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D P Cardinali

Publications and source records attributed to D P Cardinali.

At least 163 records · Page 9Linked to original sources
PubMed1985

Changes in parathyroid hormone and calcium levels after superior cervical ganglionectomy of rats.

To assess the role of peripheral sympathetic nerves in the regulation of parathyroid hormone (PTH) release rats subjected to bilateral superior cervical ganglionectomy (SCGx) 8-24 h earlier were used. SCGx did not result in significant changes of basal serum calcium (Ca) or immunoreactive PTH (iPTH) levels. The i.p. administration of EDTA every 30 min for up to 3 h brought about an impending decrease of serum Ca levels in both sham-operated and SCGx rats when assessed 23 h after surgery. The extent of hypocalcemia was significantly larger in the SCGx group. In sham-operated controls serum iPTH increased by 32-145%, 1-3 h after beginning EDTA treatment whereas such increases were considerably lower or absent in SCGx rats. In 3 out of 7 SCGx animals that survived to a double EDTA dose, iPTH increased to levels indistinguishable from controls. When SCGx rats subjected to surgery 23 h earlier and receiving d-1-propranolol (5 mg/kg) or phentolamine (10 mg/kg) 4 h and 30 min earlier were submitted to iterative EDTA injection serum iPTH increased, whereas no changes were detected in SCGx rats treated with vehicle and subjected to the same EDTA treatment. These data indicate that (1) SCGx does not affect basal release of iPTH or serum Ca concentration; (2) 23-26 h after SCGx there is a significant impairment of homeostatic iPTH responses to low Ca levels which can be overcome by suitable Ca stimulus; (3) circulating catecholamines may affect denervated parathyroid cells, as revealed by the changes in serum iPTH and Ca elicited by alpha- and beta-adrenoceptor-blocker treatment of SCGx rats.

Animals↗
PubMed1985

Role of the sympathetic nervous system in the control of thyroid compensatory growth of normal and hypophysectomized rats.

Compensatory thyroid growth in rats subjected to unilateral thyroidectomy (Tx) and superior cervical ganglionectomy (SCGx) performed ipsilaterally to the remaining lobe was about 2-fold that of rats subjected hemiTx alone, when assessed 7-15 days after surgery. HemiTx depressed serum T4 levels by 33% and increased serum TSH by 80% in control rats. Unilateral SCGx, which did not affect circulating T4 or TSH by itself, prevented hemiTx-induced changes of hormone levels. After hypophysectomy (Hpx) thyroid involution ensued. The subsequent hemiTx of Hpx rats did not affect Hpx-induced thyroid regression 7 days later, but abolished it 15 days later. At this time a factorial analysis of variance revealed lack of significant interaction between Hpx and hemiTx thus suggesting that a similar thyroid growth ensues after hemiTx regardless of pituitary intactness. However, both serum T4 and TSH levels were very low in Hpx rats regardless of whether one or two thyroid lobes were present indicating that thyroid growth in the absence of pituitary was not accompanied by increased secretory activity. SCGx performed ipsilaterally to the remaining lobe blunted the growth of the lobe in Hpx hemiTx rats. Moreover, the denervated thyroid lobe regressed in Hpx rats to values significantly lower than those of Hpx rats having intact sympathetic nerves both in the presence or in the absence of a contralateral thyroid lobe. SCGx did not modify the very low serum TSH and T4 levels of Hpx rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Benzodiazepines decrease norepinephrine release from rat pineal nerves by acting on peripheral type binding sites.

In 3 000g-supernatants of rat pineal homogenates a single population of benzodiazepine (BZP) binding sites with dissociation constant= 97-102 nM and maximal number of sites= 6.5-9 pmoles/mg protein was detected by employing 3H-flunitrazepam (FNZP) as a radioligand. The following order of affinity for several BZP was found (Ki, nM): Ro 5-4864 (8), FNZP (99), clonazepam (7,900) Ro 15-1788 (10,000). Two weeks after bilateral superior cervical ganglionectomy (SCGx) a 18-28% reduction of site number without significant changes in affinity of 3H-FNZP binding was detectable in rat pineal glands. In pineal explants priorly incubated with 3H-norepinephrine, exposure to 0.1-10 microM of Ro 5-4864 or diazepam decreased significantly transmitter release elicited by 80 mM K+, whereas clonazepam did not affect it significantly. At 10 microM-concentrations, Ro 5-4864, diazepam or clonazepam increased pineal melatonin content of explants incubated for 6 h with the drug. In pineal explants of rats subjected to SCGx 14 days earlier, only 10 microM of Ro 5-4864 increased melatonin content significantly to about half of the percent increase detected in innervated glands. These results suggest that BZP decrease transmitter release from pineal sympathetic nerves by acting on peripheral BZP binding sites, an effect which is about 2 orders of magnitude greater than the postsynaptic stimulation of pineal melatonin synthesis.

