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An essential role for ovarian inhibin in pineal gland-mediated anestrus in Syrian hamsters.

When transferred from long photoperiod (LP) to short photoperiod (SP), female Syrian hamsters exhibit depressions of follicle stimulating hormone (FSH) and follicular development, cessation of ovulation, and marked ovarian interstitial tissue hyperplasia. Pinealectomy prevents these effects of SP. The object of this study was to determine the role of inhibin in the regulation of FSH during SP-induced anestrus. Adult LSH/SsLak hamsters maintained in LP (LD 14:10 hr) were transferred to SP (LD 8:16 hr) on the day of estrus, and groups of animals killed at either 16.00 hr on proestrus or 08.00 hr…

Evidence for melatonin synthesis in rodent Harderian gland: a dynamic in vitro study.

Melatonin content and release from Harderian glands (HGs) has been measured by an in vitro perifusion technique in three rodent species: Wis … TRP-induced melatonin stimulation. Kinetics and amounts of melatonin released were not affected by pinealectomy, ruling out a possible plasmatic origin of the HG melatonin. Isoproterenol, a beta-adrenergic agonist, and dibutyryl cyclic AMP, a cyclic AMP analogue, failed to stimulate HG melatonin secretion. In conclusion, these results confirm the presence of …

Androgenic control of porphyrin in the Harderian glands of the male Syrian hamster is modulated by the photoperiod, which suggests that the sexual differences in porphyrin concentrations in this gland are important functionally.

BACKGROUND: The porphyrin concentrations of the Harderian glands of Syrian hamsters show marked sexual differences, with male levels being m … osure (13 weeks) led to increased Harderian porphyrin concentrations and this rise was prevented by pinealectomy. The rise in Harderian porphyrins following short-day exposure was small, compared with that following castration. Short-day photoperiods also prevented the rise in porphyrin levels associated with castration and this effect was prevented by removal …

Comparative aspects of the pineal/melatonin system of poikilothermic vertebrates.

The pineal gland of poikilothermic vertebrates originates as an evagination from the diencephalic roof between the habenular and the posteri … ponsible for many biological rhythms exhibited by lower vertebrates. These rhythms are abolished by pinealectomy in some species, but not in others, suggesting the existence of an extra-pineal pacemaker. The photoperiod and the temperature (especially in reptiles) are the main environmental factors affecting the secretory rhythm of melatonin. Poikilothermic ve …

Bipedal ambulation induces experimental scoliosis in C57BL/6J mice with reduced plasma and pineal melatonin levels.

In addition to the induction of scoliosis in chickens by pinealectomy (PINX), we previously demonstrated that removal of the pineal gland also produces scoliosis in bipedal rats, which can be inhibited by melatonin treatment. Using C57BL/6J mice with genetically low circulating melatonin levels, the main objective of the present study was to investigate whether bipedal ambulation in C57BL/6J mice has the same effects on spinal deformity as those seen in pinealectomized bipedal rats. The present study consisted of two phases. The aim of the first experiment was to determine whether the C57BL/6J…

Central gabaergic mechanisms as targets for melatonin activity in brain.

The pineal gland serves the function of a neuroendocrine transducer converting information about day length into the nocturnal release of me … ic acid (GABA) as an inhibitory transmitter are a target for pineal melatonin activity because: (a) pinealectomy (Px) disrupts circadian rhythmicity of brain GABA and benzodiazepine (BZP) binding; (b) low doses of melatonin counteract Px-induced modifications of BZP and GABA binding; (c) chronic melatonin treatment increases brain BZP and GABA binding; (d) mel …

Annual reproductive rhythms in mammals: mechanisms of light synchronization.

Animals restrict the time of birth of offspring to the most advantageous time of year, usually spring or summer. This is achieved by control … oorly understood. The pineal is an essential mediator of the photoperiodic response. The effects of pinealectomy vary between species, but in all cases the responses to changes in day length are blocked. The gland is neither anti- nor progonadotrophic; it merely provides a signal. This signal is probably the nocturnal release of melatonin. Studies on in vivo m …

Modulation of immunity in young-adult and aged squirrel, Funambulus pennanti by melatonin and p-chlorophenylalanine.

