Thesis (M.A.(Population and Reproductive Health Research))--Mahidol University, 2005. / LICL has E-Thesis 0004 ; please contact computer services.

Thesis (M.A.)--University of Central Florida, 2009. / Adviser: Ty Matejowsky. Includes bibliographical references (p. 34-39).

Falk's pivotal 1961 study showed that rats would drink excessive amounts of water when exposed to a time based schedule of reinforcement. Since then, schedule-induced drinking or polydipsia, has been demonstrated with several species and with a variety of different behaviors. Rats, the most commonly used animal, have been shown to drink excessive amounts of water under a variety of different time based schedules of reinforcement; exclusively during a free operant procedure. The current study shows that water drinking can be induced during a discrete trial procedure, and instead of using a time-based schedule of reinforcement, this study used a variable-ratio schedule of reinforcement. The results showed that excessive water drinking was induced under these conditions with a canine.

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Recent experimental approaches attribute value to events occurring during intrauterine life as crucial in the onset of several diseases during postnatal life. Thyroid hormones (TH) are critical to the physiology of metabolism and body development. The aim of this study was to investigate the repercussions of lack of TH during pregnancy on body mass gain, metabolic profile, ingestive behavior of food, sodium (0.3M NaCl) and water in rat offspring at different postnatal ages. The experimental gestational hypothyroidism (EGH) was induced by the administration of 0.02% methimazole (MMI) in ad libitum drinking water from day 9 of gestation until delivery. Offspring (males and females) from MMI-treated dams (OMTD) were compared to their corresponding control offspring (i.e. male and female offspring from water-treated dams; OWTD). Insulin tolerance test (ITT) and glucose tolerance test (GTT) were also performed. Two- or three-way ANOVA followed by Bonferroni post-test were performed when necessary. OMTD showed lower body weight on PND 23 and 30 (p<0.0001). Similar profile was observed when the offspring were separated by gender, at least during the experimental period (PND 60, 90 and 120; p<0.0001 for both genders). However, there was no difference in the amount of food intake when males of OMTD (m-OMTD) were compared to OWTD (m-OWTD). Female of OMTD (f-OMTD) had lower ability to reduce glucose plasma level at ITT (p = 0.0224), otherwise, no change in GTT (p = 0.1313) was observed. At PND 60, glucose plasma level was higher in f-OMTD than in f-OWTD (p = 0.013). In m-OMTD, plasma cholesterol was higher in PND 60 and lower on PND 120 (p <0.0001), when compared to m-OWTD. In f-OMTD, cholesterol was lower only at PND 120 (p = 0.035). The high density lipoprotein (HDL) cholesterol was lower in OMTD on PND 15 and 30 (p = 0.04) and remained lower only in f-OMTD on PND 120 (p = 0.024). Moreover, EGH induced an increased in plasma triglycerides (TGL), as well as, in serum level of very low density lipoprotein (VLDL) cholesterol in offspring at DPN 15 (p = 0.039) and also after puberty (at DPN 60), but only the m-OMTD (p < 0.0001). The serum urea was lower in OMTD on PND 15 and 30. Interestingly, serum urea was inverted at DPN 60 in both, m- and f-OMTD (p = 0.006, and p = 0.003, respectively), when compared to their respective control groups. At PND 120, retroperitoneal fat weight was lower both in m- (p = 0.05) and f-OMTD (p = 0.009). Additionally, at all studied ages, relative kidney and liver mass was lower in m- (p = 0.001) and f-OMTD (p = 0.008). In conclusion, we demonstrated, for the first time, that maternal TH are critical to the ontogenetic development of systems that regulate energy metabolism throughout the life of the offspring, resulting in a reduction in body mass, biochemical instability throughout the life, lower sensitivity to insulin in females, and, a delay in the development of critical organs for the metabolism of macronutrients. / Recentes abordagens experimentais têm imputado valor aos eventos ocorridos durante a vida intrauterina como cruciais no aparecimento de doenças na vida pós-natal. Os hormônios tireoidianos (HTs) são críticos para fisiologia do metabolismo e desenvolvimento corporal. O objetivo do presente estudo foi investigar as repercussões da carência dos HTs em ratas prenhes na evolução ponderal da massa corporal, perfil bioquímico, comportamento ingestivo de ração, água e sódio (NaCl 0,3M) da prole em diferentes idades pós-natais. O hipotireoidismo gestacional experimental (HGE) foi induzido através da adicão de metimazol 0,02% na água de beber a partir do dia 9 de gestação até o parto. O grupo de prole (machos e fêmeas) de mães hipotireoideanas (PMH) foi comparado ao grupo controle de mães eutireoideanas (PME). Realizou-se o teste de tolerância à insulina (TTI) e o teste de tolerância à glicose (TTG). Os dados foram submetidos ao teste de ANOVA de duas ou três vias, quando necessário, seguidos do pós-teste de Bonferroni. De acordo com os resultados obtidos, observou-se que a PMH apresentou massa corporal menor aos 23 e 30 dias pós-natal (DPN) (p<0,0001). Padrão similar foi encontrado quando as proles foram separadas por gênero, aos 60, 90 e 120 DPN (p<0,0001, para ambos os gêneros). No entanto, não houve diferença significativa na ingestão de ração entre os machos PMH e PME. As fêmeas da prole de mães hipotireoideanas (f-PMH) apresentaram menor capacidade de reduzir a glicemia no TTI (p=0,0224) sem alteração no TTG. Aos 60 DPN, a concentração sérica de glicose foi maior nas f-PMH (p = 0,013) que nas f-PME. Nos machos prole de mães hipotireoideanas (m-PMH) o colesterol plasmático foi elevado aos 60 DPN e reduziu aos 120 DPN (p<0,0001), quando comparado aos machos prole de mães eutireoideanas (m-PME). Nas f-PMH o colesterol sérico foi menor somente aos 120 DPN (p=0,035). O HDL sérico foi menor na PMH aos 15 e 30 DPN (p=0,04), e continuou menor nas f-PMH aos 60, 90 e 120 DPN (p=0,024). Entretanto, o HGE elevou as concentrações séricas de TGL, bem como de VLDL, na PMH aos 15 DPN, e após a puberdade (aos 60 DPN), somente nos m-PMH (p<0,0001). A concentração sérica de ureia foi menor na PMH aos 15 e 30 DPN. Interessantemente, a ureia sérica foi invertida aos 60 DPN, se apresentando elevada tanto em m- (p=0,006) como em f-PMH (p=0,003), quando comparados aos respectivos grupos controle. Aos 120 DPN, a massa da gordura retroperitoneal foi menor tanto em m- (p=0,05) como em f-PMH (p=0,009). Adicionalmente, em todas idades estudadas, as massas relativas dos rins e do fígado foram menores tanto em m- (p=0,001) como em f- da PMH (p=0,008). Em conclusão, demonstrou-se, pela primeira vez, que os HTs maternos são críticos para o desenvolvimento ontogênico de sistemas que regulam o metabolismo de energia ao longo da vida da prole, resultando numa redução da massa corporal, instabilidade bioquímica ao longo da vida, menor sensibilidade à insulina em fêmeas, e um atraso no desenvolvimento de órgãos críticos para o metabolismo de macronutrientes.