Effects of active immunization against gonadotrophin-releasing hormone on the concentrations of noradrenaline, dopamine, 5-hydroxytryptamine and some of their metabolites in the brain and sexual organs of male rats

This is an investigation of the effects of active immunization against gonadotrophin-releasing hormone (GnRH) conjugated to keyhole limpet hemocyanin on brain and male sexual organ concentration of catecholamines and 5-hydroxytryptamine. The treatment induces antibodies against GnRH with consequent interference with reproductive function as indicated by the attendant decrease in serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone. Rat striatal and mesolimbic dopamine levels were moderately increased by this treatment but no changes were observed in the hypothalamus. GnRH immunization also increased brain 5-hydroxytryptamine concentrations as observed in the hypothalamus, olfactory tubercles and striatum. In the male accessory sexual organs, immunity against GnRH alters the density of noradrenergic concentration. The changes occurred in opposite directions in the different regions investigated; increases in noradrenaline were observed in the prostate, with a reduction being detected in the epididymus and no changes were observed in the vas deferens or the seminal vesicles. 5-Hydroxytryptamine levels increased in the vas deferens but no effects were observed in the epididymus, prostate or seminal vesicle. It is concluded that GnRH immunization with the consequent reductions in circulating FSH, LH and testosterone are associated with changes in neurotransmitter concentration both in the brain and in some of the accessory sexual organs in the male rat.     

Clinical experience with a new detection algorithm for differentiation of supraventricular from ventricular tachycardia in a dual-chamber defibrillator

INTRODUCTION: Inadequate therapy for supraventricular tachyarrhythmias (SVT) is a frequent problem of implantable cardioverter defibrillators (ICD). Dual-chamber ICDs have been developed to improve discrimination of SVT from ventricular tachycardia (VT). We investigated the positive predictivity, sensitivity, and specificity of a new algorithm, the SMART detection trade mark algorithm, incorporated in the Phylax AV (Biotronik) dual-chamber ICD. METHODS AND RESULTS: Two hundred nine patients (185 men, age 64 +/- 11 years) received a Phylax AV ICD with SMART detection trade mark activated. In 138 of these patients, 1,245 sustained tachycardia episodes with a detailed electrogram were stored in the device during a follow-up period of 10 +/- 6 months. Episodes were correctly classified as ventricular fibrillation (VF, n = 178) in 52 patients, VT (n = 641) in 98 patients, and SVT (n = 385) in 48 patients by the algorithm. Forty-one true SVT episodes (3.3%) were misclassified as VT: atrial fibrillation (n = 7) and flutter (n = 1), sinus tachycardia (n = 12), and other SVT (n = 21). The positive predictivity for VF/VT was 94.5% (95% CI 92.7-95.8) uncorrected and 94.5% (95% CI 92.9-95.8%) corrected with the generalized equation estimation (GEE) method. The positive predictivity for SVT was 100%. The specificity was 88.9% (95% CI 85.6-91.6%) uncorrected and 89.0% (95% CI 85.6-91.6%) corrected with the GEE method with a sensitivity of 100%. CONCLUSION: The SMART detection trade mark algorithm was safe and reliable for the detection of all ventricular tachycardias. Although its specificity was high, it should be improved with regard to SVT to avoid inappropriate ICD therapies.     

Catecholamines and 5-hydroxytryptamine in nervous tissue of cephalopods

1. Catecholamines and 5-hydroxytryptamine were measured fluorimetrically in nervous tissue of cephalopod molluscs.

2. The only catecholamines found present in nervous tissue of Eledone, Octopus and Sepia were dopamine and noradrenaline. The highest concentrations were found in the optic lobes and in the superior buccal lobe. The concentrations of dopamine and noradrenaline were smaller in other regions of the nervous tissue taken.

3. 5-Hydroxytryptamine was also found in most of the regions investigated. The highest concentration was found in the inferior buccal ganglia and in the optic lobes.

4. The administration of reserpine produced a marked decrease in the concentration of catecholamines and 5-hydroxytryptamine in octopod nervous tissue.

5. These findings suggest that dopamine, noradrenaline and 5-hydroxytryptamine may function as neurotransmitters in cephalopod molluscs.

     

Adrenaline in bird brain

1. Catecholamine estimations were made on the whole diencephalon and on the hypothalamus of pigeons and fowls using fluorimetry of the acetylated amines as one, and bio-assay after chromatographic separation of the amines as a second method.

2. There was no significant difference between the results obtained by the two methods; for pigeons mean percentage methylation was 10% with one and 12% with the other technique, and in the Rhode Island Red breed of fowls the corresponding figures were 28 and 31%.

3. The percentage methylation for the hypothalamus of another breed of fowls (Plymouth Rock) was the same as in Rhode Island Red, but it was significantly lower in White Leghorn birds.

4. Between the ages of 3·5 weeks and maturity the percent methylation remained unchanged.

5. There is no evidence to suggest that bio-assay of adrenaline as used in this and previous work lacks specificity, but differences between avian breeds exist and have to be reckoned with.