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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experiments were conducted to determine if Brown Leghorn chickens (Gallus domesticus) showed a daily differential responsiveness to the phased injections of corticosterone and prolactin. In experiment 1, 28 day old chicks, maintained on continuous lighting and a standard diet, were treated daily for 6 days with corticosterone (300 mug. in 0.2 cc. saline) and with prolactin (150 mug. in 0.2 cc. saline) for 4 days. The prolactin injections began 2 days after the first corticosterone injection. The interval between daily corticosterone injections at 1800 hours followed by prolactin injections 6, 12 or 18 hours later resulted in a significant increase in the liver lipidcontent in the chicks. However, when corticosterone and prolactin were given at the same time (1800 hours), no increase in liver lipid content was observed. Corticosterone admininstered at 6oo hours and followed by prolactin injections had no effect on liver lipid content regardless of the time of prolactin prolactin injections. Experiment 2 was designed to test the effect of the administration of corticosterone or prolactin alone at either 600 hours or 1800 hours on liver lipid metabolism. Two groups of Brown Leghorn chicks received prolactin alone (for 2 days) at either 600 hours or 1800 hours. None of these treatment groups were significantly different from the uninjected controls. It is concluded that the chick has a diurnal sensitivity to the effects of coritcosterone and that once the liver is affected by corticosterone, a temporal interaction between this steroid and prolactin can affect the liver lipid content of the Brown Leghorn chick.
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PMID:The temporal interaction of corticosterone and prolactin in affecting liver lipid metabolism of the chick. 93 29

Neuroendocrine and behavioral responses to a single 60-mg oral dose of the indirect serotonin agonist dl-fenfluramine were assessed in unmedicated adults with obsessive-compulsive disorder (OCD) and neuroendocrine results contrasted with those in normal control subjects. Net fenfluramine-induced prolactin release did not differ significantly between OCD patients and normal controls. Prolactin responses in the OCD group were not significantly correlated with baseline Yale-Brown Obsessive Compulsive Scale scores for either obsessions or compulsions, but were positively correlated with the baseline Hamilton Depression Scale score and Hamilton Anxiety Scale score. No clear difference in the severity of patients' obsessions or compulsions was found following challenge with fenfluramine versus placebo. Although the present study does not demonstrate a serotonergic abnormality in OCD, this may be more a reflection of limitations of the test procedures than evidence that central nervous system (CNS) serotonergic function is normal in the disorder.
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PMID:Neuroendocrine and behavioral responses to challenge with the indirect serotonin agonist dl-fenfluramine in adults with obsessive-compulsive disorder. 131 64

Prolactin is associated with the development of mammary tumors in rats. The aim of the present study was to evaluate whether strain differences in susceptibility to the development of mammary tumors could be explained by genetic differences in the response of the pituitary to chronic stimulation by estrogens. Prolactin levels were measured in plasma from rats of the Sprague-Dawley, Wistar WAG/Rij and Brown Norway BN/BiRij strains before and at different times after subcutaneous implantation of estradiol-17 beta in cholesterol/paraffin pellets. In all strains plasma prolactin was elevated from the second week after implantation of the pellet, although there were quantitative differences between the responses. At 32 weeks after implantation of the pellets the plasma level of prolactin in Sprague-Dawley rats was 1247 +/- 367 ng NIAMDD prolactin RP-1/ml (mean +/- S.E.M), whereas Wistar WAG/Rij and Brown Norway BN/BiRij had plasma prolactin levels of 679 +/- 211 and 182 +/- 19 ng/ml respectively. Between 52 and 104 weeks after implantation these values rose to 4016 +/- 1116, 5004 +/- 1053 and 808 +/- 129 ng/ml respectively. The plasma concentration of prolactin of rats in this age group was strongly associated with the occurrence of pituitary adenomas in all three strains. In untreated rats, the concentration of prolactin in the plasma increased with age to only 200-400 ng/ml at 12-24 months of age but no significant differences were observed between the three rat strains. It is concluded that observed differences in spontaneous and estrogen-mediated mammary tumor development in these rat strains cannot be explained by genetic differences in the plasma concentration of prolactin.
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PMID:Prolactin concentration in plasma and susceptibility to mammary tumors in female rats from different strains treated chronically with estradiol-17 beta. 674 39