Animals↗
PubMed1984

Benzodiazepine binding sites in human pineal gland.

The high affinity binding of [3H]flunitrazepam (FNZP) to crude membrane preparations was examined in human pineal glands. Scatchard analysis of the data at equilibrium revealed a single population of binding sites with dissociation constant = 2.36-2.53 nM and binding site concentration = 59-108 fmol/mg protein. When various benzodiazepine (BZP) analogues were tested for their ability to inhibit [3H]FNZP binding the following Ki (nM) were found: clonazepam (0.13), RO 15-1788 (0.60), FNZP (2.14), diazepam (13.5), Ro 5-4864 (greater than 10 000). In both human pineal gland and cerebral cortex 10-100 microM gamma-aminobutyric acid (GABA) increased BZP binding by about 30%, an effect inhibited by the GABA receptor blocker bicuculline. The stimulatory effect of GABA on [3H]FNZP binding in rat cerebral cortex (about 60%) decreased as a function of time elapsed postmortem at room temperature to reach values similar to those observed in human brains. These results suggest the existence of central type BZP receptors in the human pineal glands.

Adolescent↗
PubMed1984

Acute superior cervical ganglionectomy depresses the postcastration rise of gonadotropins in male rats.

In male rats, superior cervical ganglionectomy (SCGx) delayed the rise of serum FSH and LH induced by orchidectomy by 24 h. SCGx resulted in a decrease of median eminence norepinephrine (NE) content 16 h after surgery and in an increase of medio-basal hypothalamic cAMP synthesis and receptor occupancy. These data indicate that NE release from degenerating terminals originating in the superior cervical ganglion neurons modifies the regulatory mechanisms controlling the rise of gonadotropins after orchidectomy in rats.

Animals↗
PubMed1984

Pineal methoxyindoles depress calcium uptake by rat brain synaptosomes.

The effect of several pineal methoxyindoles on 45Ca2+-uptake was examined in a crude synaptosome preparation from adult rat brains. 5-Methoxytryptol, 5-methoxytryptamine, melatonin and 6-chloromelatonin (10(-8)-10(-6) M) depressed significantly the K+-stimulated increase in Ca2+-uptake, without affecting the basal, unstimulated Ca2+-uptake by synaptosomes. At 10(-6) M concentration the following order of potency was found: 6-chloromelatonin greater than or equal to 5-methoxytryptamine greater than 5-methoxytryptophol greater than or equal to melatonin. Serotonin did not affect significantly either basal or stimulated Ca2+-uptake.

5-Methoxytryptamine↗
PubMed1984

Effect of naloxone on the nocturnal rise of rat pineal melatonin content.

Rats exposed to 14 light: 10 h dark photoperiods were given naloxone hydrochloride (10 mg/kg) s.c. 2 h before and 5 h after the lights were turned off. A smaller nocturnal pineal melatonin peak, as well as a slower decrease from peak values were observed in naloxone-treated rats. Naloxone (up to 10(-4) M) did not affect either in vitro rat pineal melatonin content or 3H-labeled transmitter release in glands previously incubated with [3H]norepinephrine. Hence a central, rather than a peripheral opioid synapse appears to be involved in naloxone effect on nocturnal melatonin increase.

Animals↗
PubMed1984

Pineal--related changes in cyclic AMP levels of rat medial basal hypothalamus.

Pinealectomy (Px) in adult male rats resulted in increased cyclic AMP accumulation by medial basal hypothalamic (MBH) explants 3 and 7 days after surgery. 24 h after superior cervical ganglionectomy (Gx) an augmented MBH cyclic AMP accumulation was observed. The effects of Px and Gx were additive, as revealed in animals subjected to Gx 3 days after Px.

Animals↗
PubMed1984

A developmental study of adenohypophyseal dopaminergic receptors and of haloperidol-induced prolactin release in rats.

