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Biomedical subjects

A Arce

Publications and source records attributed to A Arce.

83 records · Page 5Linked to original sources
PubMedDate not supplied

Circadian rhythms in adenohypophysial hormone levels and hypothalamic monoamine turnover in mycobacterial-adjuvant-injected rats.

The effect of Freund's adjuvant injection on 24-hour variation in circulating ACTH, prolactin, growth hormone (GH) and thyroid-stimulating hormone (TSH) levels, and of hypothalamic norepinephrine (NE) content and dopamine (DA) and serotonin (5HT) turnover was examined in adult rats. In control rats, serum ACTH and prolactin exhibited peak values at the light-dark transition while the maximum in TSH was found in the late afternoon. GH levels did not vary on a 24-hour basis. In Freund's-adjuvant-injected rats, 24-hour variations in TSH levels became blunted while 24-hour variations in prolactin and ACTH persisted. Freund's adjuvant treatment augmented serum ACTH and prolactin levels, and decreased GH and TSH levels. Hypothalamic NE content, and turnover of DA and 5HT varied on a 24-hour basis in rats receiving adjuvant's vehicle. The NE content of the anterior, medial and posterior hypothalamus peaked at 04.00 h, while that of the median eminence attained its maximum at 16.00-20.00 h. Maxima in hypothalamic DA and 5HT turnover occurred at 04.00 h regardless of the region examined. In Freund's-adjuvant-injected rats, reduced amplitude of daily variations of NE content in the median eminence and anterior and medial hypothalamus, as well as a phase advance in the 24-hour rhythm of the posterior hypothalamic NE content were seen. Mycobacterial adjuvant injection also reduced the amplitude of circadian rhythm in hypothalamic 5HT turnover, shifted the maximum in median eminence DA turnover towards light-dark transition, and decreased the amplitude of DA turnover rhythm in the anterior, medial and posterior hypothalamus. Administration of the immunosuppressant drug cyclosporine restored the augmented ACTH and prolactin levels and the depressed GH and TSH levels found in Freund's-adjuvant-injected rats. Cyclosporine was also effective to restore 24-hour rhythmicity of serum ACTH and TSH, but not of prolactin levels. Immunosuppression restored rhythmicity of NE content and of DA and 5HT turnover in anterior, medial and posterior hypothalamic regions. Cyclosporine did not modify the effect of Freund's adjuvant on median eminence but in was able to counteract the changes in the DA and 5HT turnover in the median eminence found after immunization. The results are in accord with a significant effect of immune-mediated inflammatory response at an early phase after Freund's adjuvant injection on ACTH, GH, prolactin and TSH release mechanisms, which was partially sensitive to immunosuppression induced by cyclosporine.

Animals↗
PubMedDate not supplied

Acute and chronic effects of superior cervical ganglionectomy on in vitro mitogenic responses of lymphocytes from submaxillary lymph nodes of pituitary-grafted rats.

Male rats were grafted an anterior pituitary within breast muscles or received a sham operation on day 5 of life. At the 60th day of life, the sympathetic denervation of rat submaxillary lymph nodes was achieved by a bilateral sympathetic superior cervical ganglionectomy (SCGx; at 15.00 h). Rats were killed either 18 h later (acute SCGx) or after 12 days (chronic SCGx) to measure lipopolysaccharide (LPS)- and concanavalin A (ConA)-induced cell proliferation in submaxillary lymph nodes, submaxillary lymph node cellularity and serum prolactin levels. In control rats, acute SCGx significantly augmented LPS or ConA activity on lymph cells while chronic SCGx had no effect. In pituitary-grafted rats, acute SCGx depressed the mitogenic effect of LPS or ConA whereas chronic SCGx augmented it. A global inhibitory effect of surgical stress on submaxillary lymph node cellularity was found in rats subjected to SCGx or its sham operation 18 h earlier. Serum prolactin levels increased significantly in pituitary-grafted rats, particularly in those subjected to chronic SCGx. In pituitary-grafted rats, a significant effect of acute SCGx was apparent, with serum prolactin levels augmenting about twice in sham-SCGx rats, and to a significantly less extent in acute SCGx rats. The results provide further evidence of the immunomodulatory role of local sympathetic nerves in submaxillary lymph nodes.

