. These data suggest that neonatal melatonin administration in pharmacological amounts induces precocious puberty as measured by vaginal opening and, furthermore, it advances the appearance of the first estrous smear with age-dependent modifications of estrous cyclicity and prolactin and LH responses to EB.

Intracranial germ-cell tumors: natural history and pathogenesis

The natural history of primary intracranial germ-cell tumors (GCT's) is defined from 389 previously published cases, of which 65% were germinomas, 18% teratomas, 5% embryonal carcinomas, 7% endodermal sinus tumors, and 5% choriocarcinomas. Intracranial GCT's display specificity in site of origin. Ninety-five percent arise along the midline from the suprasellar cistern (37%) to the pineal gland (48%), and an additional 6% involve both sites. The majority of germinomas (57%) arise in the suprasellar cistern, while most nongerminomatous GCT's (68%) preferentially involve the pineal gland (p less than 0.0001). The age distribution of afflicted patients is unimodal, centering with an abrupt surge in frequency in the early pubertal years; 68% of patients are diagnosed between 10 and 21 years of age. Nongerminomatous GCT's demonstrate an earlier age of onset than do germinomas (p less than 0.0001). Prolonged symptomatic intervals prior to diagnosis are common in germinomas (p = 0.0007), in suprasellar GCT's (p = 0.001), and among females (p = 0.02). Parasellar germinomas commonly present with diabetes insipidus, visual field defects, and hypothalamic-pituitary failure. Nongerminomatous GCT's present as posterior third ventricular masses with hydrocephalus and midbrain compression. Germ-cell tumors may infiltrate the hypothalamus (11%), or disseminate to involve the third ventricle (22%) and spinal cord (10%). Among a subpopulation of 263 conventionally treated patients, two factors were of prognostic significance: 1) histological diagnosis; germinomas were associated with significantly longer survival than nongerminomatous GCT's (p less than 0.0001); and 2) staging of the extent of disease; this emphasizes the ominous character of involvement of the hypothalamus (p = 0.0002), third ventricle (p = 0.02), or spinal cord (p = 0.01). Specific recommendations regarding the necessity of histological diagnosis and staging of the extent of disease are made in light of modern chemotherapeutic advances. The pathogenesis of GCT's may be revealed by their specificity of origin within the positive (suprasellar cistern-suprachiasmatic nucleus) and negative (pineal) regulatory centers for gonadotropin secretion within the diencephalon. The abrupt rise in age distribution at 10 to 12 years suggests that the neuroendocrine events of puberty are an "activating" influence in the malignant expression of these embryonal tumors.

Arginine vasotocin (AVT), an alleged hormone of the mammalian pineal gland

Arginine vasotocin has been proposed as a hormone of the mammalian pineal gland. This claim is largely based on biological and immunological results, although some chemical evidence has also been provided. Yet, more and more researchers have recently disclaimed the presence of this nonapeptide in mammalian tissue. The currently available evidence is critically reviewed exposing the dispute as a real one urgently requiring final settlement.

Inclusion bodies in pinealocytes of the cotton rat (Sigmodon hispidus). An ultrastructural study and X-ray microanalysis

Pinealocytes of the cotton rat (Sigmodon hispidus) often contain large (2-6 micron diameter) intracytoplasmic inclusions, the function of which is not known. These inclusions may represent nucleolus-like bodies, mineral deposits, secretory products or viral inclusions. In this study these inclusions were classified as type A, B or C inclusions based on the amount of electron-dense material interspersed within the finely granular material comprising the bulk of these inclusions. Each type of inclusion was analyzed by X-ray microanalysis and enzymatic proteinaceous digestion. X-ray microanalysis of these inclusions differed both quantitatively and semiquantitatively from that of human or gerbil pineal concretions, the latter two of which are extracellular deposits. Pronase, a proteolytic enzyme, digested the electron-dense material only after longer times of tissue exposure to this enzyme in contrast to the easily digested, finely granular matrix-like material of these inclusions. Such intrapinealocytic inclusions have only been observed in the cotton rat. Their functional significance remains unknown.

Alterations in the spontaneous activity of cells in the guinea pig pineal gland and visual system produced by pineal indoles

The indoles serotonin (SER), melatonin (MEL), 5-methoxytryptophol (5-MTL) and 5-hydroxytryptophol (5-HTL) were administered during daytime microelectrophoretically to 240 cells in the pineal gland of the guniea-pig. The action of SER and 5-HTL was predominantly depressant on the electrical activity, MEL and 5-MTL caused an excitation in most of the units. Although MEL and 5-MTL caused fairly similar reactions on average, they appear to act on different cells. The effects of microelectrophoretically applied MEL and 5-MTL on the spontaneous or evoked activity in the visual system (retinal ganglion cells, optic tract, lateral lateral geniculate body, superior colliculus) of the guinea-pig were also investigated. Of the 76 cells tested in the visual system 25 of the ON- and OFF-cells increased the rate of discharge when the two indoles were applied. Cells in the optic layer of the superior colliculus showed no measurable response to the application of the two substances. 5-HTL caused no effect on cells in the visual system.

