THE EFFECTS OF HISTAMINE AND OTHER NATURALLY OCCURRING IMIDAZOLES ON NEURONES OF HELIX ASPERSA

Abstract

There is at present but little evidence to suggest that histamine has the role of a transmitter substance in either the vertebrate or the invertebrate central nervous system. Few studies have, however, been made of the actions of histamine on the central nervous system and those results that have been reported have often been obtained by indirect methods. Furthermore there is still a great deal to be learnt about the nature of the central receptors for histamine.The isolated brain of the snail Helix aspersa is a convenient central nervous system preparation for studying the actions of substances at the cellular level because it contains many large cells, from 80 to 150 [t in diameter, which can be penetrated with microelectrodes. Furthermore, the cells are placed superficially and so allow easy access for drug application. Kerkut & Walker (1962) investigated the actions of a range of chemical substances on single neurones in the snail brain and found that some of the cells responded to histamine. The experiments described in the present paper were undertaken to investigate the possibility that histamine is a transmitter substance in the invertebrate central nervous system and also to obtain information on the broader question of the general nature of histamine receptors in nervous tissue.Some of these results were reported to the meeting of the British Pharmacological Society held at Nottingham in January, 1967. METHODSThe experiments were performed on isolated circumoesophageal ganglionic masses from garden snails, Helix aspersa, which were collected locally. The shell was removed, the animal pinned out and the brain was exposed. The connective tissue covering the brain was removed and the brain was attached to a glass microscope slide with two rubber bands. The whole preparation was immersed in a 20 ml. bath containing snail Ringer solution. The snail Ringer contained (mM): KC1 4; NaCl, 80; CaCl2, 7; MgCl2, 5; Tris HCl, 5. The pH of the Ringer was 8.0.Glass microelectrodes were pulled on a Palmer microelectrode puller and filled with M potassium acetate, or in some experiments, with M potassium chloride. The recording electrodes had a resistance of from 5 to 30 MQ and a tip diameter of less than 0.5 As.

Histamine as a Neuroregulator

“…The excitatory response was blocked by pyrilamine (0.2 mM), and the inhibitory by metiamide (0.2 mM) (Gotow et aI 1980a,b). In the absence of known histamine-specific circuits, follower cells, or synapses, the physiological relevance of these findings and those of others on various species is not clear (Kerkut et al 1968, Carpenter & Gaubatz 1975, Takecuchi et al 1976, Ku & Takeuchi 1983). Some evidence suggests that the latter response is mediated by cyclic nucleotides (Gotow & Hashimura 1982).…”

Νευροχημική Και Νευροβιολογική Μελέτη Της Επίδρασης Του Εμπλουτισμένου Περιβάλλοντος Στη Φυσιολογία Της Όρασης Των Επιμύων

“…Ζ ελεξγνπνίεζε ησλ ηζηακηλεξγηθψλ λεπξψλσλ πνηθίιιεη θαηά ηε δηάξθεηα ηνπ θχθινπ χπλνπ-αθχπληζεο, είλαη εληνλφηεξε θαηά ηε θάζε ηεο εγξήγνξζεο, κεηψλεηαη θαηά ηνλ χπλν βξαδέσλ θπκάησλ θαη εμαθαλίδεηαη θαηά ηνλ χπλν REM (Monti 1993). Δπηπιένλ, ε απειεπζέξσζε ηζηακίλεο παξνπζηάδεη αληίζηνηρν θηξθάδην ξπζκφ (Kerkut, Walker et al 1968;Mochizuki, Yamatodani et al 1992). Πηζαλφηαηα πεξηνρέο κε ππθλή λεχξσζε ή πνιπάξηζκνπο ππνδνρείο, φπσο ν ππνζάιακνο, δηεγείξνληαη ζπλερψο θαηά ην ζηάδην εγξήγνξζεο, ελψ πεξηνρέο κε ρακειφηεξε ππθλφηεηα λεχξσζεο ή ππνδνρέσλ, φπσο ν ηππφθακπνο θαη ην εγθεθαιηθφ ζηέιερνο, δηεγείξνληαη θάησ απφ ζπγθεθξηκέλεο αθξαίεο θαηαζηάζεηο, νπφηε νη ηζηακηλεξγηθνί λεπξψλεο ελεξγνπνηνχληαη κε απμεκέλε ηαρχηεηα (Brown, Stevens et al 2001 (Nawrocki, Nowak et al 1985;Nowak 1985;Nowak, Nawrocki et al 1985).…”