C. Demaine | King's College London (original) (raw)
Papers by C. Demaine
The effects of microelectrophoretic application of melatonin, noradrenaline, acetylcholine, thyro... more 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 cells engaged in its own synthesis or in the synthesis of other pineal antigonadotropins.
The Journal of physiology, 1974
The effects of locally applied melatonin on single neurones in the preoptic and anterior hypothal... more The effects of locally applied melatonin on single neurones in the preoptic and anterior hypothalamic areas of both rats and Syrian hamsters were evaluated. Responses of units in pinealectomised animals were compared with those obtained in sham operated animals. A total of 67 nerve cells were tested with melatonin, 29 in rats and 38 in hamsters. In rats, both excitatory and inhibitory responses to melatonin were observed regardless of whether the animals were pinealectomised or sham operated. In the sham operated hamsters, 70% of the cells tested responded to melatonin with an increased frequency of electrical discharge, whereas only inhibitory responses (67% of the cells tested) were recorded in pinealectomised animals. The results are consistent with the concept that the action of melatonin on the hypothalamus of intact hamsters is dependent on the level of activity of the pineal gland.
Neuroendocrinology, 1984
The effects of micro-electrophoretically applied pineal indoles, melatonin (MEL), 5-methoxytrypto... more The effects of micro-electrophoretically applied pineal indoles, melatonin (MEL), 5-methoxytryptophol (MTL) and 5-hydroxytryptophol (HTL) and of the neurotransmitters, noradrenaline (NOR), acetylcholine (ACH) and gamma-aminobutyric acid (GABA) on the electrical activity of pineal cells were studied in anaesthetized pigeons. Recordings were made from both sighted and blinded birds during both the day- and night-time. Both excitatory and inhibitory responses to the application of all substances tested were observed, while in all cases unresponsive cells were also found. The pattern of responses to MEL, MTL and to NOR varied significantly depending on whether the cells in the sighted pigeons were tested during the day or at night. This day/night rhythm of responses to MEL and to MTL also occurred in the blinded pigeons, although this was not the case for the effects of NOR. Units which were orthodromically excited by electrical stimulation of the habenular complex were also excited by ...
In a number of mammalian species, the pineal gland has been shown to mediate the inhibitory effec... more In a number of mammalian species, the pineal gland has been shown to mediate the inhibitory effects of short photoperiods on the secretion of several pituitary hormones. Although most studies have centred on gonadotropin secretion, in the last twenty five years there have been reports which have provided evidence for pineal-mediated inhibition of the production and release of each of the adenohypophyseal hormones (see review Mess et al., 1979). The Syrian hamster (Mesocricetus auratus) is a highly photosensitive species, in which the pineal can readily be shown to exert a dramatic and potent influence on the release of luteinising hormone (LH), follicle stimulating hormone (FSH) and prolactin (Reiter, 1980). Light restriction, obtained by blinding hamsters or placing them in continuous darkness or short photoperiod, results in reproductive involution. In males, after 50 days of light restriction, the testes are reduced to less than 20% of their original weight and do not produce spe...
Journal of Neurology Neurosurgery and Psychiatry, 1987
Twenty five patients with motor neuron disease completed a double blind randomised cross over tri... more Twenty five patients with motor neuron disease completed a double blind randomised cross over trial of RX77368, a stabilised TRH analogue, iv over 2 hours against saline. Temporary improvement in bulbar symptoms including speech, respiratory parameters, tongue movements and swallowing were seen. Fasciculations increased and spasticity decreased. Change in muscle force with drug was different from placebo but both increase
Journal of Comparative Physiology A, 1984
... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frank... more ... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frankfurt, Federal Republic of Germany 1 University of London, Chelsea College, Department of ... J Neural Transm 58:281-289 Semm P, Schneider T, Vollrath L, Wiltschko W (1982) Magnet-...
Journal of Steroid Biochemistry, 1984
Neuroscience, 1997
Melatonin binding in the brain of hydrocephalic H-Tx rats was examined by autoradiography. At the... more Melatonin binding in the brain of hydrocephalic H-Tx rats was examined by autoradiography. At the time of birth, hydrocephalic animals showed an abnormality in the distribution of high-affinity melatonin receptors dorsal to the cerebral aqueduct when compared to controls. Whereas newborn rats of the H-Tx strain that were unaffected by hydrocephalus had melatonin receptors in a tectal midsagittal strip overlying the aqueduct and spanning the anterior half of the tectum, hydrocephalic rats lacked melatonin receptors in the most anterior part of this region. In these animals, the length of the aqueduct over which receptors were missing was compressed and was additionally occluded by dystrophic ependyma. The first signs of ventricular expansion characteristic of hydrocephalus were evident.
