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S Arancibia

Publications and source records attributed to S Arancibia.

At least 19 recordsLinked to original sources
PubMed1992

Gamma-aminobutyric acid-glutamate interaction in the control of somatostatin release from hypothalamic neurons in primary culture: in vivo corroboration.

Recent studies have provided new data on the neuroendocrine role of glutamate (the major excitatory neurotransmitter) on somatostatin release. The neuroendocrine role of gamma-aminobutyric acid (GABA) (the major inhibitory neurotransmitter) on this same secretion, is also well established. Our objective was thus to investigate whether GABA and glutamate, which have opposite neurotransmission signals, could interact in the control of hypothalamic somatostatin release. Pharmacological manipulations of the two types of receptors were performed in vitro on primary cultures of hypothalamic neurons secreting somatostatin. We found that tonic release of somatostatin was reduced by 76% in the presence of tetrodotoxin (TTX) and was regulated by endogenous secretion of glutamate and GABA. CGS 19755, a highly selective N-methyl-D-aspartate (NMDA) receptor antagonist, significantly reduced tonic somatostatin secretion whereas it was strongly increased by picrotoxin and bicuculline, two GABAA antagonists. When CGS 19755 was applied with picrotoxin, somatostatin release was the same as levels obtained in the control group with TTX. GABA reduced tonic somatostatin release (in the presence or absence of TTX), and glutamate-stimulated secretion in a dose-dependent manner. Picrotoxin stimulation of tonic somatostatin release was additive with that obtained after glutamate stimulation and was also dose-dependent. This interaction was also studied in vivo in unanesthetized rats bearing a push-pull cannula stereotaxically implanted into the median eminence. Ip injected CGS 19755 (an antagonist that can freely permeate the blood-brain barrier) completely blocked the peak secretion of somatostatin observed after ip picrotoxin administration, whereas there was no significant effect when it was injected alone. These findings corroborated our in vitro data and allow us to postulate that GABA and glutamate interact in the control of somatostatin.

Animals↗
PubMed1992

[Decrease of pineal AMPc and TOH activity in the superior cervical ganglia after ablation of submaxillary glands in rats].

In order to investigate a possible functional relationship between the submandibular salivary gland (SSG) and the central nervous system (CNS), we have extirpated the salivary organs from thirty male rats. Twenty days after ablation both the pineal glands and the cervical superior ganglions (CSG) were dissected, homogenized and frozen until AMPc and TOH were assayed respectively. We observed a significant decrease in pineal AMPc (53.9 +/- 6.2 vs 76.1 +/- 7.6% of maximum value; p less than 0.02) which seems to be linked with a significant drop in TOH activity measured at CSG level (1.5 +/- 0.6 vs 3.7 +/- 0.9 nmoles of DOPA/h/pair GCS; p less than 0.03). Our results suggest that both findings might be due to the lack of NGF normally reaching the CSG from SSG. This data reinforces the idea of a functional link between SSG and CNS via the pineal gland.

Animals↗
PubMed1991

[A non-exocrine function of the submaxillary gland].

Emphasizing on the concept of "banalization" and multifactoriality of the signal molecules of the cellular communication, the authors review data of the literature which allow to attribute to some substances synthetized by the submandibular salivary glands (SSG), mainly growth factors as EGF and NGF, an endocrine role. Because of their direct secretion in the oral cavity or their overflow into bloodstream the consequences of the deficit of these growth factors could be correlated with some oral pathologies such as aphthous lesions, puberty and pregnancy gingivitis, which endocrine etiology is often assumed, as well as autoimmune salivary pathologies. Thus, the results obtained after SSG removal furnish a support for envisaging a link between the submandibular salivary glands and the reproductive function (decrease in plasma LH level, ultrastructural changes of the Leydig cells, spontaneous abortion) and with some structures of the central nervous system such as hypothalamus (variation in hypothalamic TRH content) or pineal gland (decrease in pineal cyclic AMP content). Particularly interesting is the possibility that NGF secreted in blood by the SSG during a stress may represent the signal able to stimulate the peripheral immunity cells as well as to inform the central nervous system through a neuronal pathway via the superior cervical ganglia and the pineal gland. This brain afferent information could be associated with an increased hypothalamic NGF synthesis, also observed during stress, whose finality might be to stimulate the secretion of hypophyseal ACTH, the main hormone involved in the interrelationship between endocrine and immune response.