The adaptive response of the neuroendocrine system to stress is known to be impaired during ageing, and this impairment may be genetically determined. To elucidate further the effect of genotype, inbred male rats of the Wistar-Kyoto (WKY) strain, characterized by their hyper-reactivity to stressors and shorter life span, were compared with Brown-Norway (BN) rats. In young BN rats, resting prolactin concentrations were lower than in WKY animals and were reduced with age, while in WKY rats they remained unchanged with age. In young rats of both strains prolactin concentrations were highest after subjecting them to stressful stimuli for 15 min. After 2 h of restraint stress (during which the animals were confined to a narrow space that restricted movement) prolactin concentrations in young rats returned to pre-stress values, while remaining high in aged rats of both strains. Concentrations of corticotrophin (or adrenocorticotrophic hormone, ACTH) were lower in BN than in WKY rats and did not change with age in either strain. After 2 h of stress, ACTH concentrations were still slightly higher than normal in both young and aged BN rats, but not in WKY rats. Corticosterone concentrations were similar in young WKY and BN rats and were reduced in aged rats of both strains. After 2 h of stress, corticosterone concentrations were still high in aged, but not in young rats of both strains. However, this stress-induced increase was larger (3.7 times as much) in the BN strain than in the WKY strain (in which the increase was 1.7 times as much). The concentrations of hypothalamic monoamines were similar in young rats of both strains, although stress resulted in reduced noradrenaline concentrations, as previously documented, and in minor increases in 3,4-dihydroxyphenylacetic acid in both strains. During ageing, basal noradrenaline concentrations were reduced only in WKY rats, while the amount of 5-HT increased selectively in BN rats. Concentrations of 5-hydroxyindoleacetic acid were increased after stress in aged WKY rats only. The results demonstrate that resting plasma concentrations of the stress hormones ACTH and corticosterone and of prolactin are lower in BN than in WKY rats. In ageing, however, the stress-induced increases in the concentrations of these hormones are relatively higher in the BN strain, which is characterized by a longer life span.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of genotype on age-related alterations in the concentrations of stress hormones in plasma and hypothalamic monoamines in rats. 768 29

In man, aging is associated with both primary and secondary testicular dysfunction. In contrast, most studies in male rat models of aging have demonstrated only secondary testicular failure. We previously reported that testes from aging male F344 rats secrete excessive progesterone (P), which may suppress gonadotropin secretion and confound aging studies. To determine whether the male Brown Norway (BN) rat is a more suitable aging model, trunk blood was collected from intact (sham-operated) and orchidectomized young (3 mo), middle-aged (13 mo), old (23 mo), and senescent (28-30 mo) animals. Testosterone (T), estradiol (E2), P, prolactin (PRL), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured by RIA. In intact rats, T levels declined with aging, while LH was unchanged, and FSH increased progressively with aging. In contrast to F344 rats, no age-related increases in P or E2 occurred, nor did PRL or other steroid hormones increase. In the absence of testicular feedback (orchidectomized rats), FSH and LH declined progressively with aging. These findings suggest that, as in men, aging male BN rats manifest both primary and secondary testicular failure, and do not exhibit decreased gonadotropin levels secondary to excessive steroid or PRL secretion. Therefore, the BN rat appears to be the best available rat model for studies of male reproductive aging.
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PMID:The Brown Norway rat as a model of male reproductive aging: evidence for both primary and secondary testicular failure. 812 45

Brown trout, with indwelling dorsal aortic cannulae, were exposed to various concentrations of aluminium (Al; 50 micrograms liter-1, 100% mortality over 48 hr; 25 micrograms liter-1, 50% mortality over 120 hr; 12.5 micrograms liter-1, 0% mortality over 120 hr) in acidic (pH 5.0) soft water. The plasma concentrations of prolactin (PRL), cortisol, thyroxine (T4), and triiodothyronine (T3) were monitored. Plasma PRL concentrations were transiently depressed (to less than 20% of resting concentrations) after 12 hr in trout in the two highest water Al concentrations, but were unchanged in the trout exposed to 12.5 micrograms liter-1 Al. Plasma cortisol concentrations were elevated in response to all water Al levels and remained elevated in trout in the lethal conditions. The sublethally exposed trout showed a recovery in plasma cortisol concentrations by 120 hr. Plasma T4 concentrations were significantly elevated in trout exposed to both the lethal and the sublethal Al concentrations (from mean resting concentrations of 1-2 ng ml-1 to peaks of 8.9 and 9.0 ng ml-1 in the 50 and 12.5 micrograms liter-1 Al groups, respectively), although a recovery in plasma concentrations was evident in the sublethally exposed trout from 72 hr onwards. Plasma T3 concentrations were relatively stable in the trout exposed to the two highest doses of Al, whereas the trout under the lowest, sublethal, Al conditions exhibited a sustained (12-72 hr) elevation in plasma T3 concentrations (from a mean resting concentration of 0.9 ng ml-1 to a peak of 4.2 ng ml-1 at 48 hr). No clear relationship was apparent between the plasma PRL concentrations and the previously reported ionoregulatory status of the trout.
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PMID:Plasma prolactin, cortisol, and thyroid responses of the brown trout (Salmo trutta) exposed to lethal and sublethal aluminium in acidic soft waters. 880 68

