FLUORIDE ACTION NETWORK PESTICIDE PROJECT

Return to FAN's Pesticide Homepage

Return to Abstracts Page


Pineal Gland Abstracts: 1993

Note: the following is a limited selection of abstracts available at PubMed, Science Direct, and Toxnet.

Abstracts on the Pineal Gland by Year
-
2005
(Jan-June)
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
Up to 1989

 

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7678217&dopt=Abstract

Endocrinology 1993 Jan;132(1):285-92

Prolonged exposure to melatonin leads to time-dependent sensitization of adenylate cyclase and down-regulates melatonin receptors in pars tuberalis cells from ovine pituitary.


Hazlerigg DG, Gonzalez-Brito A, Lawson W, Hastings MH, Morgan PJ.

Department of Anatomy, University of Cambridge, United Kingdom.

In photoperiodic mammals, seasonal cycles of growth and reproduction are cued by changes in the duration of the nocturnal profile of secretion of the pineal hormone melatonin. To investigate the likely mode of action of this hormone on target tissues, the effect of prolonged treatment with melatonin on the sensitivity of the adenylate cyclase (AC) system was examined in primary cultures of ovine pars tuberalis (PT) cells. When cells were exposed to melatonin (100 pM or 1 microM) for 16 h, and the hormone was then removed by a series of washes, basal production of cAMP was elevated over that observed in cells not treated with melatonin. Moreover, the rate of accumulation of cAMP after stimulation with forskolin (1 microM) was markedly enhanced in cells previously treated with melatonin compared to that in untreated controls. This sensitization by melatonin of the basal and forskolin-stimulated responses developed gradually and was half-maximal after approximately 8 h of exposure. There was no significant difference between the sensitizing effects of the two melatonin concentrations used. Treatment with melatonin for 24 h reduced the total amount of specific [125I]iodomelatonin binding in PT cell membranes by 30-50%. However, over the same period there was no reduction in the ability of a maximal (1 microM) concentration of melatonin to inhibit forskolin-stimulated cAMP production, indicating the presence of an excess capacity of melatonin receptors in cultured PT cells. Nevertheless, treatment with melatonin for 16 h did result in a 10-fold increase in the IC50 for the inhibition by melatonin of forskolin-stimulated cAMP production. The enhancement of cAMP production after prolonged treatment with melatonin was not masked by the inclusion of isobutylmethylxanthine (1 mM) during the subsequent challenge with forskolin, suggesting that sensitization was not due to a reduction in the activity of cAMP-phosphodiesterase. In control cells, aluminium fluoride caused an inhibition of forskolin-stimulated cAMP production. Prolonged treatment with melatonin abolished the inhibitory effect of aluminium fluoride, suggesting that treatment with melatonin caused a shift in the net balance between the G-protein-mediated stimulatory and inhibitory influences on the AC system. The sensitization of AC was not blocked by the inclusion of cycloheximide (10 micrograms/ml) during prolonged exposure to melatonin, suggesting that de novo protein synthesis is not a requirement for this effect of the hormone. These results constitute the first demonstration of an independent action of melatonin on ovine PT cells that is dependent upon the duration of the endocrine stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)

PMID: 7678217 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8225803&dopt=Abstract

Int J Neurosci 1993 Sep;72(1-2):95-106

Multiple sclerosis: the role of the pineal gland in its timing of onset and risk of psychiatric illness.


Sandyk R, Awerbuch GI.

NeuroCommunication Research Laboratories, Danbury, CT 06811.

The incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. It has been suggested, therefore, that the clinical manifestation of MS is dependent upon having passed the pubertal period. Since pineal melatonin secretion declines from childhood to puberty and as melatonin is an immunomodulator, we have proposed that the dramatic decline in melatonin secretion just prior to the onset of the physical manifestations of puberty may disrupt immune responses resulting in either reactivation of the infective agent or in an increased susceptibility to post-pubertal infection. The fall in melatonin secretion during pre-puberty may also increase the susceptibility of these patients to affective disorder which is associated with lower melatonin secretion and the presence of a phase-advance of their biological rhythms. We predicted, therefore, a higher incidence of affective disorder in patients with pubertal or post-pubertal onset of MS compared to those in whom the disease manifested later. To test this hypothesis, we studied the incidence of affective disorder in relation to age of onset of first neurological symptoms in 31 MS patients, 6 of whom manifested symptoms of MS prior to age 18 (mean = 16.8 years). All patients with pubertal onset MS and only 48% of the control group had an affective disorder. The pubertal onset patients also had a significantly lower nocturnal melatonin levels and a lower incidence of pineal calcification on CT scan. These findings thus support the hypothesis implicating the pineal gland in the timing of onset of MS and in the risk for the development of affective disorder.

PMID: 8225803 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8381851&dopt=Abstract

J Inorg Biochem 1993 Feb 15;49(3):209-20

Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland.


Bocchi G, Valdre G.


Dipartimento di Scienze Mineralogiche, Universita di Bologna, Italy.

Physical, chemical, and mineralogical investigations of mineral concretions found in the human pineal gland were performed by means of optical microscopy and modern techniques of analytical electron microscopy and x-ray powder diffraction (OM,SEM + EDS,TEM + EDS,XRD). The mineral concretions were found to be nano-crystalline carbonate-hydroxyapatite with a mean Ca/P molar ratio equal to 1.65, very close to the theoretical value of 1.67. TEM and XRD showed that this is the only inorganic phase present in the concretions without the presence of amorphous phosphate as precursor. SEM and EDS, performed on cross-sectioned samples, showed a concentric layered distribution of the inorganic phase permeated by organic matter, within the concretions, with a slight increasing of the Ca/P molar ratio in their internal part.

PMID: 8381851 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8152603&dopt=Abstract

Neurosci Lett. 1993 Dec 24;164(1-2):213-6.

Neural projections of the pineal organ in the larval sea lamprey (Petromyzon marinus L.) revealed by indocarbocyanine dye tracing.

Yanez J, Anadon R, Holmqvist BI, Ekstrom P.

Max-Planck Institute for Physiological and Clinical Research, W.G. Kerckhoff-Institute, Bad Nauheim, FRG.

The distribution of the central neural connections of the pineal organ of the larval sea lamprey was investigated by means of anterograde and retrograde tracing with the fluorescent lipophilic dye, DiI (1,1'-dioctadecyl 3,3,3',3'-tetramethylindocarbocyanine perchlorate). Pinealofugal projections are well developed in larvae, extending from the posterior commissure into the diencephalon and mesencephalon. Small numbers of neurons were retrogradely labelled in the transition zone between the diencephalon and the mesencephalic tegmentum. These cells may constitute the first pinealopetal system described in anamniotes.

PMID: 8152603 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8281527&dopt=Abstract

Cancer Genet Cytogenet. 1993 Dec;71(2):185-6.

Chromosomal abnormalities in a pineocytoma.

Bello MJ, Rey JA, de Campos JM, Kusak ME.

Publication Types: Letter

PMID: 8281527 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8397338&dopt=Abstract

Nature. 1993 Sep 23;365(6444):314-20.
Adrenergic signals direct rhythmic expression of transcriptional repressor CREM in the pineal gland.

Stehle JH, Foulkes NS, Molina CA, Simonneaux V, Pevet P, Sassone-Corsi P.

CNRS URA 1332, Universite Louis Pasteur, Strasbourg, France.

Transcription factor CREM appears to play a key physiological and developmental role within the hypothalamic-pituitary-gonadal axis. This axis is modulated by the pineal hormone melatonin, whose production is in turn driven by the endogenous clock. There is striking circadian fluctuation of a novel CREM isoform, ICER, which is expressed at high levels during the night. ICER is generated from an alternative, intronic promoter and functions as a powerful repressor of cyclic AMP-induced transcription. Rhythmic adrenergic signals originated by the clock direct ICER expression by stimulation of the cAMP signal transduction pathway.

PMID: 8397338 [PubMed - indexed for MEDLINE]