RESUMEN

OBJECTIVES: To investigate the outcome of dogs with central nervous system lymphoma. MATERIALS AND METHODS: A multi-center, retrospective, observational study was conducted by reviewing medical records of 18 cases of central nervous system lymphoma from seven institutions. RESULTS: Diagnosis of lymphoma was made through cerebrospinal fluid analysis, histopathology, flow cytometry of the cerebrospinal fluid, and cytology of cerebrospinal fluid, lymph node or spleen with correlated imaging. A total of 15 of 18 dogs received specific treatment other than prednisone. Three dogs underwent chemotherapy and radiation therapy after surgical decompression, five dogs underwent chemotherapy, two dogs underwent radiation therapy after surgical decompression, three dogs underwent chemotherapy after surgical decompression and two dogs underwent radiation therapy and chemotherapy. Only one dog received prednisone, and two dogs did not receive any treatment. Overall, the median survival time was 171 days (range 1 to 1942 days). CLINICAL SIGNIFICANCE: Dogs receiving any type of treatment for central nervous system lymphoma lived longer than cases described in previous historical reports. Further studies are needed to elucidate the importance of specific treatment modalities.

Asunto(s)

RESUMEN

Recent data suggest that the presence of psychotic symptoms in patients suffering from posttraumatic stress disorder (PTSD) may represent an underrecognized and unique subtype of PTSD. Among combat veterans with PTSD, 30% to 40% report auditory or visual hallucinations and/or delusions. The presence of psychotic symptoms in PTSD is associated with a more severe level of psychopathology, similar to that of chronic schizophrenia. In this review, the differential diagnosis of psychotic symptoms in PTSD is discussed, including possible comorbid schizophrenia, psychotic depression, substance-induced psychosis, and personality disorder. A recent biologic study supporting the existence of a unique subtype of PTSD with psychotic features is also addressed, as are the similarities between PTSD with psychotic features and psychotic depression disorder. Finally, data on the treatment implications of psychotic symptoms in PTSD are presented. The intriguing recent findings on psychotic symptoms in PTSD need further investigation in noncombat-related PTSD populations before findings can be generalized to all individuals with PTSD.

RESUMEN

Multiple neurochemical estimates were used to examine peripheral corticosterone (CORT) effects in dopaminergic terminal regions. Acute CORT administration, which elevated plasma CORT (5 h), slightly decreased dihydroxyphenylacetic acid (DOPAC) to dopamine (DA) ratios in the striatum but not in other regions examined. Two weeks of adrenalectomy (ADX) increased both medial prefrontal cortex DOPAC/DA and homovanillic acid (HVA)/DA and striatal HVA/DA. A reciprocal pattern of changes was observed with CORT replacement in ADX animals. In contrast, CORT replacement in ADX animals did not significantly influence tyrosine hydroxylase content, basal dihydroxyphenylalanine (DOPA) accumulation after NSD 1015 treatment or the decline in DA after alpha-methyl-para-tyrosine, suggesting that neither DA neuronal activity nor release are altered by CORT. Moreover, neither gamma-hydroxybutyric acid lactone-induced increases in DOPA accumulation or stress-induced increases in DA utilization were influenced by CORT replacement, indicating that neither autoreceptor regulation of DA synthesis nor acute stress regulation of DA utilization are changed by CORT. The findings are most consistent with direct inhibition of basal DA metabolism in the medial prefrontal cortex and striatum. The possible physiological and behavioral significance of this inhibition is being further explored.