Animals↗
PubMed1990

Peripheral administration of picrotoxin and bicuculline stimulates in vivo somatostatin release from rat median eminence.

The gamma-Aminobutyric acid-A (GABAA) antagonist picrotoxin and bicuculline were administered to male rats to determine their effects on somatostatin (SRIF) release, measured in unanesthetized animals stereotaxically implanted with push-pull cannula in the median eminence (ME). I.p. injection (3 mg/kg) of picrotoxin (n = 5) or bicuculline (n = 6) significantly increased (35.4 +/- 10.8 vs 13.7 +/- 4.3 pg/15 min; P less than 0.03 and 38 +/- 3.5 vs 14 +/- 1.8 pg/15 min; P less than 0.001, respectively) SRIF release from the ME compared to baseline levels measured in the same animals. In contrast, with local perfusion of picrotoxin, (10(-4) to 10(-6) M) SRIF release from the ME was not affected. These data suggest a physiological endogenous inhibitory tone of GABA on SRIF release.

Animals↗
PubMed1990

Ablation of submandibular salivary glands in rats provokes a decrease in plasma luteinizing hormone levels correlated with morphological changes in Leydig cells.

This work was designed to determine whether changes in plasma and hypophyseal levels of LH are the source of the previously reported atrophy of testicular interstitial tissue following ablation of submandibular salivary glands. The plasma and hypophyseal levels of LH were assayed, and testicular sections examined by electron microscopy in rats, weighing 230-260 g, whose submandibular glands had been removed. Twenty days after sialectomy, the rats were killed, and the pituitary glands removed, homogenized and frozen until used in LH-RIA like the blood samples. Testes were removed and fixed in osmic acid. There was a significant decrease in plasma LH levels in operated animals when compared with sham-operated controls (47.28 +/- 7 ng/ml versus 70.42 +/- 8; p less than 0.02), but the hypophyseal LH content was not significantly modified. Electron microscopy mainly showed important changes in the morphology of the Leydig cells, with a distinct reduction in the number of mitochondria and elements of the smooth endoplasmic reticulum. These findings suggest a physiological involvement of submandibular glands in a possible endocrinological link with the gonadotropic axis.

Animals↗
PubMed1990

["Push-pull" perfusion technic, a new approach applied to the study of transdentinal fluid].

The flux through the dentin tubuli is at the origin of the hydrodynamic theory of tooth sensitivity. After a review of the various in vivo techniques reported in the literature, this study describes an original method of dentin perfusion--so called "push-pull" and specific to this topic. With this technique, the authors have demonstrated the kinetics of this flux, as well as the effect of some factors (age, colchicine, ouabain), on transdentinal fluid exchanges. The analysis of all these results suggests that a combination of active and passive movements could be at the origin of this flux, the temporary inhibition of which could present major advantages in current Periodontics practice.

Age Factors↗
PubMed1989

Physiological evidence for alpha 1-adrenergic facilitatory control of the cold-induced TRH release in the rat, obtained by push-pull cannulation of the median eminence.

The alpha-adrenergic antagonists phentolamine and prazosin were administered to male rats to explore their effects on cold-induced TRH release, measured by a chronic push-pull cannula stereotaxically implanted in the median eminence (ME). Phentolamine was given either i.p. (24 or 40 mg/kg), or locally (10(-5) M) in the ME, whereas prazosin was only applied locally (10(-5) M). Phentolamine significantly decreased the cold response (5 +/- 1 pg/15 min vs 21 +/- 5 pg/15 min; P less than 0.02), whatever the administration mode. Moreover, the blocking effect of prazosin directly perfused into the ME (11 +/- 3 pg/15 min vs 26 +/- 9 pg/15 min; P less than 0.05), indicates the specific involvement of alpha 1-adrenergic receptors in the cold-induced TRH response, and points to the ME as a possible site of facilitatory adrenergic control.

Animals↗
PubMed1989

Increases in concentrations of somatostatin- and insulin-like immunoreactivities in submandibular salivary gland of diabetic rats: effect of insulin treatment.

