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D P Cardinali

Publications and source records attributed to D P Cardinali.

At least 199 records · Page 11Linked to original sources
PubMed1981

Melatonin increases cGMP and decreases cAMP levels in rat medial basal hypothalamus in vitro.

Measurement of cyclic nucleotide accumulation in rat medial basal hypothalamus (MBH) incubated in vitro with methoxyindoles indicated that melatonin (10(-8) M or greater) increased significantly cGMP and depressed cAMP levels. Only the effect on MBH cAMP was shared by 5-methoxytryptophol which exhibited a greater activity than melatonin. 6-Fluoromelatonin (10(-7) M) increased cGMP, whereas the effect of 6-hydroxymelatonin was not significant. Both 6-fluoro- and 6-hydroxymelatonin (10(-5) M) depressed MBH cAMP accumulation while only 6-fluoromelatonin affected it at 10(-7) M concentrations. These data suggest that melatonin and 5-methoxytryptophol affect differently cyclic nucleotide content of MBH at physiological concentrations.

Animals↗
PubMed1981

The sympathetic superior cervical ganglia as peripheral neuroendocrine centers.

The superior cervical ganglia (SCG) provide sympathetic innervation to the pineal gland, cephalic blood vessels, the choroid plexus, the eye, carotid body and the salivary and thyroid glands. Removal of the ganglia brings about several neuroendocrine changes in mammals, including the disruption of water balance in pituitary stalk-sectioned rats, and the alteration of normal photoperiodic control of reproduction in hamsters, ferrets, voles, rams and goats. These effects are commonly attributed to pineal denervation. However pinealectomy does not always mimic ganglionectomy in its neuroendocrine sequelae. This paper discusses several examples illustrating the lack of homology of ganglia and pineal removal, including the prolactin release brought about by gonadal steroids in spayed rats, the changes in drinking behaviour caused by ganglionectomy and the control of goitrogenic response to methylmercaptoimidazole in rats. All these examples indicate that SCG removal, at least as far as for neuroendocrinologists and pineal experimenters are concerned, should not be considered simply as "pineal denervation". A functionally relevant link between SCG and the hypothalamus may occur in rats inasmuch as ganglionectomy depresses norepinephrine uptake and increases the number and responses of alpha-adrenoceptors in medial basal hypothalamus. Lastly the SCG are active points of concurrency for hormone signals, as revealed by the metabolic changes induced by steroid and anterior pituitary hormones in these structures even in the absence of intact preganglionic connections, as well as by the existence of putative receptors for some of the hormones, namely, estradiol, testosterone and corticosteroids. The SCG appear to constitute a peripheral neuroendocrine center.

Animals↗
PubMed1981

Changes in drinking behavior caused by superior cervical ganglionectomy and pinealectomy in rats.

The effect of superior cervical ganglionectomy (SCGx) or pinealectomy (Px) on drinking behavior was examined in rats subjected to a restricted photoperiod (i.e. 4 h of light per day). Both in male and female rats SCGx depressed water intake significantly from 1 to 3 days after surgery. After osmolar (i.p. 5% NaCl) or non-osmolar stimuli (s.c. isoproterenol) SCGx female rats exhibited a depressed response in water and NaCl intake, an effect not observed in male rats. Castration of male or female rats did not change their drinking behavior response to thirst stimuli. Px did not mimic SCGx in its effects on drinking behavior; moreover in sham-Px rats the water intake fell significantly after craniotomy. Following the injection of isoproterenol or i.p. hypertonic saline, the drinking behavior was the same in Px or sham-Px animals. To assess whether the effects of SCGx needed the presence of the pineal gland, Px or sham-Px rats were subjected to SCGx 9 days later. In both groups SCGx depressed water intake; however the inhibition that followed ganglia removal in Px rats was greater than that observed in animals with a pineal gland. Water and NaCl intake following isoproterenol or i.p. hypertonic saline were similar in both experimental groups. These results suggest that SCGx affects drinking behavior in part by pathways other than pineal denervation.

Animals↗
PubMed1981

Prostaglandin E2 increases adenosine 3',5'-monophosphate concentration and binding-site occupancy, and stimulates serotonin-N-acetyltransferase activity in rat pineal glands in vitro.

