Electrical responses of homing pigeon and guinea pig Purkinje cells to pineal indoleamines applied by microelectrophoresis

The effects of microelectrophoretically applied melatonin (aMT), 5-methoxytryptophol (ML), 5-hydroxytryptophol (HL) and noradrenaline (NA) on the electrical activity of cerebellar Purkinje and other cells during both day- and nighttime were studied in urethane-anesthetized intact and pinealectomized homing pigeons and guinea pigs.

Magnetic Sensitive Pineal Cells in Pigeons

The electrical activity of about 30% of a homing pigeon’s pineal cells can be altered by changing the horizontal or vertical component of the natural magnetic field, using two pairs of Helmholtz coils. The cells respond to a rapid and/or gradual change in the magnetic field with either excitation or inhibition. In some of the sensitive cells the responses to magnetic field changes could not be repeated.

Effects of an artificial magnetic field on serotonin N-acetyltransferase activity and melatonin content of the rat pineal gland

In the present study the effects of artificial magnetic fields on pineal serotonin-N-acetyltransferase (NAT) activity and melatonin content in male Sprague-Dawley rats were investigated to study the secretory activity of the pineal gland. Experimental inversion of the horizontal component of the natural magnetic field, performed at night-time, led to a significant decrease of both parameters investigated. During day-time, this effect was less conspicuous. During night-time, inversion of the horizontal component is followed by a reduced pineal secretory activity for about 2 h. After 24 h exposure to the inverted horizontal component, return to the natural condition was followed by a renewed …

Electrophysiology of the Mammalian Pineal Gland: Evidence for Rhythmical and Non-Rhythmical Elements and for Magnetic Influence on Electrical Activity

Although the mammalian pineal gland has been extensively studied by biochemical, pharmacological and morphological techniques, the precise nature of the intrinsic cells, the pinealocytes, was unknown for a long time. Biochemically the pinealocyte has been shown to be an endocrine cell synthesizing melatonin and other hormones. In view of the importance of the mammalian pineal as a neurotransducer, and of the limited usefulness of the methods mentioned, an attempt was made to characterize the cells electro-physiologically.

Effects of an earth-strength magnetic field on pineal melatonin synthesis in pigeons

Electrical responses of pineal cells to melatonin and putative transmitters

The effects of microelectrophoretically applied melatonin (N-acetyl-5-methoxy-tryptamine), noradrenaline (NOR) or acetylcholine (ACH) on the electrical activity of pineal cells during both the day- and night-time were studied in urethane anesthetised guinea-pigs. A total of 288 cells were tested with melatonin, and in addition with either NOR (120 cells) or ACH (138 cells). Of the 206 cells responding to melatonin application, 139 were excited and 67 inhibited. A total of 85 cells responded to the application of NOR, 45 being excited and 40 inhibited. Responses to ACH application were observed in 75 pineal cells, 49 units being inhibited and 26 excited. It was possible to observe excitation…

The effects of sex hormones, prolactin, and chorionic gonadotropin on pineal electrical activity in guinea pigs.

Microelectrophoretic application of sex hormones onto pineal cells in guinea pigs has shown different responses in pregnant females as compared to males. In pregnant females estrone caused excitation in 74% of the cells tested, while progesterone and testosterone, prolactin, and HCG were inhibitory in a majority of the cells tested, while progesterone and testosterone, prolactin, and HCG were inhibitory in a majority of the cells. In contrast, in males estrone caused excitation of only 19% but inhibition of 37%. A smaller percentage of cells was inhibited by progesterone, while the predominant response to testosterone was excitation. These results suggest that the pineal gland may be under …

Sleep Induction by Intranasal Application of Melatonin

The sleep inducing potency of melatonin was tested in a double-blind study against placebo. The application form was a nasal spray with a 0.85% solution of melatonin in ethanol. 70% of the subjects fell asleep after treatment with the hormone.

Alterations in the spontaneous activity of cells in the guinea pig pineal gland and visual system produced by pineal indoles

The indoles serotonin (SER), melatonin (MEL), 5-methoxytryptophol (5-MTL) and 5-hydroxytryptophol (5-HTL) were administered during daytime microelectrophoretically to 240 cells in the pineal gland of the guniea-pig. The action of SER and 5-HTL was predominantly depressant on the electrical activity, MEL and 5-MTL caused an excitation in most of the units. Although MEL and 5-MTL caused fairly similar reactions on average, they appear to act on different cells. The effects of microelectrophoretically applied MEL and 5-MTL on the spontaneous or evoked activity in the visual system (retinal ganglion cells, optic tract, lateral lateral geniculate body, superior colliculus) of the guinea-pig were…

Ultrastructural observations on the central innervation of the guinea-pig pineal gland.

In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between h…

Effects of an Earth-strength magnetic field on electrical activity of pineal cells

Although magnetic fields can influence biological systems, including those of man and other vertebrates1–5, no central nervous structure has been identified that might be involved in their detection. From a theoretical point of view, the pineal organ might be such a structure for the following reasons: (1) It is involved in the regulation of circadian rhythms6 and is thus essential for migratory restlessness (‘Zugunruhe’)7. Orientation at that time can be altered by an artificial magnetic field (MF) with a direction differing by 90° from that of the Earth. Circadian rhythms can be inhibited from phase shifting by compensation of the Earth's MF and can be influenced by an artificial MF8. (2)…

Morphological and electrophysiological evidence for habenular influence on the guinea-pig pineal gland

The central innervation of the guinea-pig pineal gland was investigated by histological and electrophysiological methods: Staining the pineal gland and the epithalamus, a double route of central innervation could be shown in the anterior part of the organ: (a) Fibres from the habenular nuclei, mainly from the lateral part, penetrate the organ via the pineal stalk. (b) Other fibres join the striae medullares and running in the habenulae reach the organ more dorsally. The fibres end in the intercellular space where they form a dense network. In 15 male guinea-pigs under urethane anesthesia, two series of unit recording experiments were performed: (a) Recordings were made from 128 units in the…

The Effects of Microelectrophoretically Applied Melatonin, Putative Transmitters, Thyroxine and Sex Hormones on the Electrical Activity of Pineal Cells in the Guinea-pig

ABSTRACT The effects of microelectrophoretic application of melatonin, noradrenaline, acetylcholine, thyroxine, testosterone and oestrone on pineal cell electrical activity were evaluated. With the exception of acetylcholine and oestrone pineal cells showed a circadian rhythm in sensitivity to the application of the substances. It is apparent from these studies, that (1) transmitters and hormones can bring about direct changes in the firing frequency of pineal cells, (2) all pineal cells do not respond to these substances in the same way and (3) that melatonin either produced in the pineal organ or reaching the gland via the general circulation may be capable of directly influencing the cel…