Disease relevance of Pineal Gland

• Breast cancer is frequently a hormone-dependent tumour, and several studies have suggested that the pineal gland hormone melatonin may influence the growth and development of this malignancy [1].
• It can be spec-lated that since labelled MRIP-I accumualtes in the pineal and melatonin blunts GH response to hypoglycemia, the pineal gland might be involved in the MRIP-I-induced suppression of GH secretion [2].
• The rates of melatonin formation and its diurnal fluctuations have been examined in patients with three types of orthostatic hypotension by measuring the urinary excretion rates of 6-hydroxymelatonin, the major metabolite of the pineal gland hormone [3].
• Melatonin, the main secretory product of the pineal gland, has been shown to be potentially effective in prevention of numerous types of neurodegenerative disorders in which free radical processes are involved [4].
• No differences in GFAP or vimentin immunoreactivity were noted in pineal glands from horses with or without uveitis [5].

Psychiatry related information on Pineal Gland

• In this study, pineal gland function was examined by measuring nocturnal serum melatonin levels during both wakefulness and sleep in depressed children and adolescents [6].
• Vasotocin, melatonin and narcolepsy: possible involvement of the pineal gland in its patho-physiological mechanism [7].
• The authors prepared SCN, pineal gland, pituitary, and cornea cultures from transgenic Period1-luciferaserats whose body temperature and locomotor activity were arrhythmic and from several groups of rhythmic rats held in LD, DD, and short-term LL [8].
• The pineal gland and particularly its major hormone, melatonin, may participate in several physiological functions, including sleep promotion, anticonvulsant activity and the modulation of biological rhythms and affective disorders [9].
• OBJECTIVES: Recent studies have suggested the involvement of the pineal gland and its main hormone melatonin (MLT) in the pathogenesis of psychiatric disturbances, namely the depressive syndrome [10].

High impact information on Pineal Gland

• Crx has been proposed to have a role in the regulation of photoreceptor-specific genes in the eye and of pineal-specific genes in the pineal gland [11].
• Crx, an Otx-like homeobox gene, is expressed specifically in the photoreceptors of the retina and the pinealocytes of the pineal gland [11].
• Horizontal displacement of the pineal body of 0 to 3 mm from the midline was associated with alertness, 3 to 4 mm with drowsiness, 6 to 8.5 mm with stupor, and 8 to 13 mm with coma [12].
• Disappearance of plasma melatonin after removal of a neoplastic pineal gland [13].
• Diurnal variation in mRNA encoding serotonin N-acetyltransferase in pineal gland [14].

Chemical compound and disease context of Pineal Gland

• These data demonstrate that ganglion cell activity in the trout pineal gland is under the influence of several neurotransmitters, including acetylcholine, dopamine, norepinephrine, and GABA, which is in contrast to the originally proposed simple bineuronal transduction pathway from photoreceptors onto ganglion cells [15].
• Potential antidepressant activity in this subset was assayed in three rodent models--the antagonism of reserpine-induced hypothermia, the antagonism of histamine-induced ACTH release, and the ability to reduce noradrenergic responsiveness in the rat pineal gland [16].
• On the other hand, taurine content in each cerebellar region and pineal body decreased with the administration of 30 mg of DL-propargylglycine per 200 g body weight [17].
• Crude ethanol extracts of rat pineal glands were tested for tumor-inhibiting activity in an in vitro microbioassay using human erythroleukemia cells which could not be inhibited by melatonin [18].
• Previous studies showed that melatonin, the principle secretory product of the pineal gland, binds Cupric chloride (Cu2+) and that this may have implications in copper-induced neurodegenerative diseases [19].