The effects of prostaglandins (PGs) on rat pineal metabolism were examined in vitro. PGE2 (0.01-1 microM) increased the activity of serotonin-N-acetyltransferase (SNAT), the stimulation curve exhibiting a maximum at 0.1 microM. PGE1 increased SNAT activity only at the highest dose (1 microM) whereas PGF2 alpha, 15-keto-PGF2 alpha or PGI2 did not affect the enzymic activity. The stimulation of SNAT activity brought about by PGE2 in pineals from ganglionectomized rats was greater than in sham-operated controls at all the doses studied, suggesting that the observed effect is predominantly post-synaptic. Only PGE2 significantly increased pineal cAMP accumulation in vitro at doses between 0.01 and 1 microM, and depressed the unoccupied cAMP-binding sites in pineal 900 g supernatants. The total number of cAMP-binding sites remained unaltered after incubation of PGE2. The present observations together with the previously reported NE-induced release of PGs in incubated pineal glands, the occurrence of pineal PG-binding sites and the indomethacin blockade of the nocturnal rise of pineal SNAT and melatonin content, support a role for PGs in the control of melatonin synthesis.

Acetyltransferases↗
PubMed1980

Prostaglandin E release by rat medial basal hypothalamus in vitro. Inhibition by melatonin at submicromolar concentrations.

Melatonin depressed PGE release by rat medial basal hypothalamus (MBH) in vitro at concentrations 10(-8) M or greater. The two-fold increase in PGE release induced by adding 10(-4) M norepinephrine to MBH explants was also impaired by melatonin at micromolar or greater concentrations. These data support the view that melatonin is a physiological inhibitor of PG synthesis in MBH.

Animals↗
PubMed1980

Changes in total and polymerized tubulin of the medial basal hypothalamus and adenohypophysis of castrated or hormone-injected rats.

Treatment of orchidectomized rats with LH, FSH or prolactin decreased the tubulin content of the medial basal hypothalamus (MBH), whereas FSH or prolactin augmented it in the adenohypophysis (AH). After castration, negative correlations existed between serum LH and total or polymerized MBH tubulin, whereas in the AH positive correlations were found. After estradiol-progesterone treatment of spayed rats a significant correlation was found between serum LH and the percentage of AH tubulin in the polymerized form.

Animals↗
PubMed1980

Melatonin blocks in vitro generation of prostaglandin by the uterus and hypothalamus.

The effects of melatonin on the motility (isometric tension developed and contractile frequency) of uterine horns isolated from ovariectomized rats as well as on the mechanical responsiveness to added oxytocin or prostaglandin F2 alpha (PGF2 alpha) were explored. The pineal indole (10(-6) M or higher) depressed significantly the spontaneous motility of the uterus and reduced the responses evoked by oxytocin but not those evoked by PGF2 alpha. Melatonin was also tested on the prostaglandin (PG) release into the suspending media from either uterine horns from spayed rats or bovine medial basal hypothalamic (MBH) explants. Melatonin (10(-3) M) diminished the output from the uterus or the MBH of both PGE and PGF-"like material". Similarities between the effects of melatonin and indomethacin as well as the possible physiological relevance of the present findings are discussed.

Animals↗
PubMed1980

Dihydroergocryptine binding sites in bovine and rat pineal glands.

High affinity binding of [3H]dihydroergocryptine (DHE) to crude membrane preparations of bovine and rat pineal glands was examined by a rapid filtration procedure through Whatman GFB paper. Scatchard analysis of bovine pineal membranes revealed a single population of binding sites with Kd = (4.8 +/- 1.9) X 10(-8) M (mean +/- S.E.M., n = 3) and binding site concentration = 834 +/- 103 fmol/mg of protein. When various alpha- and beta-adrenergic agonists or antagonists were tested for their ability to inhibit [3H]DHE binding the following Ki values (microM) were obtained: DHE (0.039), phentolamine (0.102), phenoxybenzamine (0.262), methysergide (0.670), L-epinephrine (2.27), serotonin (3.09), L-norepinephrine (3.20), octopamine (30.3), L-propranolol (1710), L-isoproterenol (greater than 2000). In order to obtain information on the pre- or postsynaptic location of pineal DHE binding sites, pineal 900 g supernatants were prepared from rats subjected to bilateral superior cervical ganglionectomy or sham-operation 7 days earlier. Ganglionectomy caused a 53% increase in the number of binding sites without changing significantly their Kd (5.2 X 10(-8) M and 5.5 X 10(-8) M in ganglionectomized and control rats, respectively). These results are compatible with the view that postsynaptic alpha-adrenoceptors are present in the pineal gland.

