Thyroid disorders cause abnormal puberty, indicating interactions between the hypothalamus-pituitary-thyroid (HPT) and hypothalamus-pituitary-gonadal (HPG) axes, which are important in pubertal development. The hypothalamic gonadotropin-inhibitory hormone (GnIH) was shown to be decreased in the early prepubertal stage, suggesting the role of GnIH on pubertal onset. Here, we investigated whether thyroid dysfunction affects pubertal onset in female mice via GnIH regulation. Hypothyroidism showed delayed pubertal onset with increased GnIH expression and reduced pituitary-gonadal activity. Remarkably, knockout of GnIH prevented the effect of hypothyroidism to delay the pubertal onset, resulting in indistinguishable pubertal timing in GnIH-knockout female mice between control and hypothyroidism-induced group, indicating that increased GnIH expression induced by hypothyroidism may lead to delayed puberty. In contrast, hyperthyroidism led to a decrease in GnIH expression, however pubertal onset was normal, implying further reduction of the inhibitory GnIH had little effect on the phenotypical change. Critically, thyroid hormone suppressed GnIH expression in hypothalamic explants and GnIH neurons expressed thyroid hormone receptors to convey the thyroid status. Moreover, the thyroid status highly regulated the chromatin modifications of GnIH promoter, H3acetylation and H3K9tri-methylation. These findings indicate a novel function of GnIH to mediate HPT-HPG interactions that contribute to proper pubertal development.
It is known that hypothyroidism delays puberty in mammals. Interaction between the hypothalamo-pituitary-thyroid (HPT) and hypothalamo-pituitary-gonadal (HPG) axes may be important processes in delayed puberty. Gonadotropin-inhibitory hormone (GnIH) is a newly discovered hypothalamic neuropeptide that inhibits gonadotropin synthesis and release in quail. It now appears that GnIH is conserved across various mammals and primates, including humans, and inhibits reproduction. We have further demonstrated that GnIH is involved in pubertal delay induced by thyroid dysfunction in female mice. Hypothyroidism delays pubertal onset with the increase in hypothalamic GnIH expression and the decrease in circulating gonadotropin and estradiol levels. Thyroid status regulates GnIH expression by epigenetic modification of the GnIH promoter region. Furthermore, knockout of GnIH gene abolishes the effect of hypothyroidism on delayed pubertal onset. Accordingly, it is considered that GnIH is a mediator of pubertal disorder induced by thyroid dysfunction. This is a novel function of GnIH that interacts between the HPT-HPG axes in pubertal onset delay. This mini-review summarizes the structure, expression, and function of GnIH and highlights the action of GnIH in pubertal disorder induced by thyroid dysfunction.
IntroductionSome patients with acute phase schizophrenia are too agitated to receive treatment in a normal hospital room. They must be isolated for the treatment. Although the stay in an isolation room seems harmful to patients, no study detailing the stress response to isolation with objective measures has been conducted.MethodNine patients with schizophrenia or schizoaffective disorder were recruited (mean age = 52 years, male = 3, schizophrenic = 7). At the time of evaluation, they were staying in an isolation room. To evaluate stress response to the environment, the level of salivary amylase was tested when the patients were either in the isolation room (T1) or out of the isolation room (T2). T2 was defined as one hour after the room's door was opened. The data were analyzed by the Wilcoxon rank-sum test.ResultThere is a significant difference between the median (range) levels of salivary amylase at T1 and T2 (19 [2–146] vs 44 [9–178], respectively, P = 0.021).DiscussionThe data demonstrate that the stress response at T2 was stronger than that at T1, which suggests that the isolation room environment is less stressful to the patient compared to being outside the room. An environment that has many potential stimuli, such as the presence of other patients and a television in the lobby, may be harmful to patients with acute phase schizophrenia. Therefore, although the isolation room is apparently harmful, it could, in fact, have a positive effect on patients.Disclosure of interestThe authors have not supplied their declaration of competing interest.
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