Animals↗
PubMedDate not supplied

Twenty-four hour rhythms of hypothalamic corticotropin-releasing hormone, thyrotropin-releasing hormone, growth hormone-releasing hormone and somatostatin in rats injected with Freund's adjuvant.

The effect of Freund's adjuvant injection on 24-hour variation of hypothalamic corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), GH-releasing hormone (GRH) and somatostatin levels was examined in adult rats kept under light between 0800 and 2000 h daily. Groups of rats receiving Freund's complete adjuvant or its vehicle 3 days before sacrifice were killed at six different time intervals throughout a 24-hour cycle. In the median eminence, adjuvant vehicle-injected rats exhibited significant 24-hour variations for the four hormones examined, with maxima at noon. These 24-hour rhythms were inhibited or suppressed by Freund's adjuvant injection. In the anterior hypothalamus of adjuvant vehicle-treated rats, CRH content peaked at 1600 h, while two peaks were found for TRH and GRH levels, i.e., at 2400-0400 h and 1600 h. Freund's adjuvant injection suppressed 24-hour rhythm of anterior hypothalamic CRH, TRH and GRH content and uncovered a peak in anterior hypothalamic somatostatin levels at 0400 h. In the medial hypothalamus of adjuvant vehicle-treated rats, significant 24-hour variations were detectable for TRH (peaks at 1600 and 2400 h) and somatostatin (peak at 2400 h) which disappeared after Freund's adjuvant injection. In the posterior hypothalamus of adjuvant vehicle-treated rats, two peaks were apparent for CRH, TRH and somatostatin levels, i.e. at 1600 h and 2400-0400 h, this hormonal profile remaining unmodified after Freund's adjuvant administration. The administration of the immunosuppressant drug cyclosporine (5 mg/kg, 5 days) impaired the depressing effect of Freund's adjuvant injection on CRH, TRH and somatostatin content in median eminence, but not that on GRH. In the anterior hypothalamus, cyclosporine generally prevented the effect of immunization on hormone levels an revealed a second maximum in TRH at 0400 h. Cyclosporine also restored 24-hour variations in TRH and somatostatin levels of medial hypothalamus of Freund's adjuvant-injected rats but was unable to modify them in the posterior hypothalamus. The results further support the existence of a significant effect of immune-mediated inflammatory response at an early phase after Freund's adjuvant injection on hypothalamic levels which was partially sensitive to immunosuppression by cyclosporine.

Animals↗
PubMedDate not supplied

Age-dependent effect of pituitary transplants on immune responses in rat submaxillary lymph nodes: modulatory effect of the autonomic nervous system.

An anterior pituitary was grafted into the breast muscles of male rats on day 5, or under the kidney capsule on day 30 or 60 of life. At the 70th day of life (rats operated at the 5th or 30th day) or at the 100th day of life (rats operated at the 60th day), rats were injected subcutaneously with Freund's complete adjuvant, being killed 2 days later. Rats pituitary-grafted at the 30th day showed a greater hyperprolactinemia than rats grafted at the 5th or 60th day. Submaxillary lymph node natural killer (NK) activity decreased in neonatally pituitary-grafted rats and increased in rats grafted at the 30th or 60th day of life, while lymph node cellularity decreased in rats grafted at the 30th or 60th day. In the case of lipopolysaccharide (LPS)-and concanavalin A (Con A)-induced cell proliferation in lymph nodes, the only significant factor detected was age of transplantation, the effect being less evident in older animals. To examine whether the autonomic denervation of submaxillary lymph nodes affected immune responses in pituitary-grafted rats, animals were subjected to a unilateral superior cervical ganglionectomy (Gx) and/or a parasympathetic decentralization (Dc; by chorda tympani section), 10 days before immunization with Freund's adjuvant. A unilateral Gx blunted the stimulation of lymph node NK activity in rats receiving a pituitary transplant at the 30th or 60th day, but not at the 5th day. Only in sympathetically denervated lymph nodes a significant effect of pituitary transplants on LPS mitogenic effect was found, with significantly less effect of LPS in rats pituitary-grafted at the 5th or 30th day of life. Regarding Con A, a unilateral Gx or unilateral Gx plus Dc uncovered a significant depressive effect of pituitary transplants with a significantly smaller Con A mitogenic effect at each studied age in ipsilaterally Gx lymph nodes, and at 30 and 60 days of age in ipsilaterally Gx plus Dc lymph nodes. Pituitary grafts augmented Con A- induced proliferation in submaxillary lymph nodes at the 5th day of life while they decreased it at the 60th day of life. Pituitary transplants augmented cellularity at the sympathetically denervated lymph nodes and decreased it at the contralateral sham-operated side. Pituitary transplants also diminished lymph node cellularity at the Dc side, the effect being significant in rats transplanted at the 30th day of life. The results are compatible with age-dependent, inhibitory as well as promoting activities of hyperprolactinemia on immune responses in submaxillary lymph nodes, depending in part on intact autonomic nerves.

