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Title of Thesis

Nasreen Akhtar
Institute/University/Department Details
University of Karachi/ Department of Physiology
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
hypothalamo-neurohypophyseal system, rana cyanophlyotis, bufo melanosticus, neurosecretory cells, hydrolysates, oxytocic activities, vasopressor activities, mesotocin, arginine vasopressin, arginine vasotocin

Hypothalamo-neurohypophyseal system in two amphibian species –Rana cyanophlyotis and Bufo melanostieus is described. Cytomorphology of the neurosecretory cells in nucleus preopticus is similar to that described for other amphibian species. A majority of neurosecretory cells are unipolar. A few cells are however, bipolar. The cells of nucleus preopticus are disposed off in dorsal and ventral groups. No axonal flow of aldehyde fuehsin positive neurosecretory material could be traced into the third ventricle under normal conditions. Cyclical changes in the content of aldehyde fuchsin positive material in R. cyanophlyctis reveal highest fuchsinophilia in the months of May and July. The cyclical changes seem to correspond with the reproductive phases of the animal. Whereas it is possible to find two morphological types of aldehyde fuhsin positive granules in B. melanosticus, only one type oxists in R. cyanophlyctis. Two morphological types of granules have however, been found in cyanophlyctis under certain experimental conditions

Effects of dehydration, salination, inanition and injections of oxytocin, vasopressin and adrenaline have been studied in each species in an identical experimental design. Dehydration, salination, inanition and adrenaline depletes the neureseeretory material in the nucleus preopticus

The extent of funchsinophilia is increased with oxytocin. This affects both the dorsal and ventral groups of neurons. There is aittle change if any in vasopressin injected animals. Bioassayable oxytocic and vasopressor activities as recorded in the normal animals are of the order of 24.2+1.15 mu/mg and 31.4+1.75mu/mg and 69.0 _2.7mu/mg respectively in B.melanosticus. Under experimental conditions similar to those employed for cytomorphological investigations, oxytocic activity in salinated and vasopressin treated animals increases, but is reduced to 6.4+1.05 mu/mg in dhydrated animals. There is tittle change in the oxytocic activity in oxytocin treated animals as compared to the normal. The vasopressor activity increases in salinated animals, remains unchanges in vasopressin in injected and dehydrated animals and is deplated in oxytocin treated animals. It has been suggested that assayable activity in the neurointermediate lobe is coincident partly with the increase or decrease of funchsinophilia in the nucleus preopticus. Residual oxytocic activity in dehyindicate the presence of arginine vasopressin, arginine vasotocin and mesotocin. The bioassay data for B. melanosticus under identical experimental conditions has been similarly interpreted and the presence of arginine vasopressin and arginine vasotocin has been suggested. A slow quantal release from neurointermediate lobe, depending upon the circulating levels of these peptides seems to be operative at the level of the neurointermediate lobe

Hypothalamic peptides isolated by papert chromatography have been characterized chemically and pharmacologically. Arginine vasopressin and arginine vasotocin are present in both the species. Mesotocin is present only in R. cyanophylctis. Certain peptides with pressor/oxytocic activity or without any activity have been located. That arginine vasotocin exists in at least three polymorphic forms in the two species is indicated from the data obtained. The microheteergenity described is on the chemical rather than pharmacological level. A possible evolution of these hormonal principles is discussed

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
293.92 KB
2 1 Introduction 4
185.59 KB
3 2 Materials And Methods 11
177.72 KB
  2.1 Animals 11
  2.2 Histological Procedure 11
  2.3 Experimental Animals 13
  2.4 Preparation Of Neurointermediate Lobe 14
  2.5 Extract For Bioassays Preparation Of The Extract For Chromatographic Separation 14
  2.6 Chromatographic Separation 15
  2.7 Chromatography Of The Hydrolysates Of Eluted Bands 17
  2.8 Bioassays 18
4 3 Results 21
1214.15 KB
  3.1 Hypothalamo-Neurohypophseal Of Rana Cyanophlyctis 21
  3.2 Changes In The Hypothalamic Neurosecretion Under Various Experimental Conditions 29
  3.3 Bioassay Of Oxytocic And Vasopressor Activities In The Posterior Lobe Of Experimental Animals 41
  3.4 Chemical And Pharmacological Characterization Of The Hypothalamic Neurosecretions In Rana Cyanophlyctis 45
  3.5 Hypothalamo-Neurohypophyseal System Of Bufo Melanosticus 57
  3.6 Cahnges In The Hypothalamic Neurosacretions Under Various Experimental Conditions 61
  3.7 Bioassay Of Oxytocic And Vasopressor Activities In The Posterior Lobes Of Experimental Animals 71
  3.8 Chemical And Pharmacological Characterization Of Hypothalamic Neurosecretions In Bufo Melanosticus 76
5 4 Discussion 86
724.38 KB
  4.1 Evolution Of The Neurohypophyseal Hormones 101
  4.2 Summary And Concluslions 106
  4.3 References 109
6 5 References Cited In Chapter- Evolution Of Neurohyphyseal Hormones 126
27.89 KB
  5.1 Vita 127