Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Biogen”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,495 records · Page 83Linked to original sources
PubMedDate not supplied

The effect of ischemia on biogenic amine concentrations in the central nervous system.

A rabbit spinal cord ischemia model was used to study the effects of focal ischemia on the tissue concentrations of serotonin, 5-hydroxyindole acetic acid, and norepinephrine. Ischemia induced by abdominal aorta occlusion caused both serotonin and norepinephrine concentrations to decline in the most ischemic areas of the spinal cord by 55 minutes. In marginally perfused adjacent areas, serotonin concentrations transiently declined at 14 and 20 min. After the onset of ischemia and then returned to normal. The minimum was reached at the same time when previous studies showed damage had become irreversible in more ischemic regions. Concentrations of 5-hydroxyindole acetic acid did not change at any time and norepinephrine declined only in the most ischemic areas after damage was irreversible. Thus, permanent serotonin and norepinephrine decreases occur only in areas destined to be destroyed by infarction, but the serotonin returns to normal in marginal tissue that remains viable. These studies suggest that serotonin may be involved in the early stages of irreversible changes during central nervous system ischemia.

Animals↗
PubMed1986

Cerebrospinal fluid biogenic amine metabolites in children during treatment for acute lymphocytic leukemia.

To learn more about the impact of intrathecal methotrexate and cytosine arabinoside therapy on neuronal metabolism, we measured serial cerebrospinal fluid concentrations of homovanillic acid and 5-hydroxyindoleacetic acid, major metabolites of the neurotransmitters dopamine and serotonin, in children with acute lymphocytic leukemia. Multiple sequential cerebrospinal fluids were obtained from 30 children with acute lymphocytic leukemia evaluated prospectively from the time of diagnosis. We focused on the period of induction and intensification when children received weekly intrathecal chemotherapy. Paired cerebrospinal fluid specimens were also obtained at 3-month intervals from 60 children with acute lymphocytic leukemia in remission. Homovanillic acid and 5-hydroxyindoleacetic acid were measured using high performance liquid chromatography with electrochemical detection. We found that pretreatment metabolite values were no different from those in age-matched subjects in remission. In the first 5 wk of treatment, there were no significant changes in metabolite levels in patients treated exclusively with methotrexate. There was a transient decrease in homovanillic acid (-28 +/- 10%, p less than 0.001, Student's t test) and 5-hydroxyindoleacetic acid (-28 +/- 12%, p less than 0.05) in five of six patients after a single intrathecal dose of cytosine arabinoside. In the next 4 wk there was a gradual rise in levels of homovanillic acid (p = 0.001, by analysis of variance) and 5-hydroxyindoleacetic acid (p = 0.029, analysis of variance); this pattern did not correlate with administration of cranial irradiation. In children in remission, there were no significant changes in metabolite levels over a 3-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Changes of cerebral biopterin and biogenic amine metabolism in leukemic children receiving 5 g/m2 intravenous methotrexate.

Acute or subacute neurologic disorders can be observed in patients receiving high-dose methotrexate therapy for lymphoblastic leukemia or malignant tumor. Impairment of biopterin metabolism leading to decreased availability of monoamine neurotransmitters has been suggested to explain methotrexate neurotoxicity. To investigate such a mechanism, we have measured prospectively by HPLC the concentrations of total biopterin, homovanillic acid, and 5-hydroxyindolacetic acid in cerebrospinal fluid of 57 children with acute lymphoblastic leukemia. A sequential analysis of cerebrospinal fluid was performed for each patient: cerebrospinal fluid samples were obtained before therapy and after each of the four high-dose methotrexate infusions during the CNS prophylaxis phase. A significant increase of total biopterin concentrations in cerebrospinal fluid was observed after high-dose methotrexate therapy compared with the pretreatment values. No cumulative effect was noted. In contrast, no significant variation of the homovanillic acid and 5-hydroxyindolacetic acid levels was observed in cerebrospinal fluid. However, individual analysis revealed a transient decrease of homovanillic acid and 5-hydroxyindolacetic acid concentrations in cerebrospinal fluid of six children. The increase of total biopterin mimicking that observed in inherited dihydropteridine reductase deficiencies suggests that methotrexate inhibits the regenerating system of biopterin in the brain of patients undergoing high-dose methotrexate therapy.

