The chick pineal gland and retina synthesize melatonin in a circadian rhythm with high levels during the night. The rhythmic changes in the hormone production result predominantly from the fluctuation in the activity of serotonin N-acetyltransferase (AA-NAT), a penultimate and key regulatory enzyme in melatonin biosynthesis. The aim of this study was to analyze the effects of an acute and prolo...

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 observed for the first time, both in the pineal gland and in extrapineal nodules. Throughout the second week, the pineal parenchyma shows a cordonal pa...

BACKGROUND The majority of patients with schizophrenia and mood disorders have disruptions in sleep and circadian rhythm. Melatonin, which is secreted by the human pineal gland, plays an important role in sleep and circadian rhythm. The aim of the present study was to evaluate and compare pineal gland volumes in patients with schizophrenia and mood disorders. SUBJECTS AND METHODS We retrospec...

Pineal gland is a very important neuroendocrine organ with many physiological functions such as regulating circadian rhythm. Radiologically, the pineal gland volume is clinically important because it is usually difficult to distinguish small pineal tumors via magnetic resonance imaging (MRI). Although many studies have estimated the pineal gland volume using different techniques, to the best of...

The rhythmic melatonin synthesis in the pineal gland is one of the most extensively studied circadian rhythms in vertebrates. Light is the dominant environmental factor controlling this process. Light at night acutely suppresses pineal melatonin content and activity of serotonin N-acetyltransferase (AANAT; the key and penultimate enzyme in the hormone biosynthetic pathway). In addition, pulses ...

Exposure to light reduces the ability of the rat pineal gland to synthesize melatonin and decreases the weight of the gland. When the sympathetic nerves to the pineal gland are cut, light no longer has an effect on melatonin synthesis or pineal weight. The response of the gland does not require that the gonads or the pituitary gland be present.

The pineal hormone melatonin is involved in physiological transduction of temporal information from the light dark cycle to circadian and seasonal behavioural rhythms, as well as possessing neuroprotective properties. Melatonin and its receptors MT1 and MT2, which belong to the family of G protein-coupled receptors, are impaired in Alzheimer's disease (AD) with severe consequences to neuropatho...

A study was carried out to determine possible effects of 60-Hz electromagnetic-field exposure on pineal gland function in humans. Overnight excretion of urinary 6-hydroxymelatonin sulfate (6-OHMS), a stable urinary metabolite of the pineal hormone melatonin, was used to assess pineal gland function in 42 volunteers who used standard (conventional) or modified continuous polymer wire (CPW) elect...

The pineal gland is known to play a central role in the photoperiodic control of reproduction in seasonal breeders. The present review, based on experimental data obtained in four different species of hamster, the Syrian or golden, the Djungarian or Siberian, the Turkish and the European, attempts to evaluate the role of the pineal in this phenomenon, the message which is conveyed from this gla...

PURPOSE The purpose of this study was to evaluate the morphologic magnetic resonance imaging (MRI) characteristics of the pineal gland in retinoblastoma (Rb) patients without and with pineoblastoma in comparison to age-matched controls to improve early identification of pineoblastomas (trilateral retinoblastoma, TRb). METHODS AND MATERIALS 80 patients with retinoblastoma and 80 age-matched co...