Some inbred strains of rats showed behavioural differences in the forced swimming test, which is considered a putative animal model of depression. In the present work, the behavioural and physiological responses to forced swimming were studied in male and female rats of five inbred strains of rats: Brown-Norway (BN), Fischer 344 (FIS), Lewis (LEW), Spontaneously Hypertensive (SHR) and Wistar-Kyoto (WKY). Physiological measures were aimed at characterizing emotional reactivity, a very important issue which has usually been approached by studying a single endocrine system, and its relationship to the forced swimming behaviour. The four indices of reactivity to stress used were serum glucose, ACTH, corticosterone and prolactin. No behavioural differences between sexes were observed in the forced swimming test. In addition, BN and WKY rats showed passive behaviour compared with the other three strains, the FIS strain being the most active. Whereas only minor differences were found in the resting levels of the variables studied with regard to either sex or strain, pituitary-adrenal (PA) and glucose responses to 15 min forced swimming differed among sexes and strains. Stress-induced hyperglycaemia was lowest in WKY and highest in SHR, being lower in females than in males. The lowest ACTH and corticosterone responses to forced swimming were observed in LEW and the highest in FIS. Female rats showed a clearly higher PA response to stress in all strains. Prolactin response to stress was very similar between sexes and strains. It might thus be concluded that: (i) there are important inter-strain differences in the forced swimming behaviour, with no differences between sexes; (ii) the various physiological indices of emotional reactivity follow a different trend and no warranted conclusion on differences in emotional reactivity should be based upon a single endocrine system or even only upon physiological measures; (iii) we cannot be sure, therefore, whether or not there are differences in emotionality between the strains studied in spite of well-established inter-strains differences in the forced swimming behaviour.
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PMID:Comparison of the behavioural and endocrine response to forced swimming stress in five inbred strains of rats. 883 94

Reproductive aging in the Brown Norway rat occurs because of testicular as well as hypothalamic-pituitary dysfunction. Excitatory amino acids (EAA) participate in the regulation of pulsatile secretion of hypothalamic GnRH and pituitary LH. In the present study, we studied the EAA-GnRH-LH axis for possible age-related alterations in prepubertal (35 days), young (3-4 months), middle-aged (12-13 months) and old (21-23 months) rats. In the first experiment, an intra-atrial cannula was implanted in rats of different ages to evaluate the pituitary response to small, physiological intravenous bolus administration of GnRH (0.5 or 1.0 nmol/100 g body weight). The results showed no age-related significant differences in in-vivo serum LH or FSH responsiveness to GnRH. In a second experiment, blood samples for the gonadotropins were withdrawn immediately before and 10 min after an iv injection of the glutamate receptor agonist N-methyl-D-aspartate (NMDA; 5 mg/kg, a dose that induces a physiological LH pulse in young rats). Administration of NMDA induced significant increases in LH and prolactin in all groups of animals (P<0.05) and a significant FSH response in young and middle-aged but not old rats. NMDA-induced LH, FSH and prolactin release was higher (P<0.05) in prepubertal rats than in all other age groups. Compared with young rats, NMDA-induced increase in plasma LH and prolactin was lower (P<0.05) in old rats. In the third experiment, to ascertain whether this reduced LH response to NMDA in old rats was exerted at the hypothalamic level, the effects of NMDA on GnRH release in vitro from preoptic area-medial basal hypothalamus (POA-MBH) fragments were compared among rats of different ages. GnRH efflux in response to NMDA was significantly attenuated with increasing age. GnRH release in vitro was higher in prepubertal and lower in old than in young rats (P<0.05). Lastly, we measured amino acid concentrations in hypothalamic tissue (POA-MBH fragments). Prepubertal rats had higher levels of glutamate and taurine than young rats. Significant reductions in glutamate and gamma-aminobutyric acid (GABA) levels were found in old compared to young rats. In conclusion, these results showed that the hypothalamic NMDA-GnRH-LH axis was altered in old rats. The decreased hypothalamic content of some of the EAA and the reduced responsiveness of GnRH neurons to NMDA (both in vivo and in vitro) may contribute to an altered LH pulsatile secretion observed in old rats.
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PMID:Aging results in attenuated gonadotropin releasing hormone-luteinizing hormone axis responsiveness to glutamate receptor agonist N-methyl-D-aspartate. 953 55

