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Pradeep J Nathan

Publications and source records attributed to Pradeep J Nathan.

43 records · Page 3Linked to original sources
PubMed2003

The modulatory effects of dopamine D1 and D2 receptor function on object working memory in humans.

The role of dopamine D1 and D2 receptors in modulating object working memory in humans is poorly understood. The current study was designed to investigate the effects of D1 and D2 receptor modulation on object working memory. Twelve healthy subjects underwent testing under three conditions (0.05 mg pergolide (D1/D2 receptor agonist), 2.5 mg bromocriptine (D2 receptor agonist) and placebo] in a double-blind, placebo-controlled repeated measures design. Subjects performed the object working memory N-back task pre-drug and 1.5 h and 3 h post-drug administration. Neither pergolide nor bromocriptine had an effect on object working memory performance. These findings suggest that object working memory may not be modulated by D1 and D2 receptors in humans.

Adolescent↗
PubMed2002

The acute nootropic effects of Ginkgo biloba in healthy older human subjects: a preliminary investigation.

Ginkgo biloba has been shown to have chronic memory enhancing effects in healthy subjects and patients with dementia. There is limited research on the acute nootropic effects of Ginkgo biloba in humans. The current study aimed to examine the acute effects of Ginkgo biloba (120 mg) on memory functioning in healthy older volunteers using the cognitive drug research (CDR) battery of memory tests and the Rey auditory verbal learning task (AVLT). The study was a double-blind placebo-controlled design, with each participant tested under both placebo and Ginkgo biloba treatment conditions. Testing was conducted pre- and 90 min post-drug administration for each treatment condition. Treatment conditions were separated by a 7 day wash out period. No acute effects of Ginkgo biloba were found for any of the memory tests examined. The findings suggest that 120 mg of Ginkgo biloba has no acute nootropic effects in healthy older humans.

Aged↗
PubMed2002

Effects of serotonin and catecholamine depletion on interleukin-6 activation and mood in human volunteers.

There is increasing evidence that depression and related neurotic illnesses are associated with alterations in immune function that may contribute to their pathogenesis. For example, clinical and experimental studies have shown that abnormal HPA-axis activation and monoamine neurotransmission may be related to an increased release of proinflammatory cytokines from stimulated lymphocytes in the periphery and brain. In the present investigation, the effects of tryptophan depletion (TD) on unstimulated plasma interleukin-6 (IL-6) concentrations were investigated in order to determine whether acute changes in serotonin (5-HT) neurotransmission would induce a proinflammatory response in healthy individuals. The effects of TD were compared with the analogous procedure of tyrosine depletion (TPD), which reduces catecholamine metabolism in humans. Thirteen female participants completed three experimental sessions: TD, TPD and a balanced-control condition (B). Mood-ratings and blood sampling were performed at baseline and 5 h after the administration of the mixtures. Analyses revealed that TD and TPD markedly reduced tryptophan and tyrosine/phenylalanine levels, respectively. No changes in plasma IL-6 production or ratings of lowered mood were observed, however, subjects did report feeling more fatigued after TD. These findings indicate that a transient disruption in global monoamine function does not stimulate a proinflammatory response of IL-6 in normal volunteers.

Adult↗
PubMed2002

Brain monoamines and early visual information-processing speed.

Visual inspection time (IT) is a measure of information-processing speed, which correlates reliably with psychometric intelligence. Pharmacological research into IT indicates that manipulation of the cholinergic system modulates performance on the IT task, however the contribution of other neurotransmitters to this modality remains unclear. This study was designed to examine the effects of low brain serotonin and catecholamine availability on IT using the established method of amino-acid precursor depletion. Female participants (n=13) completed three experimental sessions; tryptophan depletion (TD); tyrosine/phenylalanine depletion (TPD); and a balanced control condition (B) in a randomized, double-blind cross-over design. IT assessments were performed at baseline and approx. 5 h post-mixture administration. IT scores were unaffected by either of the treatment conditions. These findings suggest that monoamines, whilst implicated in various forms of cognition are not central to IT, which measures the efficiency of perceptual intake and information-processing speed.

Adult↗
PubMed2002

A review of the status of Western herbal medicine in Australia.

Western herbal medicine is the most widely used form of herbal medicine in Australia although Ayurvedic and Chinese herbal medicines are becoming better known. The agricultural production and manufacture of locally grown herbs is, with some exceptions, relatively underdeveloped, as is the research and development of indigenous flora. However, the use of herbal medicine is increasingly becoming mainstream with retail sales of herbal products in Australia estimated to be 200 million dollars. Concurrent with the increase in popularity of herbal medicine with health consumers have come advances in herbal medicine education and regulation. Although small by European standards, research into herbal medicines is increasing, mainly through industry and University-based initiatives.

Journal Article↗