I= MAJOR STUDIES ON THE STRUCTURE, CIRCULATORY PATTERNS AND FUNCTIONAL ROLE OF THYROID, ENDOCRINE PANCREAS AND PARATHYROID GLANDS DURING DIFFERING AGE AND REPRODUCTIVE PHASES OF DWARF GOAT
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Title of Thesis
MAJOR STUDIES ON THE STRUCTURE, CIRCULATORY PATTERNS AND FUNCTIONAL ROLE OF THYROID, ENDOCRINE PANCREAS AND PARATHYROID GLANDS DURING DIFFERING AGE AND REPRODUCTIVE PHASES OF DWARF GOAT

Author(s)
Anwarul Islam
Institute/University/Department Details
Department of Zoology, University of the Punjab, Lahore
Session
1993
Subject
Zoology
Number of Pages
342
Keywords (Extracted from title, table of contents and abstract of thesis)
thyroid, endocrine pancreas, parathyroid glands, dwarf goat, thyroidal lobe, tsh, t3, t4, thyroid gland

Abstract
The functional aspects of thyroid, endocrine pancreas and parathyroid glands in differing age and reproductive states of dwarf goat were studied while observing their structure at differing age and circulatory pattern of the hormones in normal and experimentally altered conditions.

Estrumate (125 µg cloprostenol/head) synchronized females exhibited 19.79 ± 0.67 days estrous and 148.11 ± 0.81 days gestation length. Increase in body weight during pregnancy and drop following parturition was correlated with the number of fetuses. Male kids had; greater birth weight, better survival and fast growth.

Right thyroidal lobe is morphologically less developed than left one with increasing follicular and reducing epithelial cell size with advancing age.

Markedly elected TSH eight hours postnatal was restored to birth level on second day with gradual increase up to fifteenth day, thereafter reduced on sixth weed and without further change up to three months of age. Except a rise at 40th hour and between 5th to 15th day in T3 and an elevation in T3:T4 ratio on the second day, both of THs and their ratio showed consistent reduction after birth to three months of age. The results expound that peripheral metabolism was established postnatally on the second day with stimulated pace up to 5th day however at lower magnitude afterwards.

THS and thyroxine both increased around estrus and decreased during early diestrus, later only TSH decreased T3 reduced at estrus, increased during metestrus in PGF2α synchronized cycle but reduced in natural cycle, however, increased during diestrus in both category of the cycles. Changes in plasmatic T3 resembled with T3:T4 ratio during different phases of the cycle. Plasma TSH and T4 decreased with unaltered T3 and increased T3:T4 ratio after conception. T4 and T3 both did not change but TSH increased and T3:T4 ratio decreased up to about 50 day of gestation. TSH did not change while THs and their ratio increased during late phase of mid pregnancy. TSH was decreased to its nadir while oppositely THs and their ratio increased to their highest concentration around 100 days gestation. Thereafter, TSH remained unaltered a week prepartum; whereas thyroid hormones and their ratio decreased continuously till parturition. Reduced TSH after kidding, was rehabilitated in a week and remained unaltered during the 1st month but reduced during the 2nd and 3rd month of lactation. T4 and T3 level increased up to mid and reduced afterwards in late lactation. T3:T4 ratio did not vary from T3 pattern throughout lactation except an abrupt elevation during the first week.

Exogenous TRH enhanced TSH and PRL release effectively with no effect on GH Plasmatic TSH increased maximally, thirty minutes after 3 µg/kg and at an hour after 18 µg/kg and at an hour after 18 µg/kg, whereas PRL fifteen minutes after 3amd 18 µg/kg and an hour after 9 µg/kg. thereafter, both hormones decreased up to three hours in all groups T4 and T3 elevated regularly up to three hours in all three groups. T3:T4 ratio increased after TRH but independently to the doses. TSH administration (0.5 µg/kg) enhanced THs to their extreme level two hours after, which reduced almost to pretest level at 24th hour. T3:T4 ratio increased more in TSH infected group than control bucks.

After ten days of Bt4 and Bt3 administrations (200 µg/kg/day) hemoglobin level was greater in T4 treated group only but in T3 group too after 20 days of the treatments. Plasmatic levels of total and different fractions of lipids lessened and glucose increased during the treatment period and recovered after the withdrawal of the treatments. During IVGTT, glucose utilization was prompt in THs treated goats, because of enhanced secretion of insulin.

Triangular shaped stratified pancreas had two type of islets; insulin dominant islets were in abundance near the liver and glucagon dominant near duodenum or mid part of the pancreas Ÿ-cell averaged at about 40% and α-cell about 15% of total cell population without age related change.

