DigitalUM :: Browsing by Subject "Pineal gland"

Browsing by Subject "Pineal gland"

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Open Access
An immunocytochemical study of effects of light deprivation on prolactin cells in the adenohypophysis of the golden hamster
(Murcia : F. Hernández, 1991) Seu-Mei Wang; Chuen-Lan Liu
Population ratio and morphology of prolactin cells were studied by employing immunohistochemical methods in the adenohypophysis of normal and experimental golden hamsters of both sexes at 16 weeks of age. Prolactin cells occupied 29% of the total adenohypophyseal cells in the intact males exposed to 141 10 h lightldark schedule. After stimulation of the pineal activity by blinding or exposure of males to continuous darkness for eight weeks, prolactin cells became atrophic and were reduced in population to 17% and 13%, respectively. ~i n e a l e c t om~~r e v e ntot e sdo me extent the effects of the above treatments; thus, prolactin cells constituted 27% in the pinealectomized and blinded hamsters, and 19% in the pinealectomized and darknesstreated group; and their morphology was comparable with that of the intact controls. Prolactin cells in the normal females were apparently larger in size and more numerous as compared with those of the normal males, comprising 47% of cell population in the anterior pituitary. In response to light deprivation, prolactin cells were atrophic with a diminished cytoplasm and decreased in cell number as reflected in the population ratio of 27% in the blinded and 21% in the darknesstreated groups. In pinealectomized females combined with blinding or darkness-treatment, prolactin cells contained an abundance of secretory granules in the cytoplasm and maintained the population ratio comparable to that in the intact females. The present study revealed that light deprivation exerts an inhibitory effect on the secretory activity of prolactin cells and also causes hypoplasia of prolactin cells in the hamster adenohypophysis, the effects being mediated by the pineal gland.
Open Access
Cell proliferation in the developing rat pineal gland.A bromodeoxyuridine immunohistochemical study
(Murcia : F. Hernández, 2000) Calvo, J.L.; Boya, J.; Carbonell, A.L.; García-Mauriño, J.E.
The immunohistochemical detection of bromodeoxyuridine (BrdU) was used to study the cell proliferation in the developing rat pineal gland, from the appearance of pineal primordium in the embryonic day 15 (E15) until 30 days after birth. The results showed three different proliferative phases. From E15 to E21, the pineal gland shows a phase of rapid proliferation. The second phase corresponds to the first postnatal week, in which the number of labeled cells per surface unit decreases suddenly to values between 20% to 10% of those of embryonic period. From the second postnatal week onwards, the number of BrdU-positive cells progressively decreases.
Open Access
Cellular proliferation in the rat pineal gland during postnatal development
(Murcia : F. Hernández, 1998) Carvajal, J.C.; Carbajo, S.; Gómez Esteban, M.B.; Alvarez-Morujo, A.J.; Muñoz Barragan, L.
To establish a possible correlation between the rate of cellular proliferation and already documented functional and morphological characteristics of the rat pineal gland during postnatal development, the bromodeoxyuridine labelling method was used to evaluate the fraction of cells at the S phase of the cell cycle in paraffin sections from I-, 7-, 14- and 28-day-old rats. Numerical density, taken as an indirect measure of cell hypertrophy, was also evaluated. During the first week after birth the percentage of S phase-cells in the rat pineal gland sharply decreased from around 9% to 1.3%. A smaller but also significant decrease was found from the 7th to the 14th postnatal day where S phase cells were less than 0.5% of all pineal cells. A very low percentage was also seen in samples from 28-day-old rats. Numerical density, namely, the total number of cells per surface unit of pineal section, decreased from birth to the end of the first month. This decrease was also steeper from birth to the 7th postnatal day than at any other period of the study. These results support the idea that a strong expansion of the cellular population of the rat pineal gland precedes morphological and functional maturation and opens the way to further exploration of the relationship between functional and proliferative responses of the pineal gland.
Open Access
Circadian and seasonal changes of synaptic bodies in different parts of the rabbit pineal gland
(Murcia : F. Hernández, 1999) Martínez Soriano, F.; Hernandez-Gil de Tejadal, T.; Lopez Bigorra, M.; Ballester Carmona, S.; Vollrath, L.