To investigate whether systemic insulin levels can influence somatostatin-like immunoreactivity and insulin-like immunoreactivity concentrations in the rat submandibular salivary glands, we measured the concentrations of the two peptides in an experimental group rendered diabetic by streptozotocin administration. The diabetic group showed a low plasma level of insulin compared with the control group: 0.5 +/- 0.1 vs 3.5 +/- 0.8 micrograms/l, (P less than 0.01). Concomitantly, they exhibited clear glucosuria and a blood glucose level which was four times higher than in normal animals: 35.5 +/- 1.4 vs 8.8 +/- 0.8 mmol/l, (P less than 0.001). The two peptide concentrations in the submandibular glands of diabetic rats showed an increase compared with controls: 42.9 +/- 4.7 protein vs 24.7 +/- 3.1 pg/mg protein (P less than 0.001) and 34.9 +/- 4.9 protein vs 18.4 +/- 4.0 pg/mg protein (P less than 0.01), for insulin-like immunoreactivity concentration and somatostatin-like immunoreactivity concentration, respectively. Chronic insulin treatment of diabetic rats reversed the increase in somatostatin, but had no effect on the increase in insulin-like immunoreactivity concentration. A negative correlation (r = 0.24, P less than 0.05) was found between the plasma insulin level and the somatostatin concentration of the submandibular glands. Our results suggest that the submandibular glands of rats may participate in the peripheral regulation of glucose homeostasis.

Animals↗
PubMed1988

[Changes induced by ouabain and colchicine in the transdentinal flow estimated in vivo by perfusion: the "push-pull" of the incisors of rats].

The active or passive mechanisms regulating the various movements of dentinal fluid have not yet been sufficiently studied. For this reason different "in vivo" factors that may modulate the kinetics of transdentinal flow were investigated. After systemic administration of a radiotracer in rats, the kinetics were examined with a push-pull perfusion device fixed to the incisor dentin. The drugs chosen, i.e. ouabain and colchicine, were for their respective effects on microtubules and on the ATPase-dependent Na+ K+ pump, since these two factors are involved in the transport process. Anesthetized animals were prepared to allow intravenous injection of iodine 125 (0,5 to 0,7 mCi), carotid sampling, and perfusion of upper incisors. Ouabain induced a very significant decrease in transdentinal flow, which was particularly evident in younger animals (2,81 x 10(-2) % vs 0,04 x 10(-2)%, p less than 0,05). However, colchicine produced two different kinds of results : at low doses (3,5 to 5 mg/100 g) the pulsatile pattern of the curves was partially inhibited, whereas, at higher doses (6 to 7 mg/100 g), the transdentinal flow of radioactivity increased. These results suggest that a combination of active and passive transport may be involved in the various movements of this fluid.

Animals↗
PubMed1988

Decrease of hypothalamic TRH levels but not plasmatic TSH levels after ablation of submandibular salivary glands in the rat.

Indirect relationships are thought to exist between submandibular salivary glands (SSG) and the central nervous system (CNS) via superior cervical ganglia (SCG). To study this topic, the concentrations of thyrotropin releasing hormone (THR) and somatostatin (SRIF) were measured in both whole and specific areas of the hypothalamus, as well as plasmatic thyrotropin stimulating hormone (TSH) levels following ablation of SSG. Twenty, forty and fifty days after ablation of SSG, groups of operated and sham-operated animals weighing 230-260 g at the beginning of experimentation, were killed by cervical dislocation. Plasma was taken, frozen and stored for TSH-radioimmunoassay (RIA) and the hypothalami were removed and homogenized in either 0.1 N HCl (for TRH-RIA) or 0.2 N acetic acid (for SRIF-RIA). Twenty days after ablation of SSG in another group, TRH concentrations were measured in both the median eminence (ME) and the paraventricular nucleus (PVN), dissected by the micropunch technique. The results show that twenty days after SSG ablation, the hypothalamic TRH concentrations was significantly lower in operated than in sham-operated animals (295.2 +/- 24.8 vs 226 +/- 11.15 pg/mg hypothalamus respectively p less than 0.01, n = 9). No differences were observed at later intervals. This finding seems to be specific for this peptide since the SRIF level was not modified twenty days after SSG removal. Among the discrete hypothalamic areas examined, only the ME exhibited a significant decrease in TRH content (25.43 +/- 3.02 ng/mg prot. VS. 41.24 +/- 1.33 ng/mg prot., respectively). Despite these results on TRH levels, no modifications in plasmatic TSH levels were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Somatostatin-immunoreactive concentrations in human saliva and in the submandibular salivary glands of the rat. Possible sexual dependence in the human.