Glucose and insulin at 16th hour after birth were noticeably greater than their levels just after birth. Birth level of glucose was restored on first day but insulin and glucagon on third day. Afterwards, glucagon reduced up to three weeks then increased sharply up to 12 weeks. Insulin and glucose both were increased for 15 days later kept on decreasing up to twelve weeds of age.

Plasma glucose increased without variation in glucagon and insulin around estrus. However, insulin exhibited a pulsatile increase in early diestrus and glucagon reduced in late diestrus. Glucose and glucagon were reduced and insulin increased after conception. Later elevated insulin level remained unaltered for ninety days, it enhanced further to a peak around 105 days and reduced afterwards but elevated consistently near parturition. Glucose level fluctuated for the 100 days of gestation but reduced during late pregnancy and increased before parturition. Glucagon increased steeply throughout gestation which decreased near parturition and was restored in a week of lactation. Glucose and glucagon reduced and insulin increased consistently with advancing lactation.

Absorption of orally loaded glucose (1.0 g/kg) and subsequently its clearance was quicker in kids, lactating and pregnant goats. The loading increased plasmatic insulin up to 11/2 hour in kids and transitionally at on hour in pregnant goats only. Intravenously loaded blucose (two injections of 100 mg/kg with ten mints interval) was utilized adequately by adults, however, in females, its clearance was accelerated in lactation and slowed down in pregnancy. Goats at different age and reproductive stages failed to achieve pretest glucose level in two hours. Glucose-stimulated insulin release was greater in kids than adults and in pregnant and lactating than NPNL females. The clearance of released hormone was prompt in kids, pregnant and lactating goats.

Postinsulin (1.0 unit/kg b.w.) hypoglycemia was prompt in kids and lactating goats than in adult males and NPNL and pregnant females. Glycemica level was restored in kids and NPNL females with no appreciable change in two hours during lactation and pregnancy. The administration of glucagon (20 µg/kg) caused greater hyperglycemia in kids and pregnant goats. Released glucose was utilized efficiently by kids and lactating only. Intravenous glibenclamide administration reduced glucose concentration and stimulated insulin release which depended on the pretest glucose level and dose of the drug. Only high dose (5.0 mg/kg b.w) caused significant reduction in glycemia due to greater insulin release.

Calcitocytes were slightly larger in young than in adult animals averaging about 7% of total thyroidal cells without any age associated change. Two pairs of parathyroid gland were present containing densely populated chief cells at the periphery, more pronounceable at old age.

Elevated PTH-m up to 24 hours and calcium at 8th hour after birth were reduced to birth levels around 40th hour. PTH-m again increased up to a week and did not change further whereas calcium showed regular reduction, with peaks on 7th and 21st day, up to three months of age CT markedly increased during 8 and 48 hours except a drop at 32nd hour, after that it reduced up to 21st day noticeably (with peaks on 4,7 and 11th day) and slightly up to three months.

Circulatory calcium an CT decreased after estrus and increased maximally with peaks levels on 8th day for CT and 9th day before the next estrus. PTH-m level gradually increased during pro-, estrus and early metestrus phases but diminished during late metestrus with no change afterwards. Plasmatic CT reduced with no change in calcium and PTH-m for two months of pregnancy. Subsequently CT remained as such except a transitional increase between 100-125 day of gestation and around parturition whereas calcium and PTH-m increased gradually up to about 100th day and subsequently reduced till the end of gestation. Calcium increased positively for the fifteen days and negatively during rest of lactation with slight deviation. CT elevated at kidding was; restored in two days, did not change considerably for a month, remained elevated during 2nd month and reduced during 3rd month of lactation. Reduction in PTH-m onset before parturition continued after kidding for a week, increased up to 15th day, then reduced up to 56 days and again increased up to end of lactation.

Increased plasmatic calcium following infusion of calcium gluconate (50 mg elemental calcium/kg b.w) was cleared efficiently by kids and pregnant goats only. Plasma CT increased tremendously after the load in kids and early lactating goats, however, was metabolized slowly in kids and NPNL females. The loading had reduced PTH-m markedly in kids and early lactating females.

Download Full Thesis
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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 contents
1715.37 KB
2 1 General Account of the study
2937.45 KB
  1.1 Introduction and literature review
  1.2 Materials and methods
  1.3 Results
  1.4 Discussion
3 2 Thyroid gland
15351.94 KB
  2.1 Introduction and literature review
  2.2 Materials and methods
  2.3 Results
  2.4 Discussion
4 3 Glucose and its pancreatic regulatory hormones 110
16218.22 KB
5 4 calcium and its regulatory hormones
28851.96 KB
  4.1 Introduction and Literature review
  4.2 Materials and methods
  4.3 Results
  4.4 Discussion
  4.5 General discussion and overview of the study
  4.6 Conclusion of the study
  4.7 Appendix-A
  4.8 appendix-B
  4.9 References
  4.10 List of author€™s publications