In the mammalian pineal gland, synaptic bodies (SBs) are poorly understood organelles. Previous studies in rabbits have shown that the organelles are rather heterogeneous in shape, are few in number during the day and increase in number at night. No studies are currently available on seasonal changes in this species and it is unknown whether the biological rhythms are identical in the proximal, intermediate and distal parts of the elongated pineal. To this end, a study was made of 84 rabbits kept under natural lighting conditions to examine numerical variations of the different types of SBs in the proximal, intermediate and distal regions of pineal glands procured at different timepoints of a 24- hour cycle and in each of the four annual seasons. In the present study, rod-like, sphere-like, ovoid, rectangular and triangular SB profiles were distinguished; the first two types being the most abundant. In addition to the well-known circadian changes, with low numbers of SB profiles during the day and high numbers at night, we found pronounced season-related differences as well as differences related to pineal regions. In autumn and winter, nighttime SR profile numbers were significantly higher than in spring and summer. With respect to regional differences it was found that the amplitude of the circadian rhythm increased in a proximo-distal direction in the gland. In autumn the strongly enhanced nocturnal increase was restricted to the distal region of the gland, whereas in winter it was seen in both the distal and the intermediate regions. The regional differences are probably related to the fact that the postganglionic sympathetic fibres, which regulate pineal function, enter the gland distally and proceed rostrally to the proximal region. Taken together, the results show that day- and nightlength are structurally coded in the pineal gland by means of SB numbers. Provided the SBs of the mammalian pineal gland are involved in synaptic processes, the results suggest that synaptic processes are enhanced at night as well as in autumn and winter.
Open Access
Circadian and seasonal variations in pineal gland intercellular canaliculi in the white rat
(Murcia : F. Hernández, 1991) Martínez Soriano, F.; Cimas García, C.; Ruíz Torner, A.
Seventy Wistar rats are used to study the changes in pineal intercellular canaliculi over a 21-hour period and for two different photoperiods (pre-autumn, first week of September, and winter, first week of February). The study considers these changes at pineal body, cortical and medullar level separately, and compares the values obtained. The results show variations in canalicular surface at different point times (10:00, 14:00,18:00) and for both photoperiods. The variations are found to favour the cortical layer, and are also observed between nocturna1 and diurnal hours. Canalicular surface to greater during the diurnal hours of both photoperiods. Interesting histological findings are described that suggest an important function of the intercellular canaliculi in pineal gland metabolic exchange.
Open Access
Diencephalic origin of the pineal gland of the chicken embryo
(Murcia : F. Hernández, 1991) Aige-Gil, Vicente; Murillo-Ferrol, Narciso
In the present paper, the diencephalic origin of the chick pineal gland was analyzed by a series of experiments: prosencephalic substitution; in vitro culture of isolated diencephalons; and total or partial excission of the diencephalic roof. The results indicate that the differentiation of the chick pineal gland in the rooof of the third ventricle is not influenced by the neighbouring brain vesicles and is of diencephalic origin. Moreover, in order to obtain chick embryos with pineal agenesia, the whole diencephalic roof has to be removed.
Open Access
Differential light intensity and spectral sensitivities of atlantic salmon, european sea bass and atlantic cod pineal glands ex vivo
(2010) Vera, L.M.; Davie, A.; Taylor, J.F.; Migaud, H.; Fisiología
Photoperiod is perceived by pineal photoreceptors and transduced into rhythmic melatonin signals. These rhythms can be influenced by light intensity and spectral content. In this study we compared the light sensitivity of Atlantic salmon, European sea bass and Atlantic cod by testing ex vivo the effect of different intensities and narrow bandwidth lights on nocturnal melatonin suppression by isolated pineal glands in a flow-through culture system. Using combinations of neutral density and bandpass interference filters we tested a range of light intensities (ranging from 1.22 x 1013 – 3.85 x 106 photons.s-1 .cm-2 ) and three wavelengths of 80 nm width (472, 555 and 661 nm corresponding to blue, green and red, respectively). Results showed clear species specific light intensity and spectral sensitivities, with cod being from 100 to 1000 times more sensitive than sea bass and salmon. Regarding the influence of spectrum, red light was less efficient on suppressing melatonin than blue and green in salmon but results were not as clear in the two other species studied. Finally, the first evidence of relative photoreception in teleosts was obtained in cod suggesting that the definition of illuminance thresholds (day/night perception) would depend on the day intensity. Indeed, a single order of magnitude increase or decrease in day intensity was shown to elicit a significant shift in the intensity response curve of night-time melatonin suppression. Taken together, this study demonstrated species specific light intensity and spectral sensitivities within temperate teleosts.