The Journal of physiology, 1977
Progress in brain research, 1979
The Journal of physiology, 1976
The Journal of physiology, 1979
... A technique for the ejection of solutions from glass micropipettes, based on digitally contro... more ... A technique for the ejection of solutions from glass micropipettes, based on digitally controlled thermal expansion BY C. DEMAINE, M. FORSDYKE, HAZEL C. KANN* and DI WORMALD Department of Physiology, Basic Medical Sciences Group, Chelsea College, Manresa Road ...
Trends in Pharmacological Sciences, 1997
Physiology & Behavior, 1988
The temporal pattern of ultrasonic vocalizations by mice in an undisturbed 'home'... more The temporal pattern of ultrasonic vocalizations by mice in an undisturbed 'home' environment can now be assessed using a system based on amplitude discrimination. Within a chosen frequency band, vocalizations of sufficient intensity are detected by an amplitude discriminator. The output from a pulse generator is sent to a microcomputer which records the time of the incoming event. The system has been validated for monitoring ultrasonic vocalizations in the mouse.
Neuroscience Letters, 1985
The electrical activity of pigeon pineal cells was modified by gradual inversion of the natural m... more The electrical activity of pigeon pineal cells was modified by gradual inversion of the natural magnetic field. Effects were also found in blinded birds, and following surgical and chemical interference with the neural connections of the pineal, indicating that the gland possesses intrinsic magnetic sensitivity. The results are in line with the concept that magnetic field detection is associated with photoreceptor activity.
Neuroscience Letters, 1986
The effects of micro-electrophoretically applied melatonin on the electrical activity of Purkinje... more The effects of micro-electrophoretically applied melatonin on the electrical activity of Purkinje cells in the cerebellum of anaesthetized pigeons were studied. The proportion of excitatory and inhibitory responses to the pineal indoleamine varied significantly depending on whether the cells were tested during the day or at night. This day/night rhythm of responses was abolished if the birds were exposed to complete inversion of the vertical component of an artificial earth's strength magnetic field for one hour at 21.00 h. The results are in line with the concept that pineal involvement in endogenous central nervous rhythms is influenced by changes in the earth's magnetic field.
Neuroendocrinology, 1977
Electrophysiological techniques have been used to investigate the neural connections between the ... more Electrophysiological techniques have been used to investigate the neural connections between the amygdala and the rostral hypothalamus of female rats. Recordings have been made from 120 neurones in the preoptic/anterior hypothalamic area (POA/AHA) which could be driven by electrical stimulation of the amygdala. 89% of the neurones were activated orthodromically and, of these, 2 groups have been distinguished according to the latency of the responses. The remainder of identified cells were antidromically activated by stimulation of the amygdala. The response of these identified preoptic cells to the iontophoretic application of dopamine (DA) and noradrenaline (NA) has also been investigated. DA inhibited the spontaneous or glutamate-induced activity in 18 of 21 identified cells so tested and NA inhibited all 25 units; excitation was never observed. The role of the amygdala and of aminergic pathways in the control of ovulation is discussed.
Neuroendocrinology, 1981
The effects of microelectrophoretic application of thyroxin, thyrocalcitonin and parathormone on ... more The effects of microelectrophoretic application of thyroxin, thyrocalcitonin and parathormone on pineal cells of urethane anesthetized guinea pigs were evaluated. A total of 162 cells were tested with thyroxin, 122 of these units also being subjected to the microelectrophoresis of the indolamine melatonin. 68 cells were excited by the administration of thyroxin, 63 were inhibited while the remaining cells did not respond. 79% of the cells tested with both thyroxin and melatonin responded in a similar way to two substances. The responses to thyroxin varied significantly depending on whether the cells were tested during the day or at night. 104 pineal cells were tested with thyrocalcitonin, 20 U exhibiting an increased firing frequency, 58 showing an inhibitory response and the remaining 26 being unresponsive. Parathormone was applied to 64 pineal cells. Of the 43 cells responding to the hormone, 29 were excited and 14 showed decreased activity. In general, these results suggest that pineal cells may be subject to feedback control by the hormones of the thyroid and parathyroid glands.
