GAS CHROMATOGRAPHIC–MASS SPECTROMETRIC ANALYSIS OF BIOGENIC AMINES IN IDENTIFIED NEURONS AND TISSUES OF HIRUDO MEDICINALIS

—Previous workers have reported that the colossal cells of Retzius in the segmental ganglia of the medicinal leech contain about 2.3 pmol of 5‐hydroxytryptamme (5‐HT)/cell body. We verify the identify of 5‐HT in the Retzius cells by gas chromatography‐mass spectrometry and derive concentrations of 1.3–4.1 pmol/neuron by analyses of eight individually dissected Retzius cell bodies. The Retzius cell bodies contain about 30% of the 5‐HT in each ganglion. An average of 25 pmol 5‐HT/mg tissue, a concentration about 500 times lower than that in the Retzius cell, was found in the fibrous, pigmented tissue surrounding the leech nervous system. We could not detect γ‐aminobutyric acid, octopamine, dopamine or norepinephrine in the Retzius cells, in the pigmented tissue, or, with the possible exception of dopamine (±0.4 pmol/ganglion), in whole ganglia. Furthermore, we could not detect 5‐HT in pooled samples of 100 non‐chromaffin control neurons.