In order to study the genetic factors involved in the neuroendocrine responses to stress, we have compared the intensity of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system activation following a 60 minute-restraint stress or after a 10 minute-exposure to a novel environment in three rat strains : outbred Wistar, inbred Brown Norway and Fischer 344, and F1 hybrid Brown Norway x Fischer 344 rats. The basal activity of the HPA axis did not differ between the four groups of rats whereas Brown Norway rats had the lowest release of corticosterone following restraint stress. Although differences in plasma adrenocorticotropic hormone failed to reach significance after exposure to a novel environment, the lowest level of corticosterone was found in Brown Norway rats. This lower release of corticosterone in Brown Norway rats has probably an adrenal origin as suggested by the ratios of corticosterone to ACTH levels following exposure to a novel environment: 632 +/- 222, 200 +/- 45, 636 +/- 89, 258 +/- 65 in Wistar, Brown Norway, Fischer 344 and F1 hybrids, respectively. This trait was dominant over the "adrenal responsive" phenotype of the Fischer 344 rat strain. In response to novelty, the lowest levels of prolactin and renin activity were found in plasma of Brown Norway and Wistar rats and the highest in Fischer 344 and F1 hybrid Brown Norway x Fischer 344 rats, the "high response" phenotype of the Fischer 344 strain being dominant. No strain-related difference was found in plasma glucose and either adrenal tyrosine hydroxylase or phenylethanolamine N-methyl transferase activity. Taken together, these data suggest that 1) genetic factors might contribute to the interindividual differences in neuroendocrine responses to stress and 2) subsets of these responses are controlled by specific genetic factors.
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PMID:Comparison of the neuroendocrine responses to stress in outbred, inbred and F1 hybrid rats. 967 42

Many studies support a significant relation between low cholesterol levels and poor impulse, aggression and mood control. Evidence exists also for a causal link between low brain serotonin (5-HT) activity and these behaviors. Mechanisms linking cholesterol and hostile or self-destructive behavior are unknown, but it has been suggested that low cholesterol influences 5-HT function. This study was designed to explore the relationship between plasma cholesterol, measures of impulsivity and aggression, and indices of 5-HT function in personality disordered cocaine addicts. Thirty-eight hospitalized male patients (age 36.8+/-7.1) were assessed with the DSM-III-R, the Buss-Durkee Hostility Inventory (BDHI), the Barratt Impulsiveness Scale (BIS) and the Brown-Goodwin Assessment for Life History of Aggression. Fasting basal cholesterol (total, LDL and HDL) was determined 2 weeks after cocaine discontinuation. On the same day 5-HT function was assessed by neuroendocrine (cortisol and prolactin) and psychological (NIMH and 'high' self-rating scales) responses following meta-chlorophenylpiperazine (m-CPP) challenges. Reduced neuroendocrine responses, 'high' feelings and increased 'activation-euphoria' following m-CPP have been interpreted as indicating 5-HT alterations in a variety of psychiatric conditions. Significantly lower levels of HDL cholesterol were found in patients who had a history of aggression (P=0.005). Lower levels of HDL cholesterol were also found to be significantly associated with more intense 'high' and 'activation-euphoria' responses as well as with blunted cortisol responses to m-CPP (P=0.033, P=0.025 and P=0.018, respectively). This study gives further support to existing evidence indicating that in some individuals, the probability of exhibiting impulsive and violent behaviors may be increased when cholesterol is low. It also suggests that low cholesterol and alterations in 5-HT activity may be causally related.
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PMID:Low HDL cholesterol, aggression and altered central serotonergic activity. 1072 26


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