Pinealectomy advances the time of development of steroid feedback on luteinizing hormone release in immature female rats

The effect of pinealectomy (Px) on the development of steroid positive feedback on luteinizing hormone (LH) release was examined in female rats subjected to surgery at 10 days of age. Estradiol-progesterone injection decreased serum LH in sham Px or intact controls younger than 20 days, while a significant LH release was found at day 22; Px rats showed a steroid-induced LH depression only at day 16, a positive feedback being detectable at day 20, 2 days earlier than in sham Px or intact rats. Daily injections of 10-50 micrograms melatonin to intact rats disrupted the LH negative feedback response at day 20, and diminished steroid-induced LH release at day 24.

The pineal gland of the mole (Talpa europaea L.). VII. Activity of hydroxyindole-O-methyltransferase (HIOMT) in the formation of 5-methoxytryptophan, 5-methoxytryptamine, 5-methoxyindole-3-acetic acid, 5-methoxytryptophol and melantonin in the eyes and the pineal gland

Using a method in which no substrate is added to the incubation medium, the capacity of HIOMT to synthesize 5-methoxytryptophan, 5-methoxytryptamine, 5-methoxyindole-3-acetic acid, 5-methoxytryptophol and melatonin has been determined in the pineal and the eyes of the mole, a mammal having an atrophied visual system. The results demonstrate that the indoleamine metabolism in the retina is similar to the indoleamine metabolism in the pineal. Moreover, in all animals studied both eyes together synthesize 2 to 30 times more of 5-methoxyindoles than the pineal, a result which proves again that the pineal is not the only and not always the most important source of 5-methoxyindoles. With the exception of 5-methoxyindole-3-acetic acid, the synthesis of which is practically neglectable, the production of all other 5-methoxyindoles in the pineal as well as in the retinae is always larger than that of melatonin. In the pineal, 5-methoxytryptophan, for example, is synthesized in a quantity which is 60 to 170 times larger than that of melatonin, while in the retinae the synthesized amount of 5-methoxytryptophan is even 60 to 1000 times larger than that of melatonin.

Circadian rhythmicity of the activity of hydroxyindole-O-methyl transferase (HIOMT) in the formation of melatonin and 5-methoxytryptophol in the pineal, retina, and harderian gland of the golden hamster

The day and night rhythms in the activity of HIOMT in the formation of melatonin of 5-methoxytryptophol have been determined in the pineal, retina and Harderian gland of the adult male golden hamster. In all hamsters used there was no detectable HIOMT activity in the deep pineal. In the superficial pineal HIOMT activity, involved in the synthesis of melatonin (Mel), was observed to be high at the end of the dark period and at the middle of the light period. Considering the HIOMT activity involved in the production of 5-methoxytryptophol (5-MTL), an increase in 5-MTL synthesis was observed only during the light period. Comparing the peak of Mel-production with that of 5-MTL it appears that during the light period the pineal produces more 5-MTL than Mel. In the Harderian glands, the circadian course of HIOMT activity involved in the synthesis of Mel seems to run parallel to that of the enzyme implicated in 5-MTL synthesis, both being stimulated at the end of the dark period. The activity of HIOMT in 5-MTL production is, however, always approximately 2 times higher than for Mel synthesis. In the retina the synthesis of Mel and 5-MTL is not significantly higher during the dark period than during the light period. However, the production of 5-MTL is larger than that of Mel. It appears that (1) with the exception of the end of the dark period, the extra-pineal synthesis of Mel and 5-MTL is always higher than that in the pineal; (2) the carcadian synthesis of 5-methoxyindoles is different in each organ, and (3) in the pineal the carcadian activity of HIOMT involved in 5-MTL formation is different from that of the same enzyme involved in the formation of Mel. The results are discussed.

