Hisashi Ooka

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Wistar rats were made hypothyroidic by intraperitoneal thyroxine (T4) injection during the first 10 days of neonatal life. Levels of T4, 3,3',5-triiodothyronine (T3), thyroid-stimulating hormone (TSH) and prolactin in the blood of these rats were measured by radioimmunoassay. The T4 levels are about two-thirds of control values up to 20 months of age. T3(More)
Long-Evans female rats, 21 days of age, were weaned and placed on a control (Purina Rat Chow) diet, on a tryptophan deficient diet (T-) and on a diet complete in quality (Purina Rat Chow) but restricted to the daily amount consumed by the rats on the T- diet (pair-feeding). All animals were maintained on these diets for 1 and 2 months and then one group of(More)
Diets containing tryptophan in concentrations 30 and 40 percent of those fed to controls from weaning to 24-30 months or more, can delay aging in Long-Evans female rats. Mortality among low-tryptophan-fed rats was greater in the juvenile period, but substantially less than controls at late ages. Histological biomarkers of aging were also delayed after(More)
The life durations of hypo- and hyperthyroid Wistar rats were measured under clean conventional conditions. The amount of exogenous T4 (thyroxine), which is sufficient to elevate T4 levels in the blood, decreased with age. The rats which were made hypothyroid by the neonatal T4 treatment had a longer lifespan than control. The lifespans of hyperthyroid(More)
Age-related changes in the numbers of mammotrophs, somatotrophs, mammosomatotrophs, and the cells of other types in the anterior pituitary of female Wistar rat were measured by flow cytometry. The mammotrophs increased with age, and the somatotrophs decreased with senescence. The mammosomatotrophs increased remarkably in senescent rats, and these cells of(More)
We measured the influence of prolactin-releasing neuropeptides on mammotroph proliferation in cultures of rat adenohypophysis cells using flow cytometry. Angiotensin II (AII) increased mammotroph proliferation. Other peptides with hormone-releasing activities did not promote growth. Tamoxifen inhibited mammotroph proliferation in control and AII-containing(More)
Presbycusis is the impairment of auditory function associated with aging, which stems from peripheral cochlear lesions and degeneration of the central auditory process. The effect of age-induced peripheral hearing loss on the central auditory process is not fully understood. C57Bl/6 (C57) mice present accelerated peripheral hearing loss, which is well(More)
Prolactin (PRL) exerts a direct effect on the central nervous system, reaching the PRL-responsive brain regions via cerebro-spinal fluid (CSF). The hormone enters the CSF by a specific receptor-mediated transport mechanism that is localized on the epithelium of the choroid plexus (CP) of brain ventricles. PRL interactions with the CP in aging were examined(More)
In order to examine the hypothalamic control of acidophilic proliferation, anterior pituitary cells from adult female rats were cultured with or without rat growth hormone-releasing factor fragment 1-29 (GRF-29). Changes in the numbers of mammotrophs and somatotrophs during culture were measured by immunocytochemical staining. The addition of GRF suppressed(More)