Biological context of Pineal Gland

• Cells of the chick pineal gland have a photosensitive circadian rhythm in melatonin secretion that persists in dissociated cell culture [20].
• N-Acetyltransferase activity in rat pineal gland is controlled by the central nervous system through the sympathetic nerves from the superior cervical ganglion, while in chicken the endogenous oscillator for N-acetyltransferase rhythm is presumably located in the pineal gland [21].
• Otx2 homeobox gene controls retinal photoreceptor cell fate and pineal gland development [22].
• The activity of soluble protein kinase (ATP:protein phosphotransferase,EC 2.7.1.37) and pattern of nuclear protein phosphorylation was monitored in cultured rat pineal glands during the induction of serotonin N-acetyltransferase (acetyl-CoA:serotonin N-acetyltransferase;EC 2.3.1.5)by l-isoproterenol [23].
• The product of one of these genes has extensive sequence homology to phosducin, a phosphoprotein expressed in retina and pineal gland that modulates trimeric guanine nucleotide-binding protein (G protein) function by binding to G-protein beta gamma subunits [24].

Anatomical context of Pineal Gland

• In mammals the pineal gland is responsible for the synthesis of the hormone melatonin in response to signals originating from the endogenous clock located in the hypothalamic suprachiasmatic nucleus (SCN) [25].
• Electrical stimulation of the superior cervical ganglia causes a rapid increase in the concentration of cyclic AMP in the pineal gland of rats [26].
• Studies of the adrenergic regulation of cyclic GMP in the pineal gland show that (-)-norepinephrine stimulates cyclic GMP primarily in pineal cells, rather than in nerve endings as previously thought [27].
• Computer-generated maps revealed binding in brain regions not identified previously with 125I-muNGF, including hippocampus; dentate gyrus; amygdala; paraventricular thalamus; frontal, parietal, occipital, and cingulate cortices; nucleus accumbens; olfactory tubercle; subiculum; pineal gland; and medial geniculate nucleus [28].
• F4/80+ cells line vascular sinuses and capillaries in anterior and posterior pituitary, adrenal cortex, corpus luteum, parathyroid, pineal gland, and islets of Langerhans [29].

Associations of Pineal Gland with chemical compounds

• Diurnal cycles in serotonin acetyltransferase activity and cyclic GMP content of cultured chick pineal glands [30].
• Noradrenaline, released from sympathetic nerve terminals in the pineal gland, regulates a large nocturnal increase in melatonin synthesis by stimulating the activity of arylalkylamine N-acetyltransferase (NAT, EC 2.3.1.87) 30-70-fold [31].
• A cyclic GMP-activated channel in dissociated cells of the chick pineal gland [20].
• Immunocytochemical evidence for the presence of arginine vasotocin in the rat pineal gland [32].
• Biosynthesis of biopterin: adrenergic cyclic adenosine monophosphate-dependent inhibition in the pineal gland [33].

Gene context of Pineal Gland

• The abundance of AA-NAT messenger RNA (mRNA) during the day was high in the ovine pineal gland and somewhat lower in retina [34].
• Otx2-deficiency converted differentiating photoreceptor cells to amacrine-like neurons and led to a total lack of pinealocytes in the pineal gland [22].
• Polymicrogyria and absence of pineal gland due to PAX6 mutation [35].
• An en passant observation concerned high levels of NR2C mRNA in the pineal gland [36].
• BDNF is present in the pineal gland during target innervation, and incoming sympathetic axons are p75NTR positive [37].

Analytical, diagnostic and therapeutic context of Pineal Gland

• Recently it has been shown that N-acetyltransferase activity oscillates in a circadian manner in the organ culture of chicken pineal glands [21].
• From in vivo studies on animal models of tumorigenesis, the general conclusion is that experimental manipulations activating the pineal gland, or the administration of melatonin, enlarge the latency and reduce the incidence and growth rate of chemically induced mammary tumors, while pinealectomy usually has the opposite effects [38].
• We have established a system that enables long-term monitoring of melatonin secretion by implanting a transverse microdialysis probe in or near the pineal gland in a freely moving mouse [39].
• Electrical stimulation of sympathetic nerves increases the concentration of cyclic AMP in rat pineal gland [26].
• The time course of the recovery of nocturnal NAT activity after unilateral denervation of the pineal gland was similar to the time course of the decrease in norepinephrine uptake sites in the gland.(ABSTRACT TRUNCATED AT 250 WORDS)[40]

References