bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of pinealectomy on wool growth and wool follicle density in Merino sheep
Authors: McCloghry Elizabeth , Foldes Andrew , Hollis David , Rintoul Allan , Maxwell Colin , Downing Jeff , Baker Peter , Kennedy John , Wynn Peter 
Published: February 2007

Abstract: There is evidence to indicate that pinealectomy may enhance wool growth in the sheep. The aim of this study was to determine the effect of pinealectomy on wool growth and wool follicle density in Merino sheep.Castrated Merino rams (4 months old) were either pinealectomized (P), sham‐pinealectomized (S) or not treated (C). Wool growth on mid‐side patches was measured every 4 weeks and follicle density was monitored in skin biopsies collected before treatment and at regular intervals for 60 weeks. Venous blood samples were taken on each of these occasions for prolactin analysis. Melatonin concentrations were determined in venous blood collected pre‐ and posttreatment from samples taken over a 24‐hr period during the winter solstice.Pre‐ and posttreatment plasma melatonin levels (mean ± SEM) 65 ± 17 and < 13 pg/ml for P, 86 ± 21 and 69 ± 20 pg/ml for S, and 94 ± 41 and 122 ± 37 pg/ml for C, respectively, indicated that the pineal glands had been successfully removed. Wool growth, total follicle density and liveweight (mean ± SEM) did not differ between treatment groups. Measurements at week 60 were 3.9 ± 0.3, 4.1 ± 0.2, and 3.8 ± 0.3 gm clean wool/100 cm2; 66 ± 6, 69 ± 7, and 64 ± 3 follicles/mm2; and 50.4 ± 1.3, 50.8 ± 1.4, and 52.6 ± 1.1 kg liveweight for groups P, S, and C, respectively. There was no difference in plasma prolactin levels between the groups during the experiment (P:179 ± 37, S:183 ± 37, C.189 ± 37 ng/ml), but the expected seasonal prolactin rhythm was absent in all animals. These results indicate that the removal of endogenous pineal hormones by pinealectomy has no effect on wool growth and wool follicle density in Merino lambs.
Pharmacological profile and diurnal rhythmicity of 2‐[125I]‐iodomelatonin binding sites in murine mammary tissue
Authors: Recio J. , Mediavilla M. D. , Cardinali D. P. , Sánchez‐Barceló E. J. 
Published: February 2007

Recio J, Mediavilla MD, Cardinali DP, Sánchez‐Barceló EJ. Pharmacological profile and diurnal rhythmicity of 2‐[125I]‐iodomelatonin binding sites in murine mammary tissue. J. Pineal Res. 1994: 16: 10–17.AbstractRecent studies demonstrated that melatonin treatment decreased the growth of mammary glands in pubertal and pregnant mice. In vitro, melatonin inhibited murine mammary gland growth at μM concentrations and increased it at pM concentrations. Melatonin‐induced changes of cyclic nucleotide synthesis was also demonstrated in mammary gland slices in vitro. The objective of the present study was to assess the possible existence of specific binding sites for melatonin in murine mammary gland by using 2‐[125I]‐iodomelatonin as a probe. The specific binding of 2‐[125I]‐iodomelatonin to murine mammary gland membranes was rapid, saturable, and reversible, showed an affinity in the low nM range, and displayed time, temperature, and pH dependence. Scatchard analysis indicated the existence of a single class of binding sites that exhibited a diurnal rhythmicity in affinity (Kd) and receptor density (Bmax). A maximum in Bmax (267 ± 42 fmol/mg protein) was found at the light period, while affinity was maximal during darkness (Kd= 1.33 ± 0.22 nM). In competition studies dopamine and dopamine‐related agents, as well as 6‐hydroxymelatonin and serotonin, but not melatonin, effectively displaced 2‐[125I]‐iodomelatonin from mammary binding sites. The results demonstrated a specific binding of 2‐[125I]‐iodomelatonin to murine mammary glands, with affinity in the low nM range, and a pharmacological profile that differed from that reported for 2‐[125I]‐iodomelatonin acceptor sites in other tissues.
Melatonin rhythms in Arctic urban residents
Authors: Stokkan K.‐A. , Reiter R. J. 
Published: February 2007

