THE ACTION OF PROGESTATIONAL AGENTS ON OXYTOCINASE ACTIVITY IN THE FEMALE RABBIT HYPOTHALAMUS

1972 ◽  
Vol 70 (3) ◽  
pp. 429-437
Author(s):  
Dona A. Frith ◽  
K. C. Hooper
Keyword(s):  
Enzyme Activity ◽  
Hormone Secretion ◽  
Female Rabbit ◽  
Activity Of Enzymes ◽  
Dose Levels

ABSTRACT Female rabbits were injected with progesterone, 20α-hydroxy-pregn-4-en-3-one (20α-OH) and 20β-hydroxy-pregn-4-en-3-one (20β-OH), and the effects of these progestogens on the activity of enzymes in the hypothalamus were noted. 20α-OH produced a significant decrease in enzyme activity whereas 20β-OH did not. It is suggested therefore that 20α-OH is responsible for the depression in enzyme activity which occurs in the female rabbit after coitus (Frith & Hooper 1971a). Progesterone, at different dose levels, produced effects on enzyme activity which can be correlated with the known pattern of gonadotrophic hormone secretion. The results substantiate the hypothesis proposed by the authors that there is a relationship between enzyme levels in the hypothalamus and gonadotrophic hormone secretion.

THE ACTION OF SOME OVULATION INHIBITORS ON THE RABBIT HYPOTHALAMUS

1971 ◽  
Vol 66 (2) ◽  
pp. 221-228 ◽  
Author(s):  
Dona A. Frith ◽  
K. C. Hooper
Keyword(s):  
Enzyme Activity ◽  
Hormone Secretion ◽  
Chlormadinone Acetate ◽  
Releasing Factors ◽  
Sites Of Action ◽  
Ethinyl Oestradiol

ABSTRACT The previous paper (Frith & Hooper 1971) described the activities of certain hypothalamic enzymes at various times after mating and it was suggested that changes in enzymes levels may be used as an index of the release of gonadotrophic hormones. Using this approach, a study has been made of the action of the ovulation inhibitors chlormadinone acetate, norethindrone, ethinyl oestradiol and oestrone on the rabbit hypothalamus. The four inhibitors increased enzyme activity in the hypothalamus. Previous work has shown that raised levels of enzyme activity are associated with a lowered level of gonadotrophic hormone secretion. It is suggested, therefore, that one of the sites of action of the inhibitors is on polypeptide turnover in the hypothalamus, and it seems possible that this is one of the factors controlling the availability of gonadotrophin releasing factors.

scholarly journals Influence of fullerenol C60(OH)24 on enzime status in serum of rats after single dose administration of doxorubicine

2008 ◽  
Vol 62 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Biljana Govedarica ◽  
Vukosava Djordjevic-Milic ◽  
Natasa Radic ◽  
Branislava Srdjenovic ◽  
Aleksandar Djordjevic
Keyword(s):  
Enzyme Activity ◽  
Single Dose ◽  
Free Radicals ◽  
Side Effects ◽  
Topoisomerase Ii ◽  
Control Group ◽  
Limiting Factor ◽  
Dose Administration ◽  
Activity Of Enzymes

The antracycline antibiotics have one of the widest areas of use in oncology. The most investigated mechanisms of their antineoplastic activity include: interactions of these antibiotics with DNA, inhibition of topoisomerase II and production of free radicals. However, the side effects of doxorubicin, especially cardiotoxicity, are the limiting factor of its use in cancer therapy. The aim of this research was to investigate the influence of fullerenol ?60(?H)24 as a cytoprotector in single doze administration of doxorubicin on the activity of enzymes in serum (CK, AST, ALT, LDH and a-HBDH) in rats in in vivo system. Activity of enzymes (CK, LDH, HBDH, AST, and ALT) in serume was measured with standard commercial methods. The results of analysis of the samples treated with the combination of fullerenol and doxorubicin show no difference in enzyme activity in comparison with the control group. The results indicate the possibility of using fullerenol as a protector in the therapy with doxorubicin in malign neoplasm.

THE ACTIVITY OF ENZYMES IN THE RABBIT UTERUS AND EFFECT OF PROGESTERONE AND OESTRADIOL

1969 ◽  
Vol 43 (2) ◽  
pp. 167-174 ◽  
Author(s):  
R. N. MURDOCH ◽  
I. G. WHITE
Keyword(s):  
Alkaline Phosphatase ◽  
Enzyme Activity ◽  
Succinic Dehydrogenase ◽  
Lactic Dehydrogenase ◽  
Glutamate Oxaloacetate Transaminase ◽  
Oestrogen Treatment ◽  
Uterine Endometrium ◽  
Uterine Fluid ◽  
Activity Of Enzymes ◽  
Glucose 6 Phosphate Dehydrogenase

