Pinealectomy and Sexual Rhythm in Female Rats

Takeo, Yuji; Anazawa, Michio; Shirama, Kazuhiko; Shimizu, Kiyoshí; Maekawa, Kyutaro

doi:10.1507/endocrj1954.22.219

Cited by 4 publications

(5 citation statements)

References 12 publications

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“…Previous results on the effect of pinealectomy on the oestrous cycle in rats are conflicting. In the experiment reported here, there was no change in the duration of the oestral phase of the cycle, while others indicate an increase in the oes trous phase [Chit et al, 1964], Takeo et al [1975], fail to report any effect of pinealec tomy on the oestrous cycle at all. Differences in photoperiods, in rat strains employed as well as in timing of pineal ablation, may account for the variations in the results ob tained.…”

Section: Discussioncontrasting

confidence: 58%

Effect of Pinealectomy on Heat-Induced Endocrine Changes in Female Rats

Magal¹,

Kaplanski

Sod‐Moriah³

et al. 1983

Horm Res

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Exposure of pinealectomized rats to high ambient temperature (35 °C; PXH) brought about a diminution in pituitary weight and LH content when compared to their sham-operated peers (35 °C) or to pinealectomized controls (22 °C). Serum corticosterone level of PXH rats was significantly depressed while heat or pinealectomy alone had no effect. Mean oestrous cycle length was prolonged and blood serum progesterone was increased in the heat-exposed rats. However, the extended oestrous cycles and elevated serum progesterone levels of heat-exposed rats were depressed or abolished by pineal ablation. Thus, the pineal appears to exert a moderating effect on heat-induced endocrine changes in female rats. No changes were noticed in uterine and ovarian weights corrected for body weights either on the day of vaginal opening, at occurrence of the oestrous phase expressed as percentage of total oestrous cycle, or in N-acetyltransferase and hydroxyindole-O-methyltransferase activities.

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Section: Discussioncontrasting

confidence: 58%

Effect of Pinealectomy on Heat-Induced Endocrine Changes in Female Rats

Magal¹,

Kaplanski

Sod‐Moriah³

et al. 1983

Horm Res

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“…This coincides with the previous results obtained by Takahashi and Suzuki (1969) and by members of our laboratory (Takeo et al, 1974). LL-0 rats resumed cyclicity in higher incidence than LL-70 ones by the injection of reserpine for 2 days and the restored cyclicity eventually disappeared by subsequent continuous illumination.…”

Section: Discussionsupporting

confidence: 92%

“…However, Takahashi and Suzuki (1969) and Takeo et al(1974) reported that the rats exposed to LL from the day of birth were not so susceptible to constant illumination in manifestation of persistent estrus as the rats subjected to LL from advanced ages. In the present experiment, ovarian morphology was compared between the rats exposed to LL from 70 days of age and from the day of birth.…”

Section: Synopsismentioning

confidence: 99%

Recurrence of Estrous Cycles in the Light-Induced Persistent Estrous Rats by Reserpine

et al. 1976

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SynopsisEffect of continuous illumination (LL) on ovarian functions was compared at various ages between the rats exposed to LL from 70 days of age (LL-70) and exposed to LL from the day of birth (LL-0).LL-0 rats retained corpora lutea in their ovaries in higher incidence than LL-70 rats. Effect of reserpine on the restoration of cyclicity was studied in LL-0 and LL-70 rats shortly after they became persistent-estrous.LL-0 rats restored cyclicity in higher incidence than in LL-70 rats.Exposure of adult female rats to continuous illumination brings about persistent estrus which is characterized by prolonged vaginal cornification, failure of spontaneous ovulation and cystic follicular ovaries devoid of corpora lutea (see the review by Reiter and Fraschini, 1969). Ovarian weight and gonadotrophin secretion in these rats were gradually reduced as the exposure time to constant light elapsed (Honma et. al., 1972;Lawton and Schwartz, 1967).However, Takahashi and Suzuki (1969) and Takeo et al.(1974) reported that the rats exposed to LL from the day of birth were not so susceptible to constant illumination in manifestation of persistent estrus as the rats subjected to LL from advanced ages. In the present experiment, ovarian morphology was compared between the rats exposed to LL from 70 days of age and from the day of birth. The responsiveness to reserpine which is believed to modify gonadotrophin secretion (Ganong, 1972) and levels of biogenic amines in central nervous system (Bertler et al., 1956 ;Shore et al., 1955) was also investigated in persistent estrus rats of LL-70 and LL-0. Materials and MethodsWistar female rats were used. To obtain LL-0 rats, pregnant rats were kept in a continuous lighting condition, and the pups were raised in the similar conditions. Adult female rats exhibiting 4-day estrous cycle were transferred to constant light regimen when the animals reached 70 days of age (LL-70). The light source was white fluorescent lamps (about 500-600 lux). Daily vaginal smears since the opening of the vaginal orifice were examined at 10-11 a.m. until the day of sacrifice.Totally 23 of LL-70, 24 of LL-0 and 20 of control (12 hours light-12 hours darkness) rats were sacriries and uteri were weighed. The ovaries were fixed in Bouin's sol., cut in paraffin and stained with hematoxylin and eosin and were examined histologically.Eleven LL-70 and fourteen LL-0 rats which came to show continuous estrus for ten days were injected with reserpine subcutaneously once a day for 2 days. Daily dose of reserpine was 1mg/kg body weight. Eleven rats in both groups were sacrificed 2 to 3 weeks after the first injection of reserpine. Three of LL-0 rats similarly treated were kept for 32-47

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“…1, the method of Maekawa (1956) was used for the expression of vaginal smear records; the thin baseline of the figures corresponds to non-estrous stages which contain proestrus, metestrus and diestrus, and the thick top to perfect estrus. As authors' previous paper (Takeo et al, 1974) Fig. 1.…”

Section: Methodsmentioning

confidence: 57%

“…However, the rats brought up from birth under continuous illumination maintain the estrous cycles for long time in their postpuberal life (Maekawa, 1959;Takahashi and Suzuki, 1969;Hoffmann, 1973;Takeo et al, 1974). On the contrary, immature rats at about 30days of age exhibit the persistent estrus soon after exposure to continuous illumination (Takahashi and Suzuki, 1969;Takeo et al, 1974).…”

mentioning

confidence: 99%