Stokkan K‐A, Reiter RJ. Melatonin rhythms in Arctic urban residents. J. Pineal Res. 1994: 16: 33–36.AbstractThe 24‐hr rhythm of salivary melatonin was measured in persons living in the city of Tromsø (70°N) at the following times of the year: in January at a day length of 2 hr of twilight, in June under continuous sunshine, and in March and September at about 12 hr light and 12 hr darkness. The hormone patterns varied widely between individuals, but, in general, they were consistent within most individuals between the seasons. Highest peak values occurred in January when the mean level was also significantly higher than at any other time of year. The lowest mean levels occurred in June. Although individual rhythms were not always apparent, the mean patterns showed significantly elevated melatonin concentrations during the night at all seasons. The June melatonin peak was similar to that in March and September, but appeared to be phase‐delayed with increased melatonin concentrations from midnight until 0900. It is assumed that the delayed melatonin peak in June may be associated with a tendency among people to shift their activity/rest rhythm and that the pineal sensitivity to light is reduced in the morning in summer.
Distribution of cholinergic and dopaminergic receptors in rainbow trout pineal gland
Authors: Samejima Michikazu , Happe H. Kevin , Murrin L. Charles , Pfeiffer Ronald F. , Ebadi Manuchair 
Published: February 2007

Samejima M, Happe HK, Murrin LC, Pfeiffer RE, Ebadi M. Distribution of cholinergic and dopaminergic receptors in rainbow trout pineal gland. J. Pineal Res. 1994: 16: 37–43.AbstractThe involvement of multiple receptors in modulating the function of the pineal gland was investigated by searching for dopaminergic and cholinergic receptors in trout pineal gland. Dopamine D1 and D2 receptors were measured using [3H]SCH23390 and [3H]spiperone, respectively. Muscarinic and nicotinic cholinergic receptors were measured using quinuclidinyl benzilate ([3H]QNB) and [3H]methylcarbamyl choline, respectively. High‐affinity choline uptake sites were measured using [3H]hemicholinium‐3. The distribution of dopaminergic receptors varied throughout the pineal gland in that the density of D2 receptors, which was higher than that of D1 receptors, was most abundant in the distal region, exhibiting a value of 112 ± 17 fmol/mg tissue. The distribution of both muscarinic and nicotinic receptors was uniform throughout the pineal gland. However, the highest value for the high‐affinity choline transporter (106 ± 17 fmol/mg tissue) occurred in the proximal portion of the trout pineal gland. The results of these studies indicate that the pineal gland should not be viewed as a homogenous tissue possessing identical density of various receptors. Furthermore, these results, along with previous data, are interpreted to suggest that different regions of pineal gland may indeed possess unique functions.
Immunocytochemical localization of basic fibroblast growth factor in the rat pineal gland
Authors: Marin Fernando , Boya Jesús , Calvo José Luis , López‐Muñoz Francisco , Garcia‐Mauriño José Enrique 
Published: February 2007

Marín F, Boya J, Calvo JL, López‐Muñoz F, García‐Mauriño JE. Immunocytochemical localization of basic fibroblast growth factor in the rat pineal gland. J. Pineal Res. 1994: 16: 44–49.AbstractThe immunocytochemical localization of basic fibroblast growth factor (b‐FGF) during the postnatal development of the rat pineal gland was studied using a polyclonal antibody against the fraction 1–24 of bovine recombinant b‐FGF. Basic FGF immunoreactivity was evident from day 20 after birth in the endothelial cells and perivascular spaces of the gland. Although b‐FGF immunostaining showed its maximal expression at 30–45 days, it was maintained throughout the entire study period (up to 6 months), mainly in the distal zone of the gland. Pinealocytes did not show b‐FGF immunoreactivity at any time. There were no differences in the localization patterns or the intensity of b‐FGF immunostaining after the prenatal denervation with DSP‐4, a neurotoxic amine. The physiological role of b‐FGF in the adult pineal gland remains unknown; however, it does not seem to play a major role during the cytodifferentiation period of the parenchymal cells, or during the neovascularization in the early postnatal days. Furthermore, its immunocytochemical expression is not affected by the prenatal sympathetic denervation with DSP‐4, in contrast with other neutrophic factors.
Multiple circadian oscillators in the photosensitive pike pineal gland: A study using organ and cell culture
Authors: Bolliet Valérie , Bégay Valérie , Ravault Jean‐Paul , Ali Mohamed A. , Collin Jean‐Pierre , Falcón Jack 
Published: February 2007

