The visual system of the fruit fly is ideal for studying the association between neurons and glia. These interact during the morphogenesis of brain neuropiles and, in the adult, work together to maintain an ideal environment for neuronal function. In this thesis I characterise the pupal metamorphosis and adult structure of glia in the optic lobe’s lamina and medulla neuropiles. Photoreceptor axons from the fly’s compound eyes terminate at locations within these neuropiles that allow them intimate contact with glia. Some neuropile glia take up and inactivate the neurotransmitter histamine after its release at photoreceptor synapses. A shuttle pathway between the glia and photoreceptors then transports inactivated histamine back to photoreceptors for reuse. The gene CG12120 encodes the protein Tan, which liberates recycled histamine within the photoreceptor cytoplasm, it is then pumped into vesicles for re-release. Histamine, however, is not exclusive to the visual system. A system of glial barriers in the lamina, and around the brain, controls the movement of histamine between neuropiles as well as between the body and the brain. How histamine is reciprocally transported between photoreceptors and glia remains unknown despite attempts to uncover candidate transporters. Photoreceptor-specific capitate projections form as invaginations from neuropile glia into photoreceptor terminals. The transmitter needs of the photoreceptor appear to dictate the dynamic structure of capitate projections, which change in shape and number after perturbations that affect terminal location, synapse number or histamine release at the photoreceptor. This dynamism suggests that capitate projections play an important role, not only in recycling synaptic vesicles, but also in recycling histamine.

Thesis (doctoral)--Freie Universität Berlin, 1979.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Cycloalkyl analogues of Antergan with the basic structure of N, N-dimethyl-N’-cycloalkylmethyl-N’-phenylethylenedi-amlne have been synthesized in good yields. The alkyl group was a butyl-, pentyl-, hexyl-, or heptyl-ring structure. The compounds with the benzyl group of Antergan substituted by a hydrogen or a methyl group were also synthesized in good yields. The general reaction sequence followed was to start with the appropriate cycloalkanecarboxyllc acid and build up to a secondary amine via an acid chloride and an amide. Leung’s methods (1) were followed and checked up to this step. Further reaction sequences were developed during this study. The desired amine was reacted with chloroacetyl chloride, dimethylamine and then reduced to the tertiary diamine analogues. The preliminary antihistamine activity of these analogues was studied and compared with that of Diphenhydramine Hydrochloride Standard Solution. The relative activity of each analogue was also determined. / Pharmaceutical Sciences, Faculty of / Graduate

In order to characterize the types of histamine receptors (H₁ or H₂) in rabbit atria, isolated atrial preparations were exposed to selective histamine receptor agonists, alone and in the presence of selective histamine receptor antagonists. The rate of isolated right atria was increased by histamine (H₁ and H₂), 4-methylhistamine (H₂), and impromidine (H₂). 2-Pyridylethylamine (PEA, H₁) had very little effect on atrial rate. Cimetidine pretreatment (selective H₂ receptor blockade) competitively antagonized the positive chronotropic effects of histamine, 4-methylhistamine, and impromidine. Promethazine pretreatment (selective H₁ receptor blockade) competitively blocked the chronotropic effects of histamine, but had no effect on the responses to 4-methylhistamine or impromidine. The force of isolated left atria was increased by all four agonists. Cimetidine pretreatment competitively blocked the inotropic effects of histamine, 4-methylhistamine, and impromidine, and had no effect on the response to PEA. Promethazine pretreatment competitively blocked the inotropic responses to histamine and to PEA, and had no effect on the responses to 4-methylhistamine or impromidine. The phosphodiesterase inhibitor theophylline (3 x 10⁻⁴M) potentiated the inotropic but not the chronotropic effects of 4-methylhistamine. (1 x 10⁻⁴M , impromidine (1 x 10⁻⁸M) and PEA (1 x 10⁻⁴M) . Histamine (1 x 10⁻⁵M) exposure for 20 seconds did not alter the cyclic AMP levels of isolated rabbit right and left atria. We report that both types (H₁ and H₂) of histamine receptors are present in rabbit right and left atria. However, I cannot confirm reports (Hughes,1978) that both H₁ and H₂ histamine receptor agonists act through the generation of cyclic AMP. / Pharmaceutical Sciences, Faculty of / Graduate

No description available.

Call number: LD2668 .T4 1961 B88

Call number: LD2668 .T4 1961 B89

Call number: LD2668 .T4 1961 R68

published_or_final_version / Pharmacology / Master / Master of Philosophy