The evaluation of melatonin as a possible antidepressive
- Authors: Skene, Debra Jean
- Date: 1980
- Subjects: Melatonin , Antidepressants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3728 , http://hdl.handle.net/10962/d1001465
- Description: Melatonin, a hormone of the pineal gland, was evaluated in a variety of animal models of depression. Measurements of the frog righting reflex and rat locomotor activity showed that low doses of melatonin have a serotonin-like potentiating effect following monoamine oxidase inhibition. High doses of melatonin caused a reduction in the duration of rat immobility in the Porsolt model of depression and exerted a chlorpromazine-like effect on conditioned avoidance behaviour. In view of the indoleamine hypothesis of depressive disorders, the possibility of melatonin being a potential antidepressive is discussed and it is concluded that melatonin might be useful in the treatment of "agitated" depressions
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- Date Issued: 1980
Adreno-active substances and the pineal gland
- Authors: Midlane, Graham Wallace
- Date: 1979
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3738 , http://hdl.handle.net/10962/d1001530
- Description: The pineal gland, a biochemically very active neuroendocrine transducer which is innervated by the sympathetic nervous system, was used in vivo to evaluate the effect of different þ-adrenoceptor agonists and antagonists on pineal enzyme levels. Hydroxyindole-O-methyltransferase (HIOMT), an enzyme with a circadian activity and unknown control was not significantly affected by these drugs. The activity of serotonin N-acetyltransferase, another pineal enzyme with a greater amplitude of circadian rhythmicity and which is under noradrenergic neural control, the degree of blockade depending on the selectivity and affinity of the agent used. An attempt was also made to alter the oestrous cycle of the rat by dosing with þ-active substances. Only propranolol had any effect on the oestrous cycle. It was not possible to establish an absolute link between the alteration in pineal enzyme activity and an influence on the oestrous cycle. It was concluded that the pineal enzyme studies are useful pharmacological means for evaluating þ-active substances
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- Date Issued: 1979
Secondary effects of oral contraceptives
- Authors: Yuen, E Ho
- Date: 1978
- Subjects: Oral contraceptives , Oral contraceptives -- Side effects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3847 , http://hdl.handle.net/10962/d1012296
- Description: Norethynodrel, a common progestin in oral contraceptives, produces in female rats several significant physiological, cytological and biochemical changes at dose levels of 1 mg and 20 mg per kg: 1) a relative increase in liver mass 2) modification of appearance and extent of the endoplasmic reticulum 3) augmentation of the protein content of the liver 4) increase of the level of cytochrome P- 450 in the liver as determined by : a) difference spectroscopy b) increases in biotransformation of aniline and aminopyrine in vitro and c) reduction of sleeping times of rats dosed with phenobarbital The significance of these findings becomes evident when it is realized that norethynodrel affects and is affected by the same enzyme system which oxidizes medicaments in general in the body: induction of cytochrome P-450 by administration of norethynodrel may interfere with the action of other drugs . Ethinyl estradiol alone showed none of the inductive effects. At high dose levels (20 mg per kg) both norethynodrel and ethinyl estradiol caused a marked inhibition of growth of the animals, producing a net loss of body mass over the 30- day experimental period. Electron micrographic evidence implies that there is also a lowering of glycogen content and a chemical change in the lipids of adrenocortical and liver cells accompanying the use of these agents.
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- Date Issued: 1978