Bolliet V, Bégay V, Ravault J‐P, Ali MA, Collin J‐P, Falcón J. Multiple circadian oscillators in the photosensitive pike pineal gland: A study using organ and cell culture. J. Pineal Res. 1994: 16: 77–84.AbstractThe fish pineal organ contains typical and, in some species, modified photoreceptor cells involved in the photoperiodic control of melatonin production. In the majority of species studied, the rhythm in melatonin production is driven by an intra‐pineal circadian oscillator synchronized by the light: dark cycle. In the present study, it is shown that the endogenous rhythm in melatonin release of super fused pike pineals maintained under constant darkness is expressed at temperatures of 19°C, 20°C, 25°C, and 30°C (period > 24 hr), but not at temperatures of 10°C and 15°C. Under constant darkness, pineal fractions containing either typical photoreceptors, modified photoreceptors, or both behaved like total organs. Dissociated pike pineal cells, cultured statically at 20°C, expressed a high amplitude rhythm in melatonin secretion under a light: dark cycle. Under constant darkness, circadian oscillations, which appeared better sustained than in organ culture, were also observed. This study provides the first evidence that the rhythmic production of melatonin, by a fish pineal, is driven by a population of circadian oscillators or clocks. It is hypothesized that each typical and modified photoreceptor might be the locus of a circadian clock. Damping of the overall rhythm under constant darkness might reflect the resynchronization (uncoupling) between these clocks and/or damping of individual oscillators.
Effect of pinealectomy upon the nonspecific immune response of the ring‐dove (Streptopelia risoria)
Authors: Rodriguez Ana B. , Lea Robert W. 
Published: February 2007

Rodriguez AB, Lea RW. Effect of pinealectomy upon the nonspecific immune response of the ring‐dove (Streptopelia risoria). J. Pineal Res. 1994; 16: 159–166.AbstractThe different stages of the phagocytic process by granulocytes of pinealectomized or sham‐pinealectomized ring doves (Streptopelia risoria) as well as hematological parameters (total white blood cells, smear, and total protein) and serum hormone levels (triiodothyronine (T3), thyroxine (T4), and corticosterone) were studied. A number of immunological parameters of the phagocytosis process, including adherence capacity, mobility rate, the phagocytosis capacity for inert particles and the digestion capacity of ingested material, were studied. Adult male ring doves were injected intravenously with either 0. 1 ml of normal sheep serum (NSS) or saline (SS). Blood samples were collected before injection, and 1 hr, 3 hr, 24 hr, and 4 days afterwards. The results indicate that pinealectomy produces a significant increase in the number of total white blood cells and total protein concentration in plasma in addition to altering different stages of the phagocytic process. During the immunization study, a decrease in the percentage of leukocytes and lymphocytes and an increase in the percentage of heterophils accompanied by an increase in the concentration of serum corticosterone were observed 3 hr following treatment. For the immunological parameters, adherence capacity and latex bead ingestion were increased 3 hr after NSS injection and the NBT reduction test 3 and 24 hr after NSS treatment. In addition, the administration of NSS produced a significant increase in serum T3 and T4 concentrations 4 days following injection. These results show that pinealectomy has a marked effect on both the number and function of immune cells.
Photoperiod and the pineal gland regulate the male phenotype of the Harderian glands of male Syrian hamsters after androgen withdrawal
Authors: Coto‐Montes Ana M. , Rodríguez‐Colunga Maria J. , Uria Higinio , Antolin Isaac , Tolivia Delio , Buzzell Gerald R. , Menendez‐Pelaez Armando 
Published: February 2007

Coto‐Montes AM, Rodriguez‐Colunga MJ, Una H, Antolin I, Tolivia D, Buzzell GR, Menendez‐Pelaez A. Photoperiod and the pineal gland regulate the male phenotype of the Haderian glands of male Syrian hamsters after androgen withdrawal. J. Pineal Res. 1994: 17: 48–54.AbstractThe Harderian glands of Syrian hamsters exhibit a marked sexual dimorphism in cell types and porphyrin production. The glands of male hamsters have two secretory cell types (Type I and II) while the glands of females consist of a single secretory cell type (female Type I) and large intraluminal deposits of porphyrins. Besides androgens, there is evidence that the pineal gland, through the secretion of melatonin, contributes to the maintenance of the “male” and “female” phenotypes. In this study, we investigated the effects of castration, short photoperiods, and pinealectomy on the distribution of secretory cells and porphyrin deposits in the Harderian glands of male Syrian hamsters. Two groups of animals were maintained in long days (14 hr light/day). Hamsters in one group were left intact and those in the other were castrated. Another three groups were maintained in short days (8 hr light/day); these animals were either left intact, castrated, or both castrated and pinealectomized. The duration of the experiment was 5 weeks. Castration of long photoperiod‐exposed animals resulted in a significant drop in the number of Type II cells and a large increase in the porphyrin deposits (P < 0. 01). However, castrated animals exposed to short photoperiod showed a significant smaller change in both parameters compared with those exposed to long days (P < 0. 05). Pinealectomy prevented the effects of short days in castrated animals. No significant changes were observed in the relative number of mitotic figures or in the number of cell nuclei, indicating that the changes observed were due in part to a transformation of Type II into Type I cells. In a second experiment, male hamsters were injected daily either with 25 μg of melatonin late in the afternoon or with the saline for 8 weeks. The administration of melatonin resulted in a significant (P < 0. 05) increase in the percentage of Type II cells. We conclude that when circulating androgens are very low or absent, pineal melatonin maintains the male phenotype in the Syrian hamster Harderian gland.
Effects of melatonin on microtubule assembly depend on hormone concentration: Role of melatonin as a calmodulin antagonist
Authors: Huerto‐Delgadillo Lourdes , Antón‐Tay Fernando , Benitez‐King Gloria 
Published: February 2007