Many biologically active polypeptides have been detected either in the submandibular salivary glands (SSG) of the rat, and in the saliva of rats and humans. The present work has investigated the case of somatostatin (SRIF), since salivary data concerning the presence of this peptide are scarce and contradictory. In a group of healthy volunteers, SRIF-immunoreactivity (SRIF-IR) was tested in samples of mixed saliva. Not all the subjects revealed presence of SRIF-IR in saliva. For men, 5 out of 9 were positive (x = 26.40 +/- 10.03 pg/ml), whereas for women only one out of 10 was positive (x = 96.40 pg/ml). SRIF-IR was also determined in male rat submandibular glands from control animals (26.1 +/- 6.3 pg/mg protein, n = 18) and from animals injected one hour before with an alpha 1-adrenergic secretagogue, phenylephrine (27.9 +/- 7.1 pg/mg protein, n = 6). The results show that SRIF-IR is not constantly present in human saliva obtained from a young population, and that its presence apparently seems to differ between the sexes. On the other hand, the fact that SRIF-IR, unlike other peptides, is not modified when the animals are injected with phenylephrine, may simply indicate that the control mechanism of SRIF-IR release is not the same as that affecting other salivary peptides. Further studies must be carried out in order to elucidate the origin and role of salivary SRIF-IR.

Adolescent↗
PubMed1987

["Push-pull" perfusion technic in neuroendocrinology].

In this article the author reviews the different models of push-pull cannula device used in neuroendocrinology, mainly those applied to the study of neurohormones release from median eminence (ME). At present, three technical details might explain some disagreements resulting from application of push-pull perfusion (PPP) in neuroendocrinology, concerning for instance, the SRIF release: firstly, the tissue damage connected with the diameter of the cannulas utilized (guide and perfusion), secondly, the perfusion flow which can vary from 15 to 40 microliter/min according to the authors, and finally, the means of implanting the cannula in the ME (between 8 days and 1 hour before perfusion). The author compares the values of SRIF, TRH and CRF releases measured by portal cannula with those obtained by PPP. It would seem that the application of a physiological stimulus triggers a response measured in the perfusate whose amplitude as compared to basal levels, is more important than the amplitude measured in portal blood. In conclusion, in despite of its limits--reproductiveness and yield--, at the present time PPP may be considered one of the major methodological tools affording the physiologist optimum conditions for in vivo studies.

Animals↗
PubMed1987

[Secretion of TRH in the third cerebral ventricle during acute cold exposure in the unanesthetized rat. Effect of alpha-adrenergic drugs].

The concentrations of TRH in the cerebrospinal fluid (CSF) of the 3rd ventricle were measured with push-pull cannulae in 12 conscious rats. In the basal state the level of TRH in 15 min perfusion samples (210 microliters) were low (2.69 +/- 0.05 pg) and mostly undetectable with the RIA available. However, 70 to 80 min after exposure of the rats to cold (4 degrees C) a short lived but significant rise of TRH was measured in all animals. Post cold peaks amounted to 5.15 +/- 0.5 pg/15 min (p less than 0.001 vs baseline levels). This cold response to CSF TRH was influenced neither by pretreatment of rats with the alpha-adrenergic blocker phentolamine, administered i.p. (40 mg/kg) or i. c. v. (10(-5) M) 1 h before cold exposure, nor by i. c. v. infusion of the alpha 1-adrenergic blocker prazosin (10(-5) M). In rats receiving the blockers the post-cold TRH peaks were 6.76 +/- 1.61 pg/15 min and 5.70 +/- 0.70 pg/15 min, respectively. The possible origin of CSF TRH and the resistance of its cold stimulation to alpha-adrenergic blockers, compared to TRH released into the median eminence are discussed.

Animals↗
PubMed1987

[Evaluation of an in vivo perfusion technic for the dental pulp in rats as validated by demonstration of the release of prostaglandins].