BACKGROUND: Our interest was to find out whether pineal gland and their by melatonin act as modulator of immunosenescence. Parachlorophenylalanine (PCPA) - a beta adrenergic blocker, is known to perform chemical pinealectomy (Px) by suppressing indirectly the substrate 5-hydroxytryptamine (5-HT) for melatonin synthesis and thereby melatonin itself. The role of PCPA, alone and in combination with melatonin was recorded in immunomodulation and free radical load in spleen of young adult and aged seasonal breeder Indian palm squirrel Funambulus pennanti. RESULTS: Aged squirrel presented reduced i…

Physiological pineal effects on female reproductive function of laboratory rats: prenatal development of pups, litter size and estrous cycle in middle age.

The present study investigates whether and how the pineal or its hormone melatonin influences female reproductive functions, namely the litt … mental processes, especially pregnancy and the timing of reproductive aging in rats. The effects of pinealectomy are more prominent at an age of 60 to 80 days (i.e., shortly after puberty) and at the beginning of the cessation of cycles in middle-aged females.

The megachiropteran pineal organ: a comparative morphological and volumetric investigation with special emphasis on the remarkably large pineal of Dobsonia praedatrix.

This investigation is based upon the pineal organs of 92 specimens of 36 species of the family Pteropodidae (Mammalia, Chiroptera). The size of the megachiropteran pineal correlates well with body size (r = 0.864), confirming the former conclusions that generally larger bodied bats have larger pineals. The range of the pineal size index in 36 megachiropteran species is from 33 to 4393. In most species the pineal organs are small, deeply recessed under the cerebral hemispheres and of Type A (except in Dobsonia and Pteropus, where they are of Type alpha beta C and AB, respectively). Morphologica

Duration of melatonin regulates seasonal plasticity in subtropical Indian weaver bird, Ploceus philippinus.

Day length regulates seasonal plasticity connected with reproduction in birds. Rhythmic pineal melatonin secretion is a reliable indicator of the night length, hence day length. Removal of rhythmic melatonin secretion by exposure to constant bright light (LLbright) or by pinealectomy renders several species of songbirds including Indian weaver bird (Ploceus philippinus) arrhythmic. Present study investigated whether rhythmic melatonin is involved in the regulation of key reproductive neuropeptides (GnRH I and GnIH) and reproduction linked neural changes, viz. song control nuclei, in Indian wea…

Transcutaneous auricular vagal nerve stimulation modulates blood glucose in ZDF rats via intestinal melatonin receptors and melatonin secretion.

BACKGROUND: Melatonin (MLT) and its receptor deficiency have been shown to be associated with type 2 diabetes mellitus (T2DM). Transcutaneou … re used. Forty ZDF rats were randomized into ZDF, taVNS, Px + taVNS and Lu + Px + taVNS groups (Px: pinealectomy, Lu: Luzindole). ZL rats served as a control group for comparison with ZDF rats without involvement in the taVNS intervention. Thirty min-taVNS interventions (2/15 Hz, 2 mA, 30 min/days) were administered once daily under anesthesia for 3 consecutiv …

Study on pineal function and DMBA-induced breast cancer formation in rats during exposure to a 100-mG, 50 Hz magnetic field.

Reduction of circulating melatonin levels by pinealectomy or constant light has previously been shown to enhance the development and growth of mammary cancers induced by the polyaromatic hydrocarbon 7,12-dimethylbenz[a]anthracene (DMBA) in female rats. Since pineal melatonin production can also be disturbed by electromagnetic field exposure, we studied whether there is an association between melatonin depression by magnetic field (MF) exposure and DMBA-induced breast cancer growth in female rats. In the present experiments, 216 female Sprague-Dawley rats were divided into 4 groups. Two of the …

[Thyroid reactions in Wistar rats during the circadian rhythm after ganglionectomy at normal temperature and under cold exposure with regard to the influence of the epiphysis cerebri].