Animals↗
PubMed1980

Effect of indomethacin on monoamine metabolism and melatonin synthesis in rat pineal gland.

Indomethacin treatment of rats resulted in a significant increase of pineal monoamine oxidase (MAO) type A activity, whereas it depressed MAO type B and hydroxyindole-O-methyl transferase activities. Indomethacin also significantly impaired the nocturnal rise of pineal serotonin-N-acetyltransferase activity and melatonin content. These results suggest a role for prostaglandins in the regulation of pineal function.

Acetylserotonin O-Methyltransferase↗
PubMed1980

Binding sites for melatonin in bovine pineal gland.

High-affinity binding of melatonin to crude membrane preparations of bovine pineal gland was examined by a rapid filtration procedure through Whatman GFB paper. Maximal melatonin binding was attained in 60 min at 37 degrees C, in 2 h at 25 degrees C and in 5 h at 0 degree C; at 25 and 37 degrees C it was 36 and 42% of that at 0 degree C. Specific binding was thermolabile and decreased following incubation with trypsin; it was also pH dependent, the maximum being observed at physiological pH. Melatonin binding was inhibited by the addition of monovalent or divalent ions to the incubation buffer. Subcellular fractionation studies indicated that 39 and 50% of binding was located in the pellets at 900 and 27,000 g whereas 11% was detected in the microsomal pellet. Scatchard analysis revealed a single population of binding sites with Kd = (7.0 +/- 1.5) 10(-7) M (mean +/- SEM, n = 4); binding site concentration ranged from 185 to 356 fmol/mg of protein. When various melatonin analogues were tested for their ability to inhibit (3H)-melatonin binding, the following Ki values (10(-7) M), were obtained: N-acetyl-serotonin 120, serotonin 130, 2-methyl indole 154, 5-hydroxytryptophol 218, 5-methoxytryptamine 266, 5-methoxytryptophol 660, tryptamine 1,740, 5-hydroxyindole acetic acid 3,455, 5-methoxyindole acetic acid 12,690, 5-hydroxytryptophan 13,600, and 6-hydroxymelatonin 55,550. Those results suggest that melatonin receptors may be present in the pineal gland.

Animals↗
PubMed1980

[3H]Dihydroergocryptine binding in anterior pituitary and prolactin secretion: further evidence of brain regulation of adenohypophyseal receptors.

Secretion of PRL by the pituitary gland is under tonic inhibitory control by tuberoinfundibular dopaminergic neurons. The aim of the present work was to assess the influence of the hypothalamus on the binding of [3H]dihydroergocryptine, a dopamine agonist, in the adenohypophysis and its role in the hypoprolactinemic action of exogenous dopamine. Serum PRL levels were elevated in ovariectomized adult rats with electrolytic lesions of the median eminence compared to levels in sham-operated animals; [3H]dihydroergocryptine binding to anterior pituitary was elevated from a control value of 161.2 +/- 7.7 to 229.0 +/- 10.0 fmol/mg protein in rats studied 7-21 days after placement of the lesion (P < 0.05). Scatchard analysis of [3H]dihydroergocryptine binding in lesioned and sham-operated animals indicated an increase of 62% in the number of binding sites without a change in binding affinity. In a second group of rats, with or without median eminence destruction, the effects of different doses of ip dopamine on serum PRL were determined. The hypoprolactinemic effect of each dose of the amine was more evident in median eminence-lesioned rats than in sham-operated controls. These results suggest that when hypothalamic influences on the anterior pituitary are removed, there is increased binding of dopamine by the gland and increased hypoprolactinemic effects of the exogenous amine. This indicates that receptors in the pituitary are under hypothalamic control, and this could be an important regulatory mechanism in neuroendocrine events.

Animals↗