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Biomedical subjects

L McMahon

Publications and source records attributed to L McMahon.

30 records · Page 2Linked to original sources
PubMed1995

Isobolographic assessment of the effects of combinations of phenylpropanolamine and fenfluramine on food intake in rats.

Phenylpropanolamine (PPA) suppresses appetite in rats via activation of alpha 1-adrenergic receptors within the paraventricular hypothalamus (PVN). The serotonergic (5-HT) agonist fenfluramine (FEN) is thought to suppress appetite via stimulation of 5-HT release within the PVN rather than activation of adrenergic receptors. Whether a mixture of these neurochemically distinct anorexic drugs will serve as an effective appetite suppressant is unknown. In the present experiment, drug-drug interactions between PPA and FEN were explored using an isobologram technique. Fixed doses of PPA (0 vs. 5 mg/kg) were combined with various doses of FEN (1.25, 2.5, and 5.0 mg/kg) and fixed doses of FEN (0 vs. 2.5 mg/kg) were combined with various doses of PPA (0, 5, 10, and 15 mg/kg). Drug combinations were injected IP 30 min before a 1-h feeding trial in 16-h food-deprived rats. PPA and FEN were dose-additive in this paradigm, an outcome that supports the feasibility of a new appetite suppressant composed of a mixture of PPA and FEN.

Animals↗
PubMed1993

Modulation of feeding by hypothalamic paraventricular nucleus alpha 1- and alpha 2-adrenergic receptors.

Noradrenergic receptor populations within the paraventricular hypothalamus (PVN) modulate feeding. Satiated rats exhibit enhanced feeding subsequent to activation of alpha 2-adrenergic receptors within the PVN induced by exogenous infusion of either norepinephrine (NE) or clonidine (CLON). The feeding-stimulatory effect of alpha 2-adrenergic agents presumably reflects an inhibitory action on receptors located on medial hypothalamic "satiety" cells. Adrenergic receptors of the alpha 1-subclass have been identified within the PVN which are excitatory and which may function to suppress food intake. Microinjection into rat PVN of various alpha 1-adrenergic agonists including cirazoline, methoxamine, phenylpropanolamine and phenylephrine suppress feeding; an effect that is reversed by pretreatment with alpha 1-adrenergic receptor antagonists. The present review argues that alpha 1- and alpha 2-adrenoceptors within brain and specifically within the PVN are organized in an antagonistic fashion and that the effects of various adrenergic agonists on feeding may reflect the degree to which these agonists act at alpha 1- and alpha 2-adrenoceptors as well the relative balance of these receptors and their activity within the PVN.

Adrenergic alpha-Agonists↗
PubMed1993

Effects on food and water intake of the alpha 1-adrenoceptor agonists amidephrine and SK&F-89748.

Activation of alpha-1 adrenoceptors, via systemic injection of agonists such as cirazoline and phenylpropanolamine (PPA), reliably suppresses food intake in rats. These effects are thought to result from stimulation of central alpha 1-adrenoceptors within the rat paraventricular hypothalamic nucleus (PVN), based on studies in which direct injections of cirazoline, methoxamine, phenylephrine and PPA into PVN suppress food intake. Because relatively few alpha 1-agonists have been tested to date using the systemic route of exposure, the present study examined the effects of the alpha 1-adrenoceptor agonists amidephrine and SKF-89748 on food and water intake. Adult male rats received systemic injections (IP) of either amidephrine (0.025, 0.05, 0.01 mg/kg) or of SK&F 89748 (0.01, 0.02, and 0.04 mg/kg). Amidephrine markedly suppressed food intake (ED50 = 0.49 mg/kg) and water intake (ED50 = 0.50 mg/kg), while SK&F 89748 marginally suppressed food intake (ED50 = 0.37 mg/kg) and was less potent in suppressing water intake (ED50 = 0.76 mg/kg). These results document that systemic injection of the alpha 1-adrenoceptor agonists amidephrine and SK&F 89748 induces anorexia with amidephrine exerting greater potency than SK&F 89748. These results further support the hypothesis that stimulation of alpha 1-adrenoceptors suppresses food intake.

Adrenergic alpha-Agonists↗
PubMed1990

Three is company.

'Caring for people in Cornwall' is a project that involved GPs, the FHSA (Family Health Services Authority) and the HA (Health Authority) as three equal partners. Laurie McMahon explains how it evolved.

Community Health Services↗
PubMed1990

Keep it integrated.

Explore the source record for details and available documents.

Community Health Services↗
PubMedDate not supplied

Co-evolution of glucose-6-phosphate dehydrogenase deficiency and quinine taste sensitivity.

We hypothesized that 'quinine' taste sensitivity functions to regulate the intake of bitter-tasting, naturally occurring antimalarial substances of plant origin, and that this genetic trait has co-evolved with the G6PD locus. This hypothesis was tested by evaluating taste sensitivity to quinine sulphate and sodium chloride among 17 G6PD-deficient and 25 G6PD-normal African American subjects 14-40 years of age. There was no significant difference in mean 'quinine' taste sensitivity between the two groups, although there was a trend towards greater 'quinine' taste acuity among the G6PD-deficient subjects. A larger study sample would provide a fairer test of the hypothesis.

Adolescent↗