Open Access
Effects of light deprivation on prolactin cells in golden hamsters: an immunoelectron microscopic study
(Murcia : F. Hernández, 1992) Seu-Mei Wang; Jiahn-Chun Wu; Chia-Man Lue; An-I Tsai; Wen-Ping Chen; Huai-San Lin
In the golden hamster light deprivation has been shown to induce gonadal regression and reduction of pituitary and plasma levels of prolactin (PRL). In the present study we examined changes in morphology and population ratios of three types of PRL cells 8 weeks after light deprivation, by means of blinding or exposure of hamsters to continuous darkness. In the pituitary of intact hamsters of either sex, which were entrained to a 14-h light: 10-h dark cycle, Type C cells with large secrtetory granules were the most numerous and Type A with smalier granules the least. After light deprivation the pituitary was found to contain remarkably atrophic PRL cells and showed a profound change in population ratio of PRL cell types, Le., Type A cells prevailed over the other two types. Pituitary glands from light-deprived and concurrently pinealectomized hamsters exhibited structures and a population ratio of three types of PRL cells similar to those from intact animals. It is suggested that small-granule-containing PRL cells represent an inactive stage of PRL cells, whereas medium- and large-granule-containing cells are functionally active cells. The atrophy of PRL cells can account for the decreased pituitary leve1 of PRL in light-deprived hamsters reported previously.
Open Access
Effects of white light on the pineal gland of the chick embryo
(Murcia : F. Hernández, 1992) Aige-Gil, Vicente; Murillo-Ferrol, Narciso
Chick embryos were directly exposed to a source of white light during incubation and sacrificed before hatching. The light caused a number of teratological effects such as high mortality, delay in development, celosomy, hepatomegaly, auricular dilation and micrognatia. The pineal gland of the illuminated embryos showed an increase in number and size of the intracytoplasmic lipid droplets of the follicular pinealocytes. These findings suggest that the pineal gland of the chick embryo is sensitive to light.
Open Access
Embryonic development of the bovine pineal gland (Bos taurus) during prenatal life (30 to 135 days of gestation)
(Murcia : F. Hernández, 2005) Regodón, S.; Roncero, V.
The ontogenesis of the pineal gland of 30 bovine embryos (Bos taurus) has been analysed from 30 until 135 days of gestation by means of optical microscopy and immunohistochemical techniques. For this study, the specimens were grouped into three stages in accordance with the most relevant histological characteristics: Stage 1 (30 to 64 days of prenatal development); Stage 2 (70 to 90 days) and Stage 3 (106 to 135 days). In the cow, it is from 30 days of gestation that the first glandular outline becomes differentiated from the diencephalic ependyma of the third ventricle. This differentiation includes the phenomena of proliferation and multiplication of the ependymal cells that form the epithelium of the pineal outline in development. At 82 days of intrauterine life, in the interior of the pineal parenchyma, we witnessed some incipient pseudoglandular structures that at 135 days were well differentiated. The pineal parenchyma displays a cytology made up of two cellular types of structurally distinct characteristics: pinealoblasts and interstitial cells. Both cellular types begin differentiation at 70 days of embryonic development, the pinealoblasts being greater in number than the interstitial cells. The glandular stroma is formed from the capsular, trabecular and the perivascular connective tissue, filling the interparenchymal space. A dense network of capillaries, which drive across the trabecular connective tissue towards the central glandular zone where their density increases and their calibre is reduced, complete the glandular structure. GFAP positive cells were observed in the embryonic pineal parenchyma in stage 3. At 135 days of gestation, NPY positive fibers entered the pineal gland through the pineal capsule occupying a perivascular localization. Morphological studies of this nature are vital for future use as parameters, indicative of the functional activity of the bovine pineal gland during embryonic development.