Many different biologically active substances contribute to the metabolism of dental pulp. Until now, release of these substances has been evaluated only by in vitro studies. The aim of this study was to establish a technique of perfusion allowing the evaluation in vivo of the secreting activity of dental pulp. In order to validate this technique, the in vivo release of prostaglandins, substances which seem to play a key role in pulpal metabolism was measured. The "push-pull" perfusion technique was used, whereby a physiological medium was made to bath the pulpal surface by aspiration. Pulp was exposed by opening an upper incisor in an anaesthetized rat. The perfusion was kept constant by means of a device composed of cannula, catheters, and micropumps which produced a flow followed by an aspiration of the liquid. Every ten minute fraction was analysed by high performance liquid chromatography. Ten minutes after the beginning of perfusion, the results showed a kinetic for PGE2 and PGF2 alpha release, characterized by a base level of 7.4 +/- 6.7 and 28.6 +/- 12.0 pg/min respectively. These were interrupted by a very high peak as compared to base level (19 times higher for PGE2 and 6.6 times for PGF2 alpha), occurring fifty minutes after trepanation. This experiment is the first attempt made in vivo and in situ, to measure biologically active substances of pulpal origin.

Animals↗
PubMed1986

Effects of morphine on cold-induced TRH release from the median eminence of unanesthetized rats.

The effect of morphine perfusion into the median eminence on cold-induced TRH secretion was studied in unanesthetized rats by push-pull cannulation. Perfusion with 10(-6)M morphine blocked the cold-induced TRH peak occurring about 40 min after the transfer of rats from 24 degrees C to 4 degrees C. This inhibition by morphine was blunted by concomitant administration of naloxone (10(-6)M or 10(-5)M), but naloxone alone had no effect on either basal or cold-induced TRH release. We conclude that specific opiate receptors may be located on TRH nerve endings in the ME, and that endogenous opiates may not have any physiological role in the cold-induced TRH response, at least during the two hours that follow cold exposure.

Animals↗
PubMed1986

Probable extrapituitary source of the immunoreactive prolactin measured in the cerebrospinal fluid of unanesthetized rats by push-pull cannulation of the 3rd ventricle.

The dynamic pattern of the immunoreactive prolactin (PRL) concentrations in the cerebrospinal fluid (CSF) of the 3rd ventricle was explored by push-pull cannulation during either stimulation or blocking of PRL production in the plasma, which itself was sampled by chronic cannulation of the carotid. Some of the results were compared to the PRL concentrations in CSF samples obtained by 3rd-ventricle puncture. Ether stress, which induced a 4- to 6-fold rise in plasma PRL, altered neither the pulsatile circhoral pattern of PRL in the CSF nor the mean level and amplitude of its pulses. However, the sustained intense hyperprolactinemia induced by haloperidol increased the mean PRL level in the CSF and possibly its pulse rate. Surprisingly, hypophysectomy, which suppressed production of PRL in the plasma, did not alter its baseline level or cycling pattern in the CSF. The possibility that tuberal adenohypophysial cells and/or CNS prolactinergic neurons supply the CSF with PRL is discussed.

Animals↗
PubMed1986

Effect of submandibular salivary gland removal on body weight, plasmatic testosterone levels, testicular weight and spermatogenesis in rats.

In this work we report the effect of the removal of submandibular salivary glands (S.S.G.) on plasmatic testosterone levels and other aspects of testicular function and on body weight in rats. Our results were obtained with 72 male rats weighing 230-260 g whose S.S.G. were removed. At only twenty days after removal a slight but significant decrease (p less than 0.05) of testicular absolute weight (3.431 +/- 75 mg vs 3.612 +/- 53 mg) was detected. This decrease was probably due to atrophy of interstitial tissue, as revealed by histological examination. In contrast, neither plasmatic testosterone (T) levels nor spermatogenesis (S.P.G.) were altered. The effect on testicular weight at twenty days was not closely associated with the effect on body weight. Changes in this latter parameter were observed twenty days after extirpation of S.M.G. (107 +/- 5.5 vs 124 +/- 4.3 g; p less than 0.02) and up until forty days (175.6 +/- 4.1 g vs 202.8 +/- 5.5; p less than 0.05) after S.S.G. removal. Difference in gain of body weight is not influenced by nutritional lack, as shown by the fact that nutritional absorption is not modified in the operated animals controlled in wire bottom cages. These data suggest that S.S.G. right play a trophic regulatory role, separately, on testes and body without the mediation of T. The direct involvement of biological peptides contained in S.S.G. is discussed.

Animals↗