The fine structure of the retinula of the compound eye of Astacus fluviatilis

Summary Intraventricular injections of moderate doses (25–75g) of 5,7-dihydroxytryptamine (5,7-DHT) into the left lateral ventricle of ether anaesthetized rats cause pronounced damage to CNS indoleamine axons, reflected by accumulations of large amounts of serotonin in distorted, heavily swollen axons, so called indoleamine droplet fibres. Larger doses (100, 150 or 300 g) provoke a piling up of catecholamines in drug affected preterminal catecholamine containing fibres besides extensive lesioning of indoleamine axons.5,7-DHT condenses with formaldehyde to form a light yellow fluorescent compound. Uptake and accumulation of 5,7-DHT into indoleamine terminals and axons—as revealed in short term experiments—provides a means of mapping of indoleamine neurons in the rat brain.Following the application of 5,7-DHT (25–150 g), rats develop characteristic behavioural disturbances, as e.g. increased sensitivity to sensory stimulation, and a failure to habituate to repeatedly applied sensory stimuli, and bizarre social behaviour, i.e. repeated fighting attacks in an unusual upright posture. These alterations resemble those observed after 5,6-DHT and may be indicative of a deprivation of the brain from functional serotonin.5,7-DHT is considered to be an important, additional tool for the investigation of serotonin neurons and problems of serotonin transmission in the mammalian brain.Dedicated to Prof. Dr. Dr. R. Janzen with the best wishes for his 65th birthday.Supported by the Deutsche Forschungsgemeinschaft.