Open Access
Histomorphogenesis and immunohistochemical study of the bovine pineal gland (Bos taurus) during prenatal development (160 days of gestation to birth)
(Murcia : F. Hernández, 2006) Regodón, S.; Pozo, D.; Roncero, V.
The ontogenesis of the pineal gland of 20 bovine embryos (Bos taurus) has been analysed from 160 days of gestation to birth by means of optical microscopy and immunohistochemical techniques. For this study, the specimens were grouped into two stage in accordance with the most relevant histological characteristics: Stage 1 (160 to 200 days of prenatal development) and Stage 2 (220 days of prenatal development to birth). At 160 days of gestation some rounded structures with a central lumen, which we refer to as glandular rosettes, begin differentiation from the epithelium of the pineal recess, experiencing an extraordinary increase in number and size at 200 days of intrauterine life. In the interior of the pineal parenchyma we observed some morphologically rounded cells with oval euchromatic nuclei and a well-differentiated nucleolus that we refer to as the pinealoblasts. We also observed other cells characterised by the presence of low cytoplasm and rounded and highly stained nuclei that we refer to as the interstitial cells. The glandular stroma is formed from the capsular, trabecular, and perivascular connective tissue as well as from the reticular network that comes from the cellular processes of the interstitial cells. The blood vessels, at 240 of gestation, show wellformed walls where the endothelial cells stand out. At 160 days of gestation we witnessed some cells with small, dense, oval nuclei, positive to the glial fibrillary acidic protein (GFAP). At this age NPY positive fibres were detected, distributed around the blood vessels and among the pinealoblasts. We conclude by clarifying that the changes detected in the morphology as well as in the number and size of glandular rosettes appear to be related to the functional activity of the pineal gland during embryonic development.
Open Access
Immunohistochemical localization of glial fibrillary acidic protein (GFAP) in rat pineal stalk astrocytes
(Murcia : F. Hernández, 1992) López-Muñoz, F.; Boya, J.; Marín, F.
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Open Access
Influence of light-dark, seasonal and lunar cycles on serum melatonin levels and synaptic bodies number of the pineal gland of the rat
(Murcia : F. Hernández, 2002) Martínez Soriano, F.; Ruíz Torner, A.; Armañanzas, E.; Valverde-Navarro, A.A.
Synaptic bodies (SB) are ultrastructural o rganelles observed in the pinealocytes of mammals. According to its shape, they have been classified into synaptic ribbons (SR), synaptic spherules (SS), and intermediate synaptic bodies (ISB). They have been related to the melatonin regulation and production mechanisms of the pineal gland. Circadian and circannual fluctuations of both melatonin and SB have been reported. The possibility that other external factors, apart from light-dark or seasonal cycles, might influence pineal function has been suggested. We studied the evolution of the number of SB and serum melatonin levels not only during light-dark and seasonal phases but also during lunar cycles. Forty male wistar rats were used. Experiment was first carried out in winter and repeated identically in spring. Each season, one group of animals was killed during the new-moon days and a second group during the full-moon days: half of both groups in the photophase and the other half in the scotophase. The number of SB was measured at electron microscopic level whereas serum melatonin levels were determined by radioimmunoassay techniques. Main results showed that SR number and serum melatonin levels were higher during scotophases, winter and fullmoon days. The SS only showed a light predominance during winter, whereas predominance of the ISB was found only during the scotophases. These results support the influence of the photophasic factors on the SR and ISB variations. In the case of the SS the influence of the lunar cycles is always dependent on the other factors. F i n a l l y, the serum level of melatonin is clearly influenced by the photophasic rhythms and the seasonal periods but not by the lunar cycles.