SUMMARY The activity of several enzymes has been measured in the uterine endometrium of the rabbit during oestrus and pseudopregnancy and after injecting oestradiol benzoate or progesterone 28 days after ovariectomy. The enzyme activity of the uterine fluid has been determined during oestrus and the effect of uterine ligation studied. Progesterone and the induction of pseudopregnancy stimulated succinic dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (GDH) activity and depressed amylase and lactic dehydrogenase (LDH) activity. In ovariectomized does, glutamate-oxaloacetate transaminase (GOT) activity increased after the injection of progesterone. Progesterone also stimulated endometrial phosphatase after ovariectomy but, when given after a period of oestrogen treatment, it limited the even greater response of acid and alkaline phosphatase to oestrogen; the activity then attaining the same level as when progesterone alone was given. SDH, GDH and glycerylphosphorylcholine (GPC) diesterase could not be detected in uterine fluid but amylase and alkaline phosphatase were in greater concentration than in the endometrium. GPC diesterase was, however, found to be present in uterine tissue. Ligation of the uterus did not significantly alter the enzyme activity of the endometrium.

THE EFFECT OF MATING ON PITUITARY LUTEINIZING HORMONE AND THYROTROPHIC HORMONE CONTENT IN THE FEMALE RABBIT

1968 ◽  
Vol 41 (1) ◽  
pp. 91-94 ◽  
Author(s):  
K. BROWN-GRANT ◽  
D. J. EL KABIR ◽  
G. FINK
Keyword(s):  
Luteinizing Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Female Rabbit ◽  
Hormone Content ◽  
Thyrotrophic Hormone

SUMMARY The anterior pituitary content of luteinizing hormone (LH) was greatly reduced 4 hr. after mating in female rabbits; thyrotrophic hormone content was slightly but not significantly reduced. At 24 hr. after mating LH levels were higher than those at 4 hr. but still significantly below control levels; thyrotrophic hormone content was significantly reduced at this time. Since no evidence is available of an increase in thyrotrophic hormone secretion after mating (see Brown-Grant, 1968) it is concluded that the neuroendocrine events concerned in the release of LH in response to coitus in this species also result in a decrease in the synthesis of thyrotrophic hormone.

Opioidergic control of luteinizing hormone secretion in the female rabbit: influence of age on the response to naloxone

1988 ◽  
Vol 66 (1) ◽  
pp. 38-42 ◽  
Author(s):  
E. V. YoungLai ◽  
M. Wilkinson ◽  
N. Thompson ◽  
A. Byrne
Keyword(s):  
Luteinizing Hormone ◽  
Hormone Secretion ◽  
Elevated Serum ◽  
Luteinizing Hormone Secretion ◽  
Serum Progesterone ◽  
Female Rabbit ◽  
Lh Release ◽  
Lh Secretion ◽  
Normal Inhibition

To examine the role of opioid neurons on luteinizing hormone (LH) secretion in the female rabbit, we determined LH release at timed intervals after naloxone administration to rabbits aged 25–150 days. The LH response to naloxone (10 mg/kg) was not significantly elevated until day 43 when LH rose 76–113% above basal levels at 40–80 min. In 56-day-old females the corresponding increase was 160% at 15 min and in 65- to 67-day-olds it was 154%. From 70 to 80 days of age the LH response was blunted and no significant elevations could be elicited. By contrast, naloxone-induced LH increases were again evident when rabbits were older than 100 days. At all ages no significant change in FSH concentrations was observed. In the adult females, naloxone at 2.5, 5, and 10 mg/kg caused increases in LH secretion which occasionally were high enough to induce ovulation as exemplified by elevated serum progesterone 4 days later. These data suggest that opioid peptides may be involved in the prepubertal rise in LH and in the normal inhibition of adult secretion in the female rabbit.

Corticosterone does not cause Testicular Toxicopathology in the Rat: Relevance to Methylxanthines, ACTH and Stress

1992 ◽  
Vol 11 (6) ◽  
pp. 505-509 ◽  
Author(s):  
P.W. Harvey ◽  
J. Er ◽  
C. Fernandes ◽  
K.C. Rush ◽  
I.R. Major ◽  
...  
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Body Weight Gain ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Male Rats ◽  
Reduced Body ◽  
Relevant Dose ◽  
Dose Levels ◽  
Adrenocortical System

1 Methylxanthines, ACTH and stress are well known to produce testicular pathology (e.g. seminiferous tubule atrophy). Methylxanthines, ACTH and stress alter hormone secretion, particularly from the pituitary-adrenocortical system. Consequently, it has recently been suggested that there may be a causal relationship between changes in endogenous physiological adrenocortical secretions, particularly corticosterone, and testicular pathology.1 2 This study tested the hypothesis that corticosterone mediates the testicular effects of both methylxanthine treatment and stress. Corticosterone was administered daily by subcutaneous injection to groups of 10 male rats at dose levels of 2 or 20 mg kg-1 in propylene glycol (1 ml kg-1) for 1 month (the shortest duration of methylxanthine or ACTH exposure known to produce testicular pathology). The highest dose of corticosterone resulted in plasma concentrations that closely matched values resulting from stress (200-700 ng ml-1) compared with controls (<25 ng ml-1). 3 The highest dose of corticosterone caused reduced body weight gain, lower thymus, adrenal, seminal vesicle and prostate weights, but did not induce any testicular pathology. 4 That a high, but physiologically relevant, dose of corticosterone did not cause testicular pathology in this experiment excludes this steroid in the direct aetiology of methylxanthine, ACTH and stress-induced testicular pathology. Other steroids secreted from the adrenal, in combination with corticosterone, may be involved.