The effects of microelectrophoretic application of melatonin, noradrenaline, acetylcholine, thyro... more 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 cells engaged in its own synthesis or in the synthesis of other pineal antigonadotropins.
The Journal of physiology, 1974
The effects of locally applied melatonin on single neurones in the preoptic and anterior hypothal... more The effects of locally applied melatonin on single neurones in the preoptic and anterior hypothalamic areas of both rats and Syrian hamsters were evaluated. Responses of units in pinealectomised animals were compared with those obtained in sham operated animals. A total of 67 nerve cells were tested with melatonin, 29 in rats and 38 in hamsters. In rats, both excitatory and inhibitory responses to melatonin were observed regardless of whether the animals were pinealectomised or sham operated. In the sham operated hamsters, 70% of the cells tested responded to melatonin with an increased frequency of electrical discharge, whereas only inhibitory responses (67% of the cells tested) were recorded in pinealectomised animals. The results are consistent with the concept that the action of melatonin on the hypothalamus of intact hamsters is dependent on the level of activity of the pineal gland.
Neuroendocrinology, 1984
The effects of micro-electrophoretically applied pineal indoles, melatonin (MEL), 5-methoxytrypto... more The effects of micro-electrophoretically applied pineal indoles, melatonin (MEL), 5-methoxytryptophol (MTL) and 5-hydroxytryptophol (HTL) and of the neurotransmitters, noradrenaline (NOR), acetylcholine (ACH) and gamma-aminobutyric acid (GABA) on the electrical activity of pineal cells were studied in anaesthetized pigeons. Recordings were made from both sighted and blinded birds during both the day- and night-time. Both excitatory and inhibitory responses to the application of all substances tested were observed, while in all cases unresponsive cells were also found. The pattern of responses to MEL, MTL and to NOR varied significantly depending on whether the cells in the sighted pigeons were tested during the day or at night. This day/night rhythm of responses to MEL and to MTL also occurred in the blinded pigeons, although this was not the case for the effects of NOR. Units which were orthodromically excited by electrical stimulation of the habenular complex were also excited by ...
In a number of mammalian species, the pineal gland has been shown to mediate the inhibitory effec... more In a number of mammalian species, the pineal gland has been shown to mediate the inhibitory effects of short photoperiods on the secretion of several pituitary hormones. Although most studies have centred on gonadotropin secretion, in the last twenty five years there have been reports which have provided evidence for pineal-mediated inhibition of the production and release of each of the adenohypophyseal hormones (see review Mess et al., 1979). The Syrian hamster (Mesocricetus auratus) is a highly photosensitive species, in which the pineal can readily be shown to exert a dramatic and potent influence on the release of luteinising hormone (LH), follicle stimulating hormone (FSH) and prolactin (Reiter, 1980). Light restriction, obtained by blinding hamsters or placing them in continuous darkness or short photoperiod, results in reproductive involution. In males, after 50 days of light restriction, the testes are reduced to less than 20% of their original weight and do not produce spe...
Journal of Neurology Neurosurgery and Psychiatry, 1987
Twenty five patients with motor neuron disease completed a double blind randomised cross over tri... more Twenty five patients with motor neuron disease completed a double blind randomised cross over trial of RX77368, a stabilised TRH analogue, iv over 2 hours against saline. Temporary improvement in bulbar symptoms including speech, respiratory parameters, tongue movements and swallowing were seen. Fasciculations increased and spasticity decreased. Change in muscle force with drug was different from placebo but both increase
Journal of Comparative Physiology A, 1984
... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frank... more ... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frankfurt, Federal Republic of Germany 1 University of London, Chelsea College, Department of ... J Neural Transm 58:281-289 Semm P, Schneider T, Vollrath L, Wiltschko W (1982) Magnet-...
Journal of Steroid Biochemistry, 1984
Neuroscience, 1997
Melatonin binding in the brain of hydrocephalic H-Tx rats was examined by autoradiography. At the... more Melatonin binding in the brain of hydrocephalic H-Tx rats was examined by autoradiography. At the time of birth, hydrocephalic animals showed an abnormality in the distribution of high-affinity melatonin receptors dorsal to the cerebral aqueduct when compared to controls. Whereas newborn rats of the H-Tx strain that were unaffected by hydrocephalus had melatonin receptors in a tectal midsagittal strip overlying the aqueduct and spanning the anterior half of the tectum, hydrocephalic rats lacked melatonin receptors in the most anterior part of this region. In these animals, the length of the aqueduct over which receptors were missing was compressed and was additionally occluded by dystrophic ependyma. The first signs of ventricular expansion characteristic of hydrocephalus were evident.