The ontogenesis of adenohypophyseal dopamine receptors, assessed by haloperidol-displaceable [3H]didydroergocryptine (DHE) binding of 1-, 12-, 20-, 28-day-old female rats was studied in correlation with the prolactin releasing effect of haloperidol (1 mg/kg), a dopaminergic antagonist. A specific dopaminergic receptor could be quantified at the time of birth (Bmax = 2.5 +/- 0.5 fmol/mg; Kd = 1.5 +/- 0.2 microM), anterior pituitary receptor density (fmol bound/mg) increased non-significantly henceforth and a slight ontogenic increase of Kd values was also observed. Haloperidol failed to increase prolactin in newborn female rats; at 4 days, a significant increase was evidenced, and from then onwards the response rose markedly with age. As sex differences in the dopaminergic modulation of prolactin release have been documented, the hyperprolactinemic effect of haloperidol in correlation with [3H]DHE binding in anterior pituitary of 28-day-old female and male rats was studied. Though the prolactinemic increment achieved by haloperidol was significantly higher in female than in male rats, [3H]DHE binding was not statistically different between sexes. These data indicate: (a) a specific binding site for [3H]DHE in anterior pituitary of female rats is present from the first postnatal days. From then onwards, a gradual but slight increment in both, Bmax and Kd for the dopaminergic agonist is observed until puberty; (b) at 28 days, no clear difference in Bmax and Kd is present in [3H]DHE binding between male and female rats; (c) by contrast, haloperidol shows a prolactin releasing effect that increases markedly with age in the female.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

In vitro uptake of benzodiazepines by rat pineal gland.

As a part of a study aiming to characterize the physiological and pharmacological significance of the high affinity pineal benzodiazepine (BZP) binding sites reported previously, we examined the uptake of the BZP derivative 3H-flunitrazepam (FNZP) by rat pineal glands in vitro. At 37 degrees C, 3H-radioactivity was taken up by tissue up to a pineal/medium concentration of about 12, while at 0 degrees C the uptake amounted to only one-third that at 37 degrees C. Reciprocal of uptake analyzed by Lineweaver-Burk plots indicated apparent Km's of 1.74 and 1.45 microM, and Vmax's of 1.32 and 1.04 pmol per min per mg tissue, for control and superior cervical ganglionectomized rats, respectively, suggesting that the neural compartment does not participate significantly in 3H-FNZP uptake. Cerebral cortex explants of similar size and weight as the pineal ones took up 3H-FNZP to a maximum tissue/medium concentration of about 2. Neither pineal nor cerebral cortex 3H-radioactivity uptake exhibited significant changes as a function of time of day. A number of agents, including several BZP analogues, cocaine, desipramine, melatonin, fluoxetine, nomifensine, and dipiridamol, as well as changes in the ionic environment or metabolic inhibitors, did not affect 3H-FNZP uptake significantly. Other tissues, such as liver, muscle, kidney, adrenal gland, or anterior pituitary, took up 3H-radioactivity to tissue concentrations slightly lower than those of the cerebral cortex, suggesting that drug liposolubility accounted only to a limited extent for the high in vitro uptake detected in incubated pineals.

Animals↗
PubMed1984

Melatonin inhibits beta-adrenoceptor-stimulated cyclic AMP accumulation in rat astroglial cell cultures.

We investigated whether astroglial cells are a site of action for the effect of melatonin on brain cyclic AMP content. Rat astroglial cell subcultures, identified according to morphological and immunochemical criteria, were used. Addition of melatonin to the cultures did not result in changes of cyclic AMP content. However, melatonin at 0.1-1 microM concentrations was able to impair the cyclic AMP increase elicited by 1 microM norepinephrine or isoproterenol in astroglial cultures. This melatonin effect was also shared by its biologically active analogues 5-methoxytryptophol and 6-chloromelatonin. Serotonin was only effective at a 100-fold greater concentration, while the biologically inactive melatonin metabolite 6-hydroxymelatonin was devoid of activity at any concentration used. These results suggest that methoxyindoles modulate negatively beta-adrenoceptor-induced cyclic AMP accumulation in cultured rat astroglial cells.

Animals↗
PubMed1984

Changes in plasma aldosterone levels and renin activity after bilateral superior cervical ganglionectomy in two strains of rats.

Superior cervical ganglionectomy (SCGx) of Wistar rats brought about a significant increase of plasma renin activity (PRA) 9 or 15 days later, an effect not observed 48 days after surgery. The same surgical procedure performed in Chbb Tom rats did not result in significant modification of PRA. In both strains of rats immobilization stress induced a 2.3-3.3-fold increase of PRA regardless of whether the animals had intact superior cervical ganglia. The injection of the angiotensin-converting enzyme inhibitor captopril to SCGx Wistar rats at the time of elevated PRA induced a severe hypotension, while it did not affect blood pressure in sham-operated animals. In both strains of rats SCGx resulted in depressed circulating aldosterone levels at all studied times after surgery.

Aldosterone↗
PubMed1984

Pineal and melatonin actions in reproductive endocrinology.