Asunto(s)

RESUMEN

Differences in the behavioral responses of Lewis and Fischer (F344) inbred rat strains to stress and psychoactive drugs have been related to differences in the expression of various regulatory proteins in regions containing mesolimbic dopamine (DA) neurons. The present study compared basal and stimulated neurochemical estimates of DA utilization and synthesis in mesocortical, mesolimbic and nigrostriatal DA terminal regions of these two strains. In unstressed control animals, the Lewis strain had lower DA concentrations in the dorsal striatum (ST; 80.3% of F344) and lower basal dihydroxyphenylalanine (DOPA) accumulation after m-hydroxybenzylhydrazine (NSD 1015) treatment in the medial prefrontal cortex (mPfx; 75.3% of F344). Similar differences were observed in vehicle-injected animals. No strain differences in basal neurochemistry were apparent in the nucleus accumbens shell (NAs) or core (NAc). In response to restraint stress, dihydroxyphenylacetic acid (DOPAC) to DA ratios in the mPfx, NAs and ST increased in the F344 but not the Lewis strain. However, restraint stress did not significantly increase DOPA accumulation in the F344 strain. This latter finding was not due to a deficit in synthesis capacity, as gamma-hydroxybutyric acid lactone (GBL) increased DOPA accumulation significantly more in F344 than Lewis animals. Finally, haloperidol increased DA utilization similarly in the two strains. Together these findings suggest that the inbred, behaviorally divergent F344 and Lewis rats have selective differences in mesocortical, nigrostriatal and mesolimbic DA neuronal regulation.

Asunto(s)

RESUMEN

When separated from groups, squirrel monkeys respond with significant increases in plasma cortisol and adrenocorticotropic hormone (ACTH). While cortisol remains elevated above pre-separation levels, significant reductions occur in ACTH. Monkeys that respond with greater increases in cortisol subsequently exhibit greater reductions in ACTH, which suggests that reductions in ACTH are mediated by corticosteroid feedback. Monkeys that respond with greater increases in cortisol also tend to exhibit greater cerebrospinal fluid levels of the dopamine metabolite HVA, but not the norepinephrine metabolite MHPG, or corticotropin-releasing factor (CRF). Attenuation of corticosteroid feedback with metyrapone results in significant increases in circulating ACTH, and in older monkeys increases plasma HVA. Similar findings in humans have been reported in clinical studies of hypercortisolism and major depression.

Asunto(s)

Asunto(s)

RESUMEN

The ability of sodium butyrate and dexamethasone to promote adrenergic differentiation in PC12 cells was examined using the gene encoding the epinephrine biosynthetic enzyme, phenylethanolamine N-methyltransferase (PNMT), as a marker. Sodium butyrate and dexamethasone independently stimulated expression of PNMT mRNA in PC12 cells, and the combined action of these drugs led to synergistic activation of the PNMT gene. Despite the induction of the PNMT gene, epinephrine is not produced in these cells, in part due to the absence of a corresponding induction in PNMT enzymatic activity. Another contributing factor appears to be a reduction in the precursor catecholamines, norepinephrine and dopamine, in the presence of sodium butyrate. Thus, while sodium butyrate and dexamethasone can induce PNMT gene expression, treatment of PC12 cells with these drugs appears insufficient for full acquisition of the adrenergic phenotype.

Asunto(s)

Asunto(s)

RESUMEN

Research methodology using only one spouse to report for the couple has been questioned. Szinovacz (1983) reported higher rates of violence when both spouses responded to six items on Straus's Conflict Tactics Scale (CTS). The purpose of this study was to replicate her methodology by using all items measuring severe violence in the latest CTS scale with 94 military couples, to see if couple reports of violence indicated higher rates of violence compared to individual spouses' reports. Results were similar to Szinovacz's findings, and support the advisability of using both spouses to report violence in marriages.

Asunto(s)

Asunto(s)