Huerto‐Delgadillo L, Antón‐Tay F, Benítez‐King G. Effects of melatonin on microtubule assembly depend on hormone concentration: rate of melatonin as a calmodulin antagonist. J. Pineal Res. 1994: 17: 55–62. ©Munksgaard, 1994AbstractMelatonin may play a key role in cytoskeletal rearrangements through its calmodulin antagonism. In the present work, we tested this hypothesis by studying melatonin effects on both microtubule polymerization in vitro and cytoskeletons in situ. Microtubule assembly is a dynamic process inhibited by Ca2+/calmodulin. Calmodulin antagonists prevent the inhibition by binding to Ca2+‐activated calmodulin, thus causing microtubule enlargement. In the presence of calmodulin (5 μM) and CaCl2 (1 mM), polymerization at equilibrium was inhibited by 40%. Complete reversal of the Ca2+/calmodulin effect on microtubules was observed with 10‐9 M melatonin or with 10‐5 M trifluoperazine or 1 μg/ml of compound 48/80. In the absence of Ca2+/calmodulin, melatonin at 10‐5 M inhibited tubulin polymerization like 10‐4 M trifluoperazine does. Melatonin effects on microtubule assembly at both nanomolar and micromolar ranges were corroborated in cytoskeletons in situ. Therefore, it is suggested that at a low concentration (10‐9 M), cytoskeletal melatonin effects are mediated by its antagonism to Ca2+/calmodulin. At a higher concentration (10‐5 M), non‐specific binding of melatonin to tubulin occurs, thus overcoming the melatonin antgonism to Ca2+/calmodulin. The results support the hypothesis that under physiological conditions, melatonin synchronizes different body rhythms through cytoskeletal rearrangements mediated by its calmodulin antagonism.
Clonidine in vivo mimics the acute suppressive but not the phase‐shifting effects of light on circadian rhythm of serotonin N‐acetyltransferase activity in chick pineal gland
Authors: Zawilska Jolanta B. 
Published: February 2007

Zawilska JB. Clonidine in vivo mimics the acute suppressive but not the phase‐shifting effects of light on circadian rhythm of serotonin N‐acetyltransferase activity in chick pineal gland. J. Pineal Res. 1994; 17: 63–68. ©Munksgaard, 1994AbstractComparative in vivo studies on effects of pulses of light and clonidine, a selective agonist of α2‐adrenergic receptors, on the circadian rhythm of serotonin N‐acetyltransferase (NAT) activity in chick pineal gland were performed. Six‐hour pulses of white light caused an acute suppression of the nocturnal NAT activity and phase‐dependent phase shifts of the circadian rhythm of the enzyme activity relative to controls. Systemic administration of clonidine acutely suppressed NAT activity of chick pineal gland, but did not affect the phase of subsequent cycles in constant darkness. These results give further support to the concept based on in vitro studies that α2‐adrenergic receptors are involved in regulation of melatonin biosynthesis in chick pineal gland by a mechanism distal to the pacemaker that generates the circadian melatonin rhythm.
Benzodiazepines influence melatonin secretion of the pineal organ of the trout in vitro
Authors: Meissl Hilmar , Yáñez Julián , Ekström Peter , Grossmann Eberhard 
Published: February 2007