Open Access
Influence of light-dark, seasonal and lunar cycles on the nuclear size of the pinealocytes of the rat
(Murcia : F. Hernández, 2002) Martínez Soriano, F.; Armañanzas, E.; Ruíz Torner, A.; Valverde-Navarro, A.A.
Morphological and physiological studies suggest a possible division of the pineal parenchyma into an external or “cortical” and another central or “medullar” layer. We have studied the possible influence of the light/dark, seasonal and lunar cycles on the nuclear size of the pinealocytes of the rat in both the hypothetical “cortical” and “medullar” layers. Forty male Wistar rats were used. Experiment was carried out in two seasons, winter and spring, two lunar phases, full moon and new moon, and the two circadian phases, photophase and scotophase. The nuclear volume of the pinealocytes, calculated from the Jacobj’s formula, was the karyometric parameter used as measurement of the nuclear size. Main results showed that nuclear volume of the cortical pinealocytes was greater than that of the medullar pinealocytes only during the photophases of winter new-moon days and spring full moon days, whereas in all the remaining situations, the greater nuclear sizes were found in the pinealocytes of the medullar layer. These results support the existence of independent morphological variations of the pinealocyte in the central and peripheral zones of the pineal gland.
Open Access
Intrinsically synthesized melatonin in mitochondria and factors controlling its production
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Reiter, Russel J.; Sharma, Ramaswamy N; Almieda Chuffa, Luiz Gustavo de; Silva, Danilo Grunig Humberto da Silva; Rosales Corral, Sergio
The percentage of the total amount of melatonin produced in vertebrates that comes from the pineal is small (likely <5%) but, nevertheless, functionally highly noteworthy. The significance of pineal melatonin is that it is secreted cyclically such that it has a critical function in influencing not only the suprachiasmatic nucleus but clock genes that reside in perhaps every cell throughout the organism. Extrapineal melatonin, which may be synthesized in the mitochondria of all other cells in much larger amounts than that in the pineal gland has a different function than that derived from the pineal gland. Its synthesis is not circadian and it is not directly impacted by the photoperiodic environment. Also, melatonin from the extrapineal sites is not normally secreted into the blood stream; rather, it acts locally in its cell of synthesis or, possibly via paracrine mechanisms, on immediately adjacent cells. The functions of extrapineal melatonin include central roles in maintaining molecular and redox homeostasis and actions in resisting pathological processes due to its ability to directly or indirectly detoxify free radicals. The vast majority of organisms that exist on Earth lack a pineal gland so pineal-derived melatonin is unique to vertebrates. Evidence suggests that all invertebrates, protists and plants synthesized melatonin and they have no pineal homolog; thus, the production of melatonin by extrapineal cells in vertebrates should not be unexpected. While the factors that control pineal melatonin synthesis are well documented, the processes that regulate extrapineal melatonin production are undefined.
Open Access
Melatonin, experimental basis for a possible application in breast cancer prevention and treatment
(Murcia : F. Hernández, 2000) Cos, S.; Sánchez Barceló, E. J.
The role of the pineal as an oncostatic gland has been studied in animal models of tumorigenesis, especially on those concerning the mammary gland. The general conclusion is that experimental manipulations activating pineal gland, or the administration of melatonin, reduce the incidence and growth rate of chemically-induced murine mammary tumors, while pinealectomy or situations which implicate a reduction of melatonin production usually stimulate mammary carcinogenesis. The direct actions of melatonin on mammary tumors have been suggested because of its ability to inhibit, at physiological doses (InM), the in vitro proliferation of MCF-7 human breast cancer cells. In this article we review the outstanding findings related to melatonin actions on mammary which, taken together, support a possible usefulnes of this indoleamine in the prevention and treatment of mammary gland malignancy.
Open Access
Nitric oxide synthase in the pineal gland
(Murcia : F. Hernández, 1996) Lopez-Figueroa, M.O.; Moller, M.