RESUMEN

The purpose of the present study was to provide neurochemical and endocrinological evidence that dopamine (DA) neurons terminating in the intermediate lobe of the rat pituitary originate in the periventricular nucleus of the hypothalamus. One week following surgical separation of the periventricular nucleus from the mediobasal hypothalamus, DA and 3,4-dihydroxyphenyl-acetic acid (DOPAC) concentrations in the intermediate lobe were reduced by 50%, and this was accompanied by an increase in plasma alpha-melanocyte-stimulating hormone (alpha-MSH) concentrations. In contrast, this procedure had no effect on concentrations of prolactin in the plasma, or DA or DOPAC in the median eminence, the region of the mediobasal hypothalamus containing terminals of tuberoinfundibular DA neurons. Electrical stimulation of the periventricular nucleus increased the ratio of DOPAC/DA in the intermediate lobe and reduced the concentrations of alpha-MSH in the plasma, whereas in these same animals the DOPAC/DA ratio in the median eminence and concentrations of prolactin in the plasma were unaltered. These results indicate that approximately 50% of all the DA neurons terminating in the intermediate lobe of the rat pituitary originate in or project through the periventricular nucleus of the hypothalamus, and that these DA neurons regulate the secretion of alpha-MSH from intermediate lobe melanotrophs.

Asunto(s)

RESUMEN

The relative roles of dopaminergic and beta-adrenergic receptors in mediating the stress-induced increase in the secretion of alpha-melanocyte-stimulating hormone (alpha-MSH) from the intermediate lobe of the pituitary were determined in the male rat. Thirty minutes of physical immobilization (restraint stress) increased the circulating concentrations of alpha-MSH and decreased the 3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio in the intermediate lobe of the pituitary, reflecting a decrease in the tuberohypophysial dopaminergic neuronal activity. Pretreatment with the beta-adrenergic antagonist propranolol reduced the stress-induced increase in the circulating levels of alpha-MSH, but had no effect on the basal plasma concentrations of this hormone or the stress-induced decrease in DOPAC/DA in the intermediate lobe. If the dopaminergic tone during stress was maintained by administration of the DA agonist apomorphine, the stress-induced increase in alpha-MSH secretion was prevented. In nonstressed animals the administration of the beta 2-adrenergic agonist metaproterenol increased the plasma levels of alpha-MSH, and the effect of this drug was augmented if the inhibitory dopaminergic tone on alpha-MSH secretion was blocked by the administration of the DA antagonist haloperidol. Severing neurons in the retrochiasmatic region of the hypothalamus blocked the stress-induced decrease in DOPAC/DA in the intermediate lobe and attenuated the stress-induced increase in plasma concentrations of alpha-MSH. Taken together, these results indicate that a decrease in tuberohypophysial dopaminergic neuronal inhibitory tone and an increase in beta-adrenergic stimulation are both necessary for the full expression of the stress-induced increase in secretion of alpha-MSH from melanotrophs in the intermediate lobe of the rat pituitary.

Asunto(s)

RESUMEN

The effect of alpha-melanocyte-stimulating hormone (alpha MSH) on the activity of different central dopaminergic neurons in the male rat was determined by measuring the concentration of 3,4-dihydroxyphenylacetic acid (DOPAC) and the accumulation of 3,4-dihydroxyphenylalanine (DOPA) following the administration of a decarboxylase inhibitor in brain regions that contain terminals of nigrostriatal (striatum), mesolimbic (nucleus accumbens), tuberoinfundibular (median eminence) and tuberohypophysial (neural and intermediate lobe of the pituitary) dopaminergic neurons. Intracerebroventricular (i.c.v.) administration of alpha MSH caused a prompt (within 30 min) increase in the concentration of DOPAC and the accumulation of DOPA in the median eminence, but was without effect in the other brain regions. The alpha MSH-induced increase in tuberoinfundibular dopaminergic neuronal activity was temporally related to a decrease in circulating concentrations of prolactin. Twelve hours after the i.c.v. administration of prolactin DOPA accumulation increased in the median eminence but not in the neural or intermediate lobes of the pituitary. DOPA accumulation was not altered in any brain region 12 h after the i.c.v. administration of alpha MSH. These results suggest that alpha MSH acts acutely to selectively activate tuberoinfundibular dopaminergic neurons and thereby cause the secretion of prolactin from the anterior pituitary to decrease.

