The purpose of this study was to determine whether core temperature (T(c)) telemetry could be used in ambulatory women to track changes in the circadian T(c) rhythm during different phases of the menstrual cycle and, more specifically, to detect impending ovulation. T(c) was measured in four women who ingested a series of disposable temperature sensors. Data were collected each minute for 2-7 days and analyzed in 36-h segments by automated cosinor analysis to determine the mesor (mean temperature), amplitude, period, acrophase (time of peak temperature), and predicted circadian minimum core temperature (T(c-min)) for each cycle. The T(c) mesor was higher (P < or = 0.001) in the luteal (L) phase (37.39 +/-0.13 degrees C) and lower in the preovulatory (P) phase (36.91 +/-0.11 degrees C) compared with the follicular (F) phase (37.08 +/-0.13 degrees C). The predicted T(c-min) was also greater in L (37.06 +/- 0.14 degrees C) than in menses (M; 36.69 +/- 0.13 degrees C), F (36. 6 +/- 0.16 degrees C), and P (36.38 +/- 0.08 degrees C) (P < or = 0. 0001). During P, the predicted T(c-min) was significantly decreased compared with M and F (P < or = 0.0001). The amplitude of the T(c) rhythm was significantly reduced in L compared with all other phases (P < or = 0.005). Neither the period nor acrophase was affected by menstrual cycle phase in ambulatory subjects. The use of an ingestible temperature sensor in conjunction with fast and accurate cosinor analysis provides a noninvasive method to mark menstrual phases, including the critical preovulatory period.

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The effects of prepuberal gonadectomy on adrenal function were studied in both male and female rats. Steroid production was measured in vitro using either adrenal homogenates or slices. Adrenal tissue from castrated animals of either sex produced less steroid when determined by acid fluorescence or ultraviolet absorption. The effect was reversed after replacement with testosterone or estradiol. No difference due to castration was observed when steroid production was measured with blue tetrazolium. Corticosterone added in vitro to adrenal tissue from gonadectomized rats was converted to a fluorescence negative, ultraviolet negative, blue tetrazolium positive metabolite. This conversion was inhibited by gonadal hormone replacement in. vivo. The metabolite was identified by Rf both before and after acetylation on several paper and thin layer chromatographic systems and