Adolescent↗
PubMed1975

Effects of biogenic amines and TRH on release of prolactin and TSH in the rat.

The effects of a single injection of drugs on serum prolactin and TSH were determined in male and in estrogen-primed ovariectomized rats. The precursor of serotonin, 5-hydroxytryptophan(5-HTP), produced a significant rise in serum prolactin and TSH, whereas para chloroamphetamine, a depletor of serotonin, elicited a fall in serum prolactin and TSH. alpha-methylmetatyrosine (alpha-MMT) and reserpine, both depressors of brain catecholamine (CA) and serotonin levels, evoked significant increases in serum prolactin and reductions in serum TSH. Injection of alpha-MMT or reserpine together with 5-HTP further elevated serum prolactin but prevented any significant change in serum TSH. This suggests that the ability of alpha-MMT and reserpine to inhibit TSH release is mediated through a reduction in brain serotonin and not via a decrease in CA. alpha methylparatyrosine, which inhibits CA synthesis without altering serotonin, evoked a marked increase in serum prolactin but had no effect on serum TSH. L-dopa administration significantly reduced serum prolactin values but had no significant effect on serum TSH. Synthetic TRH increased both serum prolactin and TSH levels in male rats, but when it was injected after L-dopa administration, it did not elicit any rise in serum prolactin and evoked the same increase in serum TSH. This suggest that L-dopa acts directly or indirectly on the pituitary prolactin cells to inhibit TRH stimulation of prolactin release, but does not influence the action of TRH on pituitary TSH cells. Pilocarpine decreased serum prolactin, but had no significant effect on serum TSH values. The present study suggests that only serotonergic drugs produce similar effects on release of prolactin and TSH, whereas drugs that alter CA and pilocarpine depress prolactin release but have little or no effect of TSH.

5-Hydroxytryptophan↗
PubMed1976

Neurotransmitter regulation of growth hormone and ACTH in the rhesus monkey: effects of biogenic amines.

In an attempt to clarify the role of central neurotransmitters in GH and ACTH regulation, chair-adapted unanesthetized adult male rhesus monkeys and chronic indwelling intratrial cannulae were given 30 min infusions of various agonists known to affect central amines, and plasma samples were withdrawn for GH and cortisol determinations. Infusion of acid-saline vehicle alone had no significant effect on plasma GH or cortisol (P less than 0.05). L-Dihydroxyphenylalanine (L-Dopa) (4.5 and 45 mg/kg), but not apomorphine (7 mug/kg), a specific dopaminergic agonist, produced significant elevations of GH. Both noradrenergic (clonidine HCl, 1.5, 15, and 150 mug/kg, and D,L-threodihydroxyphenylserine (D,L-threodops) 90 mg/kg) and serotoninergic (5-hydroxy-L-tryptophan (5-HTP), 45 mg/kg) agonists induced significant GH responses. These findings suggest that GH is regulated in the rhesus monkey by noradrenergic and serotoninergic neurons, whereas participation of dopaminergic neurons has not been established. Significant cortisol responses were only observed following infusion of 5HTP (45 mg/kg). Dopaminergic and noradrenergic agonists not only failed to alter resting cortisol levels but also did not affect the cortisol response to 5-HTP. In the rhesus monkey serotoninergic mechanisms appear to be responsible for the regulation of resting cortisol levels. A catecholamine inhibitory mechanism was not demonstrated in this species.

5-Hydroxytryptophan↗
PubMed1976

Distribution of releasing factors, biogenic amines, and related enzymes in the bovine median eminence.

The bovine median eminence was dissected into eight different subdivisions: rostral, anterior internal, anterior external, middle external medial, middle external lateral, middle internal medial, middle internal lateral, and caudal. Thyrotropin-releasing hormone (TRH) was found in the highest concentrations in the middle external medial and lateral subdivisions; luteinizing hormone-releasing hormone (LHRH) was concentrated in the middle external lateral and anterior internal subdivisions. Among the various neurotransmitters and enzymes assayed, only dopamine and choline acetyltransferase were present in highest concentrations in the same subdivisions of the bovine median eminence found to be rich in TRH and LHRH. The distributions of norepinephrine, dopamine-beta-hydroxylase, serotonin, tryptophan hydroxylase, phenylethanolamine-N-methyltransferase, glutamic acid decarboxylase, and histamine appeared to correlate poorly with the major distributions of TRH and LHRH. These findings suggest that at the level of the median eminence, central neuroendocrine regulation of TRH and LHRH release may involve an interaction only with dopamine and acetylcholine.