Serum thyroxin (T4), serum TSH, and pituitary TSH were measured by radioimmunoassay (RIA) and serum cholesterol by Liebermann-Burchard react … similar results in another long-time experiment (90 d exposure) after gangliectomy as well as after pinealectomy. There also appears a lowered thyroxin and an increased cholesterol level (in dependency on the seasons). Gangliectomy induced a decrease of the pineal weight and a compensatory thyroid growth. Exposure to cold induced an increase of pituitary and p …

Pineal oscillator functioning in the chicken--effect of photoperiod and melatonin.

The avian pineal gland, apart from the hypothalamic master clock (suprachiasmatic nuclei, SCN) and retina, functions as an independent circa … pothesized that rearing chickens from the day of hatch under LL conditions would evoke a functional pinealectomy, influencing, in turn, pineal clock function. To verify this hypothesis, we examined the diurnal transcriptional profiles of selected clock genes as well as the essential parameters of pineal gland function: transcription of the genes encoding aryla …

Melatonin and mammary cancer: a short review.

Melatonin is an indolic hormone produced mainly by the pineal gland. The former hypothesis of its possible role in mammary cancer developmen … melatonin lengthens the latency and reduces the incidence and growth rate of mammary tumors, while pinealectomy usually has the opposite effects. Melatonin also reduces the incidence of spontaneous mammary tumors in different kinds of transgenic mice (c-neu and N-ras) and mice from strains with a high tumoral incidence. In vitro experiments, carried out with …

Pineal factors in the control of testicular function.

The mammalian pineal gland has become firmly established as a neuroendocrine structure possessing the ability to influence the functions of … levels of FSH and LH. Prolactin also has been shown to respond to change in ambient lighting and to pinealectomy. Partially purified polypeptide fractions are now claimed to be considerably more potent antigonadotropically than melatonin, the indole most favored as a pineal hormone...

Chronic disruptions of circadian sleep regulation induce specific proinflammatory responses in the rat colon.

UNLABELLED: Exposure to environmental conditions that disturb the daily rhythms has been shown to enhance the proinflammatory responses of i … light/dark cycle; LL: constant light; LPS: lipopolysaccharide; Mntr1a: melatonin receptor 1a; PINX: pinealectomy; Rgs16: regulator of G protein signaling 16; RT qPCR: quantitative reverse transcription polymerase chain reaction; Stat3: signal transducer and activator of transcription 3; Th17: type 17 T helper cells; Tnfα: tumor necrosis factor α; Tnfrsf1b: tum …

Mechanisms of esophageal protection, gastroprotection and ulcer healing by melatonin. implications for the therapeutic use of melatonin in gastroesophageal reflux disease (GERD) and peptic ulcer disease.

Melatonin is a potent reactive oxygen metabolite scavenger and antioxidant that has been shown to influence many physiological functions of … which also was shown to exhibit protective and trophic effects in the upper GItract. Interestingly, pinealectomy, which suppressed plasma melatonin levels, markedly exacerbated gastric lesions induced by topical and non-topical ulcerogens and these effects are counteracted by a concurrent supplementation with melatonin. Evidence is provided that exogenous mela …

Эффективность неевроиммунной терапии, включая митоксиндолы, ангиотензин 1-7 и эндоканнабиноиды рака, аутоиммунной и нейродегенеративной болезни.

ЦЕЛЬ: Последние достижения в области психо-нейро-эндокринной-иммунологии свидетельствуют о том, что многочисленные неинфекционные заболевания (НИЗ) возникают в результате сбоев в функционировании иммунной сети цитокина, что приводит к хроническим подстрекательским реакциям. Эта устойчивая низколаминированная воспаление объясняется недостатками важнейших внутренних нейроноэндокринных систем против воспаления, включая синусовую железу, эндоканнабиноидную систему и ось ангиотенсина, предотвращающего фермент 2 / ангиотенсина 1-7. Управление сосновыми метоксиндолами (мелатонин, 5-метокситриптамин),

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… In addition to melatonin, the pineal produces other relevant antitumor indole hormones, like 5-methoxytryptamine, 49 and beta-carbolines. 50 , 51 This explains why the increase in tumour growth that follows pinealectomy cannot be totally counteracted by the exogenous administration of melatonin. 5- …