The recent discovery of nitric oxide (NO) as a biological messenger molecule with unique characteristics has opened a new field in pineal research. This free radical gas is synthesized by the enzyme nitric oxide synthase (NOS) from L-arginine. The activation of adrenoreceptors in the membrane of the pinealocytes mediates the increase in NO through a mechanism that involves G proteins. In the pinealocyte, NO stimulates guanylyl cyclase resulting in an increased intracellular content of cGMP. The role of cGMP in pineal metabolism, however, is still enigmatic Using enzyme histochemistry and immunohistochemistry, the presence of NOS has been confirmed in the pineal gland of some species. In the rat and especially in the sheep, NOS is located in nerve fibres innervating the gland. These nerve fibres also contain the neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI), and are probably of parasympathetic origin. In cell cultures and tissue sections NOS immunoreactivity has been shown to be present in pinealocytes of the rat and bovine but not in the sheep. Finally, NOS is also present in the endothelial cells of the blood vessels of the pineal gland. Accordingly, in the mammalian pineal gland, NO is synthesized in both presynaptic nerve fibers and pinealocytes, as well as in blood vessels. However, the anatomical location of NO synthesis varies considerably among species. NO released in the pineal gland, might influence both the pineal metabolism and the blood flow of the gland.
Open Access
Pineal gland in rats with 7,12-dimethylbenz (a) anthracene-induced mammary tumors subjected to manipulations known as enhancers of pineal actions
(Murcia : F. Hernández, 1989) Cos, S.; Bardasano, J. L.; Mediavilla, M. D.; Sánchez Barceló, E. J.
The ultrastructure of pinealocytes was studied in rats with 7,17-dimethylbenz (a) anthraceneinduced manimary tumors which were subjected to experimental manipulations known as enhancers of pineal actions (anosmia, underfeeding or cold exposure). In these aniinals we found: (1) - more nuclei with deep nuclear invaginations; (11) - a large number of cytoplasmic organelles, including lipid droplets. myeloid bodies, synaptic ribbons and lysosomes; (111) - numerous degenerative changes. In general, we found an increase in structural features related to pineal photoneuroendocrine activity. Our results indicate that pineal-dependent inhibition of neoplastic growth induced by these experimental manipulations, previously reported, can be mediated through an increase in pineal metabolic activity.
Open Access
Postnatal development of female sheep pineal gland under natural inhibitory photoperiods: an immunocytochemical and physiological (melatonin concentration) study
(Murcia : F. Hernández, 2003) Redondo, E.; Regodón, S.; Masot, A.J.; Gázquez, A.; Franco, A.
The purpose of this study was to determine structural and immunocytochemical changes taking place during the day and at night in developing sheep pineal gland under natural non-stimulatory photoperiods (summer solstice). Additionally, the diurnal cycle of plasma melatonin levels was charted and differences between diurnal and nocturnal pineal melatonin concentrations were analyzed. 36 ewes of three different ages were examined: infants (1-6 months old), pubertal and early fertile age (9-24 months old) and adults (36-60 months old). Plasma and pineal gland melatonin levels were higher in pubertal sheep than in infants or adults. Pubertal sheep pineal glands were also heavier, contained a larger number of pinealocytes and interstitial cells and displayed more evident innervation and vascularisation than infants or adults. There was no difference in the number of pinealocytes and interstitial cells between animals killed during daylight or at night. Gland weight, pinealocyte nuclear profile areas and plasma melatonin concentrations were all significantly higher at night than during the day.
Open Access
Postnatal development of the dog pineal gland. Light microscopy
(Murcia : F. Hernández, 1990) Calvo, J.L.; Boya, J.; García-Mauriño, A.; López Carbonell, A.
The light microscopical morphology of the dog pineal gland from the first postnatal day to maturity is described. In the first postnatal week, the pineal parenchyma shows immature cells and many mitotic figures. In this week, pigmented cells are obsemed for the first time, both in the pineal gland and in extrapineal nodules. Throughout the second week, the pineal parenchyma shows a cordonal pattern that disappears progressively in the following stages. From the 20-30th day onward, it is feasible to discern the cell types characteristic for the adult pineal gland. In the adult animals, the length of the pineal gland axes almost quadruplies that of the pineal gland in neonatal stages. The light microscopical features of the adult dog pineal gland are also described.