Animals↗
PubMed1976

Biochemical and histochemical studies of biogenic amines in spinal cord trauma.

Highly sensitive enzymatic assays, microdissection techniques, and histochemical methods were used to investigate the effects of blunt trauma on rabbit spinal cord serotonin, norepinephrine, and dopamine concentrations. Within 5 minutes after trauma, norepinephrine and serotonin in gray matter decreased considerably at the lesion center. In white matter, norepinephrine decreased or was unchanged, but at the lesion edges serotonin increased. No changes in dopamine concentration were detected. Substantial changes in monoamines do occur after spinal cord trauma and serotonin may play a role in injury development.

Animals↗
PubMed2005

Role of biogenic amines and cHH in the crustacean hyperglycemic stress response.

In this study, we investigated (using bioassays and ELISA) the variation of cHH (crustacean hyperglycemic hormone) level in the eyestalks and hemolymph of Palaemon elegans (Rathke) (Decapoda, Caridea) following injection of serotonin (5-HT) and dopamine (DA) and correlated cHH profile with the variation in amount and time course of glycemia. 5-HT induced in P. elegans a rapid and massive release of cHH from the eyestalk into the hemolymph followed by hyperglycemia. On the contrary, DA did not significantly affect cHH release and hyperglycemia. In addition, we measured the level and variation of 5-HT in the eyestalk and hemolymph of P. elegans following copper contamination. The release of 5-HT from the eyestalk is very rapid and dose dependent. In the hemolymph, a peak of 5-HT occurs after 30 min, and again the circulating concentration of 5-HT is dose dependent on copper exposure. After 1 h, the level of 5-HT slowly decreases to basal level. The release of 5-HT from the eyestalk into the hemolymph after copper exposure precedes the release of cHH, confirming its role as a neurotransmitter acting on cHH neuroendocrine cells. The fact that copper induced a rapid and massive release of 5-HT from the eyestalk can explain its demonstrated role in inducing the release of cHH and the consequent hyperglycemia in intact but not eyestalkless animals.

Analysis of Variance↗
PubMed2000

Agonistic behaviour and biogenic amines in shore crabs Carcinus maenas.

To investigate the role of certain neurohormones in agonistic behaviour, fights were staged between pairs of size-matched male shore crabs Carcinus maenas, and blood samples were taken immediately after the contests had been resolved. Samples were also taken from these crabs at rest (before and after fighting) and after walking on a treadmill. A control group of crabs also had samples taken on each experimental day. Concentrations of tyramine, dopamine, octopamine, serotonin (5-HT) and norepinephrine were determined in each blood sample using a gas chromatography/mass spectrometry (GC-MS) system. Norepinephrine was not detectable in any of the samples, but the standards were recovered. Tyramine values were not significantly different between the control group and the fought group, so tyramine does not appear to be important in agonistic behaviour. A comparison between the control and fought groups shows that fighting had an effect on the concentrations of octopamine, dopamine and 5-HT, but exercise only had an effect on octopamine levels, which showed a reduction from resting values in both winners and losers. Resting and post-fight concentrations of octopamine, dopamine and 5-HT were higher in winners than in losers. 5-HT concentration increased in the blood of fought crabs from resting values, whereas dopamine concentration decreased. In winners, octopamine concentrations decreased from resting values, but in losers octopamine levels increased from resting concentrations. The escalatory behaviour or intensity of fighting performed by winners and losers was related to dopamine levels but not to those of octopamine or 5-HT. Therefore, there appears to be a link between relative concentrations of these three amines (dopamine, octopamine and 5-HT) and fighting ability; the effects are not simply a result of activity. The better competitors have higher concentrations of these three amines at rest and after fighting.

Agonistic Behavior↗