Age Factors↗
PubMedDate not supplied

Age-dependent effect of pituitary transplants on immune responses in rat spleen: modulatory effect of cyclosporine.

Male rats were grafted an anterior pituitary within breast muscles on day 5 or under the kidney capsule on day 30 or 60 of life. On the 70th day of life (rats operated on the 5th or 30th day) or on the 100th day of life (rats operated on the 60th day), rats were injected subcutaneously with Freund's complete adjuvant, being killed 2 days later. Rats that had received a pituitary graft on the 30th day showed a greater degree of hyper-prolactinemia than rats grafted on the 5th or 60th day. Analyzed as main factors in a factorial analysis of variance (ANOVA), pituitary transplants augmented splenic natural killer (NK) activity and lipopolysaccharide (LPS)- and concanavalin A (Con A)-induced cell proliferation, and decreased splenic cell number. As indicated by significant interactions between treatment and age of transplantation in a factorial ANOVA, splenic NK activity augmented in rats grafted on the 30th day of life, while LPS and Con A splenic cell proliferation augmented in rats grafted neonatally. Spleen cellularity decreased after pituitary transplants in 30- and 60-day-old rats. In a second study, the effect of cyclosporine on spleen immune responses was tested by administering cyclosporine (5 mg/kg) or vehicle to rats grafted as in experiment 1 for 5 days before sacrifice. Cyclosporine decreased splenic NK activity and LPS- and Con A-induced cell proliferation regardless of the presence of a pituitary graft. In rats grafted on the 30th day of life, cyclosporine reversed the effect of pituitary grafts on splenic NK activity, and ectopic pituitary augmenting NK activity in vehicle-treated rats while decreasing it in cyclosporine-injected rats. Cyclosporine reversed the inhibitory effect of pituitary transplants on spleen cell number. The high circulating prolactin levels found in rats with pituitary grafts were decreased by cyclosporine administration. The results are compatible with age-dependent promoting and inhibitory effects of hyperprolactinemia on the immune responses of the spleen, which were antagonized by cyclosporine immunosuppression.

Aging↗
PubMedDate not supplied

Effect of cyclosporine on immune responses in submaxillary lymph nodes of pituitary-grafted rats.

This work was undertaken to analyze the interrelationships between prolactin and cyclosporine in affecting immune responsiveness in submaxillary lymph nodes. Male rats received an anterior pituitary graft within breast muscles on day 5, or under the kidney capsule, on day 30 or 60 of life. On day 70 (rats operated on day 5 or 30) or on day 100 (rats operated on day 60) animals were injected with Freund's complete adjuvant and cyclosporine (5 mg/kg for 5 days), and were killed 2 days after immunization. Natural killer (NK) activity in submaxillary lymph node decreased in neonatally pituitary-grafted rats and increased in rats grafted on day 30 or 60, as did lymph node cellularity. Lipopolysaccharide (LPS)- and concanavalin A (ConA)-induced proliferation diminished in lymph nodes of rats grafted on day 30 or 60, respectively. Cyclosporine treatment diminished lymph node cell number and NK activity and increased the proliferative response to ConA. Cyclosporine depressive effect on lymph node cellularity was counteracted by the presence of a pituitary graft, as were the inhibition of NK activity and the stimulatory effect on ConA-induced cell proliferation. In pituitary-grafted rats, cyclosporine decreased submaxillary lymph node LPS-induced proliferation. Cyclosporine decreased the high circulating prolactin levels found in pituitary-grafted rats. The results are compatible with age-dependent, inhibitory and promoting activities of hyperprolactinemia on immune responses in lymph nodes, affected in a complex antagonistic and synergistic way by cyclosporine immunosuppression.

Aging↗
PubMedDate not supplied

Piribedil could modify dopamine turnover in cochleas under noise stimulation.