An interaction between the pineal gland and olfactory deprivation in potentiating the effects of melatonin on gonads, accessory sex organs, and prolactin in male rats

Male rats (25-26 days of age) housed with 14 hours of light per day (lights on 0600--2000 hours) were either olfactory bulbectomized (rendering them anosmic), bulbectomized plus pinealectomized (Pinx), or left intact. On the day following the operations, intact, anosmic, and anosmic-Pinx animals began receiving single, daily afternoon (1700--1800 hours) subcutaneous injections of 50 microgram of melatonin (MEL) for six weeks, while an additional group of intact controls received injections of diluent. At the end of this period, body, anterior pituitary, testicular, and seminal vesicle weights were significantly reduced in intact-MEL-treated animals. Anosmic animals that had been treated with MEL experienced a further, highly significant, 65%, 90%, and 85% depression in testicular, seminal vesicle, and ventral prostate weights, respectively, as compared with intact control and MEL-treated rats. Additionally, both body and anterior pituitary weights were significantly decreased in MEL-treated, anosmic rats. Anosmic-Pinx rats treated with MEL had organ and body weights that were intermediate between those of intact-MEL and anosmic-MEL-treated animals. Pituitary and serum levels of prolactin (Prl) were significantly lower in anosmic-MEL-treated rats than in intact-MEL-treated groups. Similarly, Prl levels were depressed in the anosmic-Pinx rats treated with MEL; however, serum Prl was not statistically lower than in intact or intact-MEL-treated animals. These results indicate that anosmic male rats have an increased sensitivity to antigonadotrophic and Prl-inhibitory effects of MEL. Futhermore, the data suggest that the presence of the pineal gland in anosmic rats is important in permitting anosmia maximally to sensitize the neuroendocrine-reproductive axis to the antigonadotrophic effects of exogenously administered MEL.

The structural organization of the pineal complex in the domestic goose

The light and electron microscopic structure of the pineal complex of the domestic goose was studied. The complex is tubulofollicular but there is no direct connection between the constituent system of ducts and the third ventricle of the brain. Within the pineal, blood vessels accompanied by sympathetic nerve bundles are confined to the connective tissue. Other nerve fibers and occasional nerve cell bodies, however, do occur among the pineal cells. Threee basic pineal cell types were distinguished: (1) elongate epithelial cells which are arranged around follicles and ducts and resemble degenerate photoreceptor cells; (2) intramural supportive cells which are interspersed with elongate epithelial and intramural supportive cells; and (3) small supportive cells which lie between the bases of the elongate epithelial and intramural supportive cells. The follicular structure, vascularization, presence of secretory granules, and the nature of the elongate epithelial cells indicate that the pineal complex is primarily endocrine through a possible photoreceptive function cannot be ignored. Vesicles, 100-300 and 40-100 nm wide, were found with;n nerves and intramural supportive cells. The larger vesicles, present in pineals collected in the night, probably contain peptidic hormones. The smaller vesicles present in both day and night samples probably contain aminergic hormones.

Endocrine regulation of thymic biosynthetic polyamine decarboxylases in adult rat

The activities of ornithine and S-adenosyl-L-methionine decarboxylase were assayed in the thymuses of adult rats killed at 7-day intervals up to 6 wk after either pinealectomy or sham pinealectomy. The absence of the pineal gland markedly influenced the ornithine decarboxylase activity in the thymus, in which the level of the enzyme was decreased permanently by the 4th wk after the operation (P less than 0.05). The time course of the changes in S-adenosyl-L-methionine decarboxylase activity in the thymus during the entire period investigated was also significantly (P less than 0.05) modified by pinealectomy but did not show any stable trend. Adrenalectomy significantly raised (P less than 0.001) for ornithine decarboxylase; P less than 0.01 for S-adenosyl-L-methionine decarboxylase) the basal levels of the thymic biosynthetic polyamine decarboxylases. A pharmacological dose of corticosterone or cortisol produced a rapid and significant decrease in ornithine and S-adenosyl-L-methionine decarboxylase activities (P less than 0.02) in the thymus, whereas the injection of either D-aldosterone or ACTH was ineffective. Therefore, the thymic biosynthetic polyamine decarboxylases that in this organ are known to be located only in the lymphocytes appear to be regulated in opposing ways by the pineal gland and by the adrenal cortex.

The pineal-paraphyseal complex of sea turtles. I. Light microscopic description

The pineal-paraphyseal complex of sea turtles is an impressively large structure which projects dorsally and anteriorly above the prosencephalon. The complex was examined by light microscopy in several age classes of green sea turtles (Chelonia mydas) and from juvenile loggerhead turtles (Caretta caretta). The paraphysis is extensively fused to the distal portion of the pineal body, suggesting an interrelated function for these two tissues. No duct or canal was observed connecting the pineal lumen to the third ventricle. Two pineal cell types are described which appear to correspond to the neuroglial supportive cells and the secretory rudimentary photoreceptor cells of other amniotic vertebrates. A possible luminal secretion in the form of apical protrusions is produced by the latter cell type. No typical photoreceptive outer segments were observed.