Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Farmácia, Florianópolis, 2014. / Made available in DSpace on 2014-08-06T18:02:40Z (GMT). No. of bitstreams: 1 326778.pdf: 1607245 bytes, checksum: 36642cd4411a839a236f802925f916af (MD5) Previous issue date: 2014 / Abstract : Congenital hypothyroidism can lead to a variety of neurochemical and morphophysiological alterations that may be associated with learning deficits, hypomyelination and delayed development of the central nervous system (CNS). In this study, it has been investigated whether the hormone 3,3',5' -triiodothyronine (reverse T3, rT3) is able to reverse the biochemical changes caused by congenital hypothyroidism in hippocampal slices from 15 day-old rats, as well as the mechanism of action of this hormone. Congenital hypothyroidism was induced by adding 0.05% propylthiouracil (PTU) in the drinking water from gestation day 8 and continually up to lactation day 15. Euthyroid rats, receiving only water during the same period, were used as controls. Control and hypothyroid pups were used at 15 day-old, considering the period of maximum synaptogenesis. Hippocampal slices from controls and hypothyroid pups were incubated for 30 min with or without rT3 (10-9 M). Receptor antagonists (RGD and AP-5), inhibitors or activators of cell signaling pathways of p38, CaMKII, ERK1/2, PKA and PKC (SB239063, KN-93, PD98059, H89 and PMA, respectively), as well as L-type voltage-dependent calcium channel blocker (nifedipine) and intracellular calcium chelator (BAPTA -AM), were used to determine the mechanisms involved in the nongenomic action of rT3 on hippocampal cells. We also analyzed some biochemical markers (aminotransferase activity) and oxidative stress parameters, as well as changes in the uptake of 45Ca++ and [14C]-2-deoxy-D-glucose in the hippocampus of immature rats treated or not with rT3. Results showed that hypothyroidism leads to accumulation of intracellular Ca++ and induces oxidative stress. On the other hand, rT3, previously considered as an inactive metabolite of thyroid hormones (TH), was able to reverse, at least some of the biochemical changes induced by congenital hypothyroidism. In this context, rT3 interacts with the surface ?vß3 integrin receptors activating several signal transduction pathways (PKA, CaMKII, ERK1/2 and p38). These events cause a decrease in 45Ca++ influx, stimulation in [14C]-2-deoxy-D-glucose uptake, as well as reverse the oxidative stress induced by congenital hypothyroidism. Considering that changes in TH levels could be associated with neurodegenerative disorders, depression, anxiety, among others, the understanding of mechanisms of action of these hormones might allow the development of more specific and targeted drugs in controlling several physiopathological disorders of CNS.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. / Made available in DSpace on 2012-10-18T07:37:32Z (GMT). No. of bitstreams: 0Bitstream added on 2014-09-26T00:44:28Z : No. of bitstreams: 1 176951.pdf: 4494969 bytes, checksum: d0ed3bf702060b146f11816f69d162aa (MD5) / Avalia o programa de rastreamento da Secretaria de Estado da Saúde de Santa Catarina, em relação ao hipotireoidismo congênito primário e estima sua prevalência nas crianças rastreadas. Sugere estratégias necessárias para agilizar as várias etapas do programa principalmente a idade da primeira coleta da amostra de sangue para dosagem de tireotrofina e o tempo transcorrido entre a coleta e a chegada da amostra ao Laboratório Central de Saúde Pública.

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.