Dopamine (DA) is one of the putative neurotransmitters of the lateral efferent olivocochlear fibers. The cochlear DA content after noise exposure was analyzed using high-performance liquid chromatography coupled with electrochemical detection. Animals were exposed for 1 h to white noise at 70, 90 or 110 dB SPL or were kept in conditions of silence. Half of the animals were pretreated with piribedil, a D2 agonist, and the other half served as controls. In control (untreated) animals, noise stimulation resulted in a progressive decrease of cochlear DA concentration. This decrease was scarcely detected when animals were pretreated with piribedil. Present findings indicate that piribedil modifies cochlear DA turnover under noise stimulation.

Acoustic Stimulation↗
PubMedDate not supplied

Partitioning of 1,4-benzodiazepines into natural membranes.

The partition coefficients of several 1,4-benzodiazepin-2-ones (BZDs) were determined in a synaptosomal membrane-buffer system (Pm/b) by a two-component model analysis of the experimental data and the following values were obtained: flunitrazepam (FNTZ) = 32.2 +/- 1.5; diazepam (DZ) = 79 +/- 9; clonazepam (CNZ) = 30 +/- 4; nitrazepam (NTZ) = 38 +/- 2 and chlorodiazepoxide (CDZX) = 15.7 +/- 0.6. Correlations between these Pm/b and other chemical properties were performed by a principal component analysis. Hydrophobicity of BZDs, measured as the partition coefficients in different solvent systems, could be correlated with the presence of a methyl group at position 1 of the seven-member ring of the BZD molecule. The values of the partition coefficients of benzodiazepine in the synaptosomal membrane-buffer system were one order of magnitude lower than those obtained in an octanol-water or in ethyl acetate-water systems. The complexity of the membrane, unlike the isotropy of a pure solvent phase, provides a wide spectrum of types of interactions which, in turn, can be modulated in a dynamic manner by local or generalized changes in the lipid phase state. In that sense, the present values of Pm/b should be interpreted as an average tendency of BZDs to establish non-specific interactions with the molecules present in the different phases within biological membranes. Conversely, these Pm/b values reflect a consequence of the difference in complexity between natural membranes and the systems currently used as membrane models for drug partitioning.

Animals↗
PubMedDate not supplied

[Septo-optic dysplasia].

INTRODUCTION: Septo optic syndrome, described by De Morsier in 1956, consists in the hypoplasia of one or both optic nerves, mid line brain malformations and hypothalamohypophysial dysfunction, which is inconstant. It is an infrequent, but treatable, cause of hepatic and neurological damage, and it is important to obtain an early diagnosis and to begin hormone replacement therapy. CASE REPORT: We report the clinical case of a female baby who was diagnosed early on as suffering from septo?optic dysplasia, after discovery of the existence of cholestatic jaundice. In our case the three components of the syndrome were present: hypothalamohypophysial dysfunction, bilateral hypoplasia of the optic nerves and brain malformations with dysplasia of the transparent septum. All this gives rise to complex clinical features and the predominance of hypernatraemic dehydration secondary to insipid diabetes, nystagmus and serious psychomotor retardation. Our patient died, as in other cases reported in the literature, from an episode of sudden death. DISCUSSION: Despite the importance of an early diagnosis of this disorder, it is usually late. Most children who present hypopituitarism traits in the neonatal period are not diagnosed at that time, with the subsequent risk of death or brain damage. Some clinical findings, which appear early on and can provide clues which aid us to reach a diagnosis, are the appearance of episodes of hypoglycaemia in the neonatal period, the existence of micropenis and cryptorchidism with hypoplasic testes, jaundice or the appearance of clinical manifestations of insipid diabetes. Later on nystagmus and neurological symptoms may appear. The final diagnosis is performed through the use of neuroimaging techniques (CT or MRI) and hormonal studies.

Fatal Outcome↗
PubMedDate not supplied

[Treatment of hepatorenal syndrome with dopamine and bromocriptine].

Two cirrhotic patients with hepatorenal syndrome were treated with Dopamine hydrochloride and Bromocriptine, a Dopamine agonist. Dopamine hydrochloride was given at a dosis of 0.30 to 0.90 mg/min. and Bromocriptine 15 mg/day. Although a transient raise of urinary output was observed in one patient, both patients died six to ten days later with an urinary output of less than 100 ml/day. Dopamine and Bromocriptine combined are of poor therapeutic value in hepatorenal syndrome.

Adult↗