Light sensitivity of the pineal has been retained in most vertebrates, except mammals. Retinal photoreceptors and pinealocytes share common components of light-dependent signaling pathways. In particular, an ion channel gated by cGMP has been electrophysiologically identified in chick pinealocytes; however, the physiological function of a light-sensitive enzyme cascade is not known, and primary...

In the developing central nervous system, the cell cycle clock plays a crucial role in determining cell fate specification. A second clock, the circadian oscillator, generates daily rhythms of cell cycle progression. Although these two clocks interact, the mechanisms linking circadian cell cycle progression and cell fate determination are still poorly understood. A convenient system to address ...

The isolation of melatonin was first reported in 1958. Since the demonstration that pineal melatonin synthesis reflects both daily and seasonal time, melatonin has become a key element of chronobiology research. In mammals, pineal melatonin is essential for transducing day-length information into seasonal physiological responses. Due to its lipophilic nature, melatonin is able to cross the plac...

Arginine-vasopressin and oxytocin in various portions of rat brain were determined by radioimmunoassays. The hormones were extracted from tissue samples into 0.1 N HCl and then purified partially with acetone-petroleum ether extraction. The non-equilibration method was used for the assays. In this method recovery rates of arginine-vasopressin and oxytocin were 73.0 +/- 4.4% and 75.0 +/- 3.8%, r...

We describe here an autoradiographic method to measure the in vivo rate of serotonin synthesis in rat brain. The method is based on the use of the L-tryptophan analogue alpha-methyl-L-tryptophan (alpha-MTrp), which is converted in vivo into alpha-methylserotonin (alpha-M5HT). Since alpha-M5HT is not a substrate for monoamine oxidase, it is accumulated in the brain tissue. Data are presented to ...

The master circadian clock in fish has been considered to reside in the pineal gland. This dogma is challenged, however, by the finding that most zebrafish tissues contain molecular clocks that are directly reset by light. To further examine the role of the pineal gland oscillator in the zebrafish circadian system, we generated a transgenic line in which the molecular clock is selectively block...

Neural signals transmitted from the pineal organ to the brain in cold-blooded vertebrates provide information about ambient illumination, information of importance for the synchronization of activity rhythms with the light-dark cycle. The ultrastructure of intrapineal projection neurons (pineal "ganglion cells") was studied after retrograde filling with HRP through their cut axons. The dominati...

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 1-, 7-, 14- and 28-day-old rats. Numerical density, tak...

A 21-year-old male presented with a pineal dermoid cyst manifesting as headache and diplopia. He had undergone gross total removal of a pineal mature teratoma 18 years before and had done well until recently. Diffusion-weighted magnetic resonance imaging showed a region of high signal intensity due to a round mass in the pineal region and extending into the trigone of the right lateral ventricl...

Melatonin receptor gene expression as well as melatonin synthesis and secretion activities were examined in the pineal gland of the grass puffer, which exhibits unique lunar/tidal cycle-synchronized mass spawing: spawning occurs before high tide on the day of spring tide during spawing season. Melatonin synthesizing activity was assessed by the abundance of arylalkylamine N-acetyltransferase 2 ...