Daylength is the major environmental variable governing seasonal breeding, and the pineal gland is needed for this response to occur in many photosensitive species. Although dependent upon the integrity of its peripheral sympathetic innervation, the pineal has no efferent projections, and therefore it affects neuroendocrine function by humoral means. Melatonin has been proposed as the pineal hormone; its timed administration replicate the effect of daylength on seasonal breeding in several mammals, including long-day, like the hamster, and short-day breeders, like the sheep. The pineal is regulated primarily by photo-periodic information attaining the gland through a polysynaptic pathway initiated in the retinohypothalamic tract. Secondary regulators of pineal secretory activity are several steroid and polypeptide hormones. Melatonin synthesis is maximal during nighttime while during daylight it is suppressed. Melatonin acts on specific receptor sites at hypothalamic and perhaps extrahypothalamic sites to affect LHRH release. Changes in calcium fluxes, cyclic nucleotide and prostaglandin synthesis may underlie the neuroendocrine activity of melatonin at hypothalamic sites.

Animals↗
PubMed1983

Hormone effects on muscarinic cholinergic binding in bovine and rat sympathetic superior cervical ganglia.

Muscarinic receptors were assessed by [3H]-quinuclidinyl benzilate (QNB) binding in 900 xg supernatants of bovine superior cervical ganglia (SCG). At 30 degrees C half maximal binding was reached within 3 min and equilibrium within 30 min. Scatchard analysis revealed a single population of binding sites with dissociation constant (Kd) = 0.15 +/- 0.01 nM and site concentration (Bmax) = 101 +/- 4 fmoles/mg prot. Binding was specific for muscarinic drugs. Incubation of bovine SCG with different hormones (10(-7)M) indicated that LH, TRH and testosterone depressed significantly Bmax, and that prolactin decreased both Kd and Bmax of [3H] -QNB binding. Several other hormones tested (TSH, GH, FSH, LHRH, angiotensin II, bradykinin, melatonin, estradiol, thyroxine and triiodothyronine) did not affect QNB binding. Hormone effects were not due to a direct interference with radioligand binding to membrane. The injection of LH to orchidectomized rats depressed Bmax of SCG QNB binding without changing the Kd. These results suggest that muscarinic cholinergic neurotransmission in SCG may be affected by hormones.

Animals↗
PubMed1983

Inhibition by naloxone of the serotonin-induced prolactin release in free-moving rats.

The effect of the opiate antagonist naloxone on serum prolactin after treatment with serotonin, arginine vasotocin (AVT) or melatonin was studied in prepubertal and adult unanesthetized rats. Prolactin was quantified in blood samples withdrawn through an intrajugular silastic cannula from undisturbed ovariectomized adult rats. After taking a basal sample, animals were injected through the cannula with naloxone (0.8 mg/kg) and 5 min later with serotonin creatine sulphate (6.4 mg/kg), AVT (20 micrograms/kg), melatonin (4 mg/kg) or saline; new samples were taken 15 and 30 min thereafter. Injection of serotonin was followed by a 10-fold increase of prolactin levels 15 min later; this increase was drastically reduced, although not abolished, by pretreatment with naloxone. In animals injected with saline, AVT or melatonin, no significant changes in serum prolactin were observed. In a second group of experiments, 30 day-old female rats injected with serotonin creatinine sulphate (10 mg/kg, i.p.) exhibited a 6-fold increase in serum prolactin 15 min after injection; this increment was reduced but not abolished by pretreatment with naloxone (5 mg/kg, i.p.). It is postulated that the prolactin releasing effect of serotonin is mediated, at least in part, by an opioid receptor.

Animals↗
PubMed1983

Molecular mechanisms of neuroendocrine integration in the central nervous system: an approach through the study of the pineal gland and its innervating sympathetic pathway.

In the brain specialized cells known as 'neuroendocrine transducers' translate an input of neural activity into a hormonal output, e.g. oxytocin released into the blood stream. Other, more typical neurons make the reverse conversion constituting chemoreceptors which transform the hormonal 'language' into changes in their firing rate ('endocrine-neural' transduction). 'Endocrine-endocrine' transducing events occur at the level of the neurosecretory cells that translate a hormonal signal into another, different, hormone output. This article reviews the molecular aspects of several neuroendocrine integrative processes in the hypothalamus, the pineal gland and the cervical sympathetic pathway. The discussed results indicate that the pineal gland and its innervating sympathetic neurons located in the superior cervical ganglia constitute an easy-to-manipulate model system for the study of basic neuroendocrine mechanisms because: (i) receptors for various hormones exist in the mammalian pineal and sympathetic ganglia; (ii) the pattern of pineal steroid metabolism resembles that of the neuroendocrine hypothalamus; (iii) pineal estrophilic and androphilic receptors as well as the pattern of steroid metabolism are modulated by the sympathetic nerves; (iv) neuronal activity in the cervical sympathetic pathway is modified by hormone treatment at preganglionic, ganglionic and postganglionic sites.

Animals↗