scholarly journals A RAPID METHOD FOR THE DETERMINATION OF PROTEOLYTIC ACTIVITIES OF ENZYME PREPARATIONS

1948 ◽  
Vol 32 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Bacon F. Chow ◽  
Mary-Ann Peticolas
Keyword(s):  
Enzyme Activity ◽  
Trichloroacetic Acid ◽  
Enzyme Concentration ◽  
Cent Solution ◽  
Enzyme Preparations ◽  
Proteolytic Activities ◽  
Activity Of Enzymes ◽  
Different Sources ◽  
Rate Of Activation

A method has been described for the determination of proteolytic activities of enzyme preparations using casein as substrate. The rate of digestion is proportional to the enzyme concentration used. This relationship is utilized as a measure of the enzyme activity. One unit of activity is defined as the amount which is required to digest casein in 15 minutes at 37.5°C. so that 50 per cent of the protein in 1 ml. of 0.25 per cent solution is not precipitable by trichloroacetic acid. This method has been used to determine the activity of enzymes from different sources and also used to follow the rate of activation of enzymes.

scholarly journals Effects of WY-14643 on Peroxisomal Enzyme Activity and Hormone Secretion in Immortalized Human Trophoblast Cells

2009 ◽  
Vol 32 (7) ◽  
pp. 1278-1282
Author(s):  
Fumie Hashimoto ◽  
Mieko Morita ◽  
Kaori Iwasaki ◽  
Satoru Takeda ◽  
Hidenori Hayashi
Keyword(s):  
Enzyme Activity ◽  
Hormone Secretion ◽  
Trophoblast Cells ◽  
Peroxisomal Enzyme ◽  
Human Trophoblast ◽  
Human Trophoblast Cells

scholarly journals Characteristics and mechanism of a novel chitinase mutant from Trichoderma harzianum with enhanced activity

2019 ◽  
Author(s):  
Xinfeng Chai ◽  
Jiahuang Li ◽  
Jiayin Liu ◽  
Xiuling Chen ◽  
Wei Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Trichoderma Harzianum ◽  
Structural Model ◽  
Docking Analysis ◽  
High Enzyme ◽  
Activity Of Enzymes ◽  
Pcr Method ◽  
Binding Residues ◽  
Key Residues ◽  
Insight Into

Abstract Background: Chitinase from Trichoderma harzianum could inhibit various chitin-containing pathogens. In this study, a mutant of Chit42 (Chit42m) with high enzyme activity was established by error-prone PCR method. Results: The Chit42m with three amino acids substitutions (D100G/I166V/A382P) was obtained from 1230 colonies. The activity of the Chit42m was enhanced by 1.26 times and affinity increased by 3.2 folds. The Chit42m showed the optimum temperature was 50 °C and pH 7.5. Conclusion: Structural model and molecular docking analysis suggested that A382P may affect the catalytic activity of enzymes by affecting the conformation of key residues D169 and E171 related to catalysis, while I166V probably affects the affinity of chitin and enzymes by influencing the conformation of important substrate binding residues R52 and Y293. D100G had little effect on the changes of enzyme activity. This would put insight into the study of the site-specific mutations and provide promising gene material for the directed evolution chitinase.

scholarly journals Root growth and antioxidant enzyme responses to aluminium stress in sugarcane

2020 ◽  
Vol 41 (6supl2) ◽  
pp. 3449-3456
Author(s):  
Lucas Smith Pimenta ◽  
◽  
Eduardo Dal’Ava Mariano ◽  
Rodrigo Gazaffi ◽  
Monalisa Sampaio Carneiro ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Enzyme Activity ◽  
Root Growth ◽  
Screening Method ◽  
Acid Soils ◽  
Al Toxicity ◽  
Plant Production ◽  
Hydroponic System ◽  
Tropical Regions ◽  
Activity Of Enzymes

Aluminium (Al) toxicity in acid soils is a major abiotic stress that can limit plant production worldwide. Al toxicity directly inhibits root development and exacerbates oxidative stress in the plant. Sugarcane is mostly cultivated in tropical regions and is often exposed to phytotoxic concentrations of soil Al. In this study, our objectives were to evaluate nine sugarcane cultivars on their tolerance to Al in a hydroponic system, investigating the effects of 143µM {Al3+} on root growth and on activity of the antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD). The screening method proposed was suitable for a rapid, reliable and reproducible procedure of the sugarcane cultivars. Exposure to Al for three days altered root growth and activity of enzymes of the nine sugarcane cultivars. However, the magnitude of the alterations varied significantly among cultivars. The cultivar RB928064 was classified as Al-tolerant and the cultivar RB835486 as Al-sensitive. Increases in enzyme activity after Al exposure varied from 4 to 46%, with average increases of 19% in APX, 20% in CAT, and 8% in SOD. The variations induced by Al in enzyme activity, however, did not correlate significantly with those variations induced by Al in the root growth.

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