The role of serotonin release and autoreceptors in the dorsalis raphe nucleus in the control of serotonin release in the cat caudate nucleus

Abstract Rationale Cytochrome P450 2D (CYP2D) enzymes metabolize many addictive drugs, including methamphetamine. Variable CYP2D metabolism in the brain may alter CNS drug/metabolite concentrations, consequently affecting addiction liability and neuropsychiatric outcomes; components of these can be modeled by behavioral sensitization in rats. Methods To investigate the role of CYP2D in the brain in methamphetamine-induced behavioral sensitization, rats were pretreated centrally with a CYP2D irreversible inhibitor (or vehicle) 20 h prior to each of 7 daily methamphetamine (0.5 mg/kg subcutaneous) injections. In vivo brain microdialysis was used to assess brain drug and metabolite concentrations, and neurotransmitter release. Results CYP2D inhibitor (versus vehicle) pretreatment enhanced methamphetamine-induced stereotypy response sensitization. CYP2D inhibitor pretreatment increased brain methamphetamine concentrations and decreased the brain p-hydroxylation metabolic ratio. With microdialysis conducted on days 1 and 7, CYP2D inhibitor pretreatment exacerbated stereotypy sensitization and enhanced dopamine and serotonin release in the dorsal striatum. Day 1 brain methamphetamine and amphetamine concentrations correlated with dopamine and serotonin release, which in turn correlated with the stereotypy response slope across sessions (i.e., day 1 through day 7), used as a measure of sensitization. Conclusions CYP2D-mediated methamphetamine metabolism in the brain is sufficient to alter behavioral sensitization, brain drug concentrations, and striatal dopamine and serotonin release. Moreover, day 1 methamphetamine-induced neurotransmitter release may be an important predictor of subsequent behavioral sensitization. This suggests the novel contribution of CYP2D in the brain to methamphetamine-induced behavioral sensitization and suggests that the wide variation in human brain CYP2D6 may contribute to differential methamphetamine responses and chronic effects.

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Role of brain serotonergic pathways and hypothalamus in regulation of renin secretion

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.253.1.r179 ◽

1987 ◽

Vol 253 (1) ◽

pp. R179-R185

Author(s):

E. Gotoh ◽

K. Murakami ◽

T. D. Bahnson ◽

W. F. Ganong

Keyword(s):

Plasma Renin ◽

Dorsal Raphe ◽

Raphe Nucleus ◽

Renin Secretion ◽

Sodium Diet ◽

Low Sodium Diet ◽

Low Sodium ◽

Head Up Tilt ◽

Dorsal Raphé

To investigate the role of brain serotonergic neurons in the regulation of renin secretion, we measured changes in plasma renin activity (PRA), and, in some instances, plasma renin concentration (PRC), plasma angiotensinogen, and plasma adrenocorticotropic hormone (ACTH) in rats with lesions of the dorsal raphe nucleus and lesions of the paraventricular nuclei, dorsomedial nuclei, and ventromedial nuclei of the hypothalamus. We also investigated the effects of p-chloroamphetamine (PCA), immobilization, head-up tilt, and a low-sodium diet in the rats with dorsal raphe, paraventricular, and dorsomedial lesions. Lesions of the dorsal raphe nucleus abolished the increase in PRA produced by PCA but had no effect on the increase produced by immobilization, head-up tilt, and a low-sodium diet. Paraventricular lesions, which abolish the increase in plasma ACTH produced by PCA, immobilization, and head-up tilt, decreased plasma angiotensinogen. The paraventricular lesions abolished the PRA and the PRC responses to PCA and the PRA but not PRC response to immobilization, head-up tilt, and a low-sodium diet. The ventromedial lesions abolished the PRA and PRC responses to PCA and did not reduce plasma angiotensinogen. The data suggest that paraventricular lesions depress angiotensinogen production by the liver and that the paraventricular and ventromedial nuclei are part of the pathway by which serotonergic discharges increase renin secretion. They also suggest that the serotonergic pathway does mediate the increases in renin secretion produced by immobilization, head-up tilt, and a low-sodium diet.

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Role of Gabaergic and Glycinergic Transmissions in the Substantia Nigra in the Regulation of Dopamine Release in the Cat Caudate Nucleus

Amino Acids as Chemical Transmitters ◽

10.1007/978-1-4613-4030-0_30 ◽

1978 ◽

pp. 413-423 ◽

Cited By ~ 1

Author(s):

A. Chéramy ◽

A. Nieoullon ◽

J. Glowinski

Keyword(s):

Substantia Nigra ◽

Caudate Nucleus ◽

Dopamine Release

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Cathepsin G-dependent platelet stimulation by activated polymorphonuclear leukocytes and its inhibition by antiproteinases: role of P-selectin-mediated cell-cell adhesion

Blood ◽

10.1182/blood.v81.11.2947.bloodjournal81112947 ◽

1993 ◽

Vol 81 (11) ◽

pp. 2947-2957 ◽

Cited By ~ 1

Author(s):

V Evangelista ◽

P Piccardoni ◽

JG White ◽

G de Gaetano ◽

C Cerletti

Keyword(s):

Functional Role ◽

Polymorphonuclear Leukocytes ◽

Platelet Adhesion ◽

Inhibitory Effect ◽

Serotonin Release ◽

Cathepsin G ◽

Inhibitory Antibody ◽

Neuraminidase Treatment

Human PMN stimulated by fMLP are able to activate coincubated, autologous platelets. Cathepsin G, a neutral serine protease stored in the azurophilic granules of PMN, is the major platelet activator in this system. We previously proposed that shear-induced close PMN- platelet contact creates the conditions for which cathepsin G activity on platelets is protected against antiproteinases. The aim of this study was to investigate the adhesive mechanisms, possibly creating between PMN and platelet membranes the microenvironment in which cathepsin G, discharged from stimulated PMN onto adherent platelets, is protected against antiproteinases. Microscopic examination showed that under conditions of high shear, 71.3% +/- 6.1% of PMN were associated to platelets forming small clumps. This percentage decreased to 10% +/- 2% and 13% +/- 4%, respectively, in the presence of an inhibitory antibody to P-selectin or 20 mmol/L mannose-1-phosphate and to 10.8% +/- 3.7% when cells were not stirred. Similarly, PMN pretreatment with neuraminidase abolished PMN binding to platelets. These results indicate that P-selectin mediates PMN-platelet adhesion occurring before PMN stimulation. Prevention of PMN-platelet contact significantly potentiated the inhibitory effect of alpha 1-protease inhibitor on subsequent cathepsin G-induced platelet serotonin release. Because anti-P-selectin antibody, mannose-1-phosphate, and neuraminidase treatment of PMN did not modify PMN-induced platelet activation in the absence of antiproteinases, it is suggested that P- selectin-mediated PMN-platelet adhesion results in the formation of a sequestered microenvironment between cell membranes, in which higher amounts of antiproteinases are required to prevent the activity of released cathepsin G. These data add a new functional role to P- selectin-mediated PMN-platelet adhesion that could be important in vivo because of the presence of antiproteinases in plasma.

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