The Journal of physiology, 1977
Progress in brain research, 1979
The Journal of physiology, 1976
The Journal of physiology, 1979
... A technique for the ejection of solutions from glass micropipettes, based on digitally contro... more ... A technique for the ejection of solutions from glass micropipettes, based on digitally controlled thermal expansion BY C. DEMAINE, M. FORSDYKE, HAZEL C. KANN* and DI WORMALD Department of Physiology, Basic Medical Sciences Group, Chelsea College, Manresa Road ...
Trends in Pharmacological Sciences, 1997
Physiology & Behavior, 1988
The temporal pattern of ultrasonic vocalizations by mice in an undisturbed 'home'... more The temporal pattern of ultrasonic vocalizations by mice in an undisturbed 'home' environment can now be assessed using a system based on amplitude discrimination. Within a chosen frequency band, vocalizations of sufficient intensity are detected by an amplitude discriminator. The output from a pulse generator is sent to a microcomputer which records the time of the incoming event. The system has been validated for monitoring ultrasonic vocalizations in the mouse.
Neuroscience Letters, 1985
The electrical activity of pigeon pineal cells was modified by gradual inversion of the natural m... more The electrical activity of pigeon pineal cells was modified by gradual inversion of the natural magnetic field. Effects were also found in blinded birds, and following surgical and chemical interference with the neural connections of the pineal, indicating that the gland possesses intrinsic magnetic sensitivity. The results are in line with the concept that magnetic field detection is associated with photoreceptor activity.
Neuroscience Letters, 1986
The effects of micro-electrophoretically applied melatonin on the electrical activity of Purkinje... more The effects of micro-electrophoretically applied melatonin on the electrical activity of Purkinje cells in the cerebellum of anaesthetized pigeons were studied. The proportion of excitatory and inhibitory responses to the pineal indoleamine varied significantly depending on whether the cells were tested during the day or at night. This day/night rhythm of responses was abolished if the birds were exposed to complete inversion of the vertical component of an artificial earth's strength magnetic field for one hour at 21.00 h. The results are in line with the concept that pineal involvement in endogenous central nervous rhythms is influenced by changes in the earth's magnetic field.
Neuroendocrinology, 1977
Electrophysiological techniques have been used to investigate the neural connections between the ... more Electrophysiological techniques have been used to investigate the neural connections between the amygdala and the rostral hypothalamus of female rats. Recordings have been made from 120 neurones in the preoptic/anterior hypothalamic area (POA/AHA) which could be driven by electrical stimulation of the amygdala. 89% of the neurones were activated orthodromically and, of these, 2 groups have been distinguished according to the latency of the responses. The remainder of identified cells were antidromically activated by stimulation of the amygdala. The response of these identified preoptic cells to the iontophoretic application of dopamine (DA) and noradrenaline (NA) has also been investigated. DA inhibited the spontaneous or glutamate-induced activity in 18 of 21 identified cells so tested and NA inhibited all 25 units; excitation was never observed. The role of the amygdala and of aminergic pathways in the control of ovulation is discussed.
Neuroendocrinology, 1981
The effects of microelectrophoretic application of thyroxin, thyrocalcitonin and parathormone on ... more The effects of microelectrophoretic application of thyroxin, thyrocalcitonin and parathormone on pineal cells of urethane anesthetized guinea pigs were evaluated. A total of 162 cells were tested with thyroxin, 122 of these units also being subjected to the microelectrophoresis of the indolamine melatonin. 68 cells were excited by the administration of thyroxin, 63 were inhibited while the remaining cells did not respond. 79% of the cells tested with both thyroxin and melatonin responded in a similar way to two substances. The responses to thyroxin varied significantly depending on whether the cells were tested during the day or at night. 104 pineal cells were tested with thyrocalcitonin, 20 U exhibiting an increased firing frequency, 58 showing an inhibitory response and the remaining 26 being unresponsive. Parathormone was applied to 64 pineal cells. Of the 43 cells responding to the hormone, 29 were excited and 14 showed decreased activity. In general, these results suggest that pineal cells may be subject to feedback control by the hormones of the thyroid and parathyroid glands.