Meissl H, Yáñez J, Ekström P, Grossman E. Benzodiazepines influence melatonin secretion of the pineal organ of the trout in vitro. J. Pineal Res. 1994; 17: 69–78. ©Munksgaard, 1994AbstractThe effect of benzodiazepines (BZP) on melatonin release was investigated in the pineal gland of the rainbow trout, Oncorhynchus mykiss, maintained under in vitro perifusion culture conditions. Melatonin and the methoxyindoles 5‐methoxytryptophol (5‐MTOL), 5‐methoxyindoleacetic acid (5‐MIAA), and 5‐methoxytryptamine (5‐MT) were determined directly in samples of the supervision medium by HPLC with electrochemical detection. Melatonin release was significantly increased by addition of diazepam and clonazepam in a dose‐related and reversible manner. The effects of benzodiazepines were more pronounced in light‐adapted pineal organs, when melatonin secretion is low, than under scotopic conditions. When the perifusion medium was replaced by a medium containing low calcium, high magnesium concentrations, melatonin release was considerably decreased by 70% in light‐adapted and 20% in dark‐adapted pineal organs. Addition of diazepam to low Ca2+, high Mg2+‐medium reversed the decrease of melatonin release and produced a clear rise in its secretion rate. Addition of the BZP antagonist flumazenil to the perifusion medium slightly decreased melatonin release in the light‐ and dark‐adapted state, whereas the peripheral receptor antagonist PK 11195 did not alter melatonin release. The effect of diazepam is reduced by simultaneous addition of flumazenil to the superfusion medium, suggesting that the effects of diazepam are receptor‐mediated. The methoxyindoles 5‐MTOL, 5‐MIAA, and 5‐MT showed no significant changes of their release pattern after diazepam application in light‐ and dark‐adapted pineal organs. These results suggest that BZP can influence melatonin production and release by an intrapineal action possibly on the melatonin synthesizing photoreceptor cell.
Calbindin‐D28k, calretinin, and recovering immunoreactivities in developing chick pineal gland
Authors: Bastianelli E. , Pochet R. 
Published: February 2007

Bastianelli E, Pochet R. Calbindin‐D28k, calretinin, and recover in immunoreactivities in developing chick pineal gland. J. Pineal Res. 1994: 17: 103–111.AbstractCalbindin‐D28k, calretinin, and recoverin, three intracellular calcium‐binding proteins belonging to the troponin C/calmodulin superfamily, were immunohistochemically localized in chick pineal during development [from embryonic day 16 (E16) to postnatal day 14 (P14)]. At E18, only calretinin immunoreactivity could be detected in nuclei from follicular pinealocytes. With development, calretinin immunoreactivity expanded from nucleus to cytoplasm, and calretinin immuno‐positive cell number increased. At P14 almost all pinealocytes were calretinin positive. Calbindin‐D28k immunoreactivity was not detected before E20. During development, many follicular and parafollicular pinealocytes became strongly calbindin‐D28k positive, reaching a peak both in intensity and in number at P7; thereafter their number decreased. In addition to pinealocytes, neuron‐like cells appeared calbindin‐D28k positive at E20 and calretinin positive at P7. Recoverin, a myristoylated protein isolated from vertebrate photoreceptor and which might participate in the inactivation of the phototransduction cascade, was transiently expressed in follicular and parafollicular pinealocytes from P1 to P14 with a maximal expression at P7. This transitory expression may coincide with a transitory light sensitivity period in chick pinealocytes, before complete maturity of the pineal gland.
Response of collared lemmings to melatonin: I. Implants and photoperiod
Authors: Nagy Tim R. , Gower Barbara A. , Stetson Milton H. 
Published: February 2007

Nagy TR, Gower BA, Stetson MH. Response of collared lemmings to melatonin: I. Implants and photoperiod. J. Pineal Res. 1994:17:177–184.AbstractWe examined the effect of constant‐release melatonin capsules on the physiology and morphology of female collared lemmings exposed to either chronic long (22L:2D) or short (8L:16D) photoperiod, or to a change in photoperiod. When animals were maintained on unchanging long or short photoperiod, subcutaneous melatonin implants were without effect. However, when animals were reared on either 22L:2D or 8L:16D and transferred to the alternate photoperiod at weaning, melatonin (implanted at weaning) prevented most photoperiod‐related responses. At sacrifice (after 8 weeks of treatment), melatonin‐implanted animals exposed to a change in photoperiod did not differ from animals remaining in the original photoperiod with respect to pelage color, bifid claw size, uterine mass, or serum prolactin (PRL). In contrast, regardless of treatment, animals exposed to a photoperiod transfer developed a body mass that partially or fully reflected that characteristic of the secondary photoperiod; i. e., both control‐ and melatonin‐implanted animals transferred from long to short photoperiod developed a large body mass. These results indicate that masking the endogenous melatonin rhythm via constant‐release melatonin implants renders collared lemmings unable to respond to a change in photoperiod with respect to most physiological parameters. However, the striking seasonal change in body mass experienced by collared lemmings appears to be at least partially independent of a melatonin signal.