Asunto(s)

RESUMEN

Tuberohypophysial dopamine (DA) neurons terminate in the intermediate and neural lobes of the posterior pituitary. The objective of this study was to determine if concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC), a major metabolite of DA in these regions, reflect the activity of tuberohypophysial DA neurons. The concentrations of DOPAC and DA in the intermediate lobe were approximately twice those in the neural lobe, so that the ratios of DOPAC/DA were similar between lobes. The administration of a monoamine oxidase inhibitor pargyline produced a rapid decline (by 5 min) of DOPAC concentrations in both the intermediate and neural lobes. The administration of nomifensine, an inhibitor of DA uptake at the nerve terminal, produced a modest 33% decline in DOPAC concentrations in the intermediate lobe, but was without effect in the neural lobe. Activation of tuberohypophysial DA neurons by electrical stimulation of the pituitary stalk increased both the rate of DA synthesis (accumulation of dihydroxyphenylalanine (DOPA) after administration of the decarboxylase inhibitor NSD 1015) and the concentrations of DOPAC in the intermediate and neural lobes. Administration of the DA antagonist haloperidol increased, and the DA agonist apomorphine decreased both the rate of DOPA accumulation and DOPAC concentrations in the intermediate lobe but not the neural lobe. The results of the present study demonstrate that: (1) elimination of DOPAC from the intermediate lobe and neural lobe is rapid and alterations in DOPAC concentrations reflect dynamic changes in metabolism of DA; (2) DA which is released and recaptured is a minor contributor to DOPAC concentrations; and (3) alterations in the activity of tuberohypophysial DA neurons are accompanied by corresponding changes in DOPAC concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

RESUMEN

Administration of gamma-butyrolactone (GBL), an anesthetic which reduces dopaminergic neuronal activity, decreased the concentration of the dopamine (DA) metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the intermediate lobe of the pituitary gland, and increased alpha-melanocyte stimulating hormone (alpha MSH) concentrations in the serum of male rats. Bilateral electrical stimulation of the rostral arcuate nucleus, which contains perikarya of tuberohypophysial DA neurons, increased DOPAC concentrations in the intermediate lobe and decreased alpha MSH concentrations in the serum of GBL-anesthetized rats. Administration of the DA antagonist haloperidol prevented the decline in serum alpha MSH levels following arcuate nucleus stimulation, but had no effect on serum alpha MSH concentrations in sham-stimulated GBL-treated rats. These results indicate that GBL-induced decreases or stimulation-induced increases in the activity of tuberohypophysial DA neurons are accompanied by corresponding changes in the metabolism of DA in the intermediate lobe of the rat pituitary gland, and by reciprocal changes in the secretion of alpha MSH.

Asunto(s)

RESUMEN

The activity of nigrostriatal dopaminergic neurons has been estimated biochemically by measuring the rates of dopamine (DA) synthesis (accumulation of dihydroxyphenylalanine (DOPA) after NSD 1015) and turnover (decline of DA concentrations after alpha-methyltyrosine) in the striatum. It has been assumed that the activities of tuberoinfundibular dopaminergic (TIDA) and tuberohypophysial dopaminergic (THDA) neurons can also be estimated by making the same measurements in the terminals of these neurons in the median eminence and the posterior pituitary, respectively. In the present study, this assumption was tested directly by measuring the rates of DA synthesis and turnover in the median eminence and posterior pituitary following electrical stimulation of TIDS and THDA cell bodies in the arcuate nucleus. Electrical stimulation of the arcuate nucleus increased the rate of DOPA accumulation and the alpha-methyltyrosine-induced decline of DA concentrations in the median eminence and in the neural and intermediate lobes of the posterior pituitary. gamma-Butyrolactone (GBL), an anesthetic that selectively inhibits DA impulse flow, reduced the rates of DA synthesis and turnover in the median eminence. GBL also increased prolactin secretion which is tonically inhibited by DA released from TIDA neurons. Serum prolactin levels were significantly decreased by arcuate nucleus stimulation in GBL-anesthetized rats. These results indicate that the rates of DA synthesis and turnover within the median eminence and posterior pituitary reflect the activities of TIDA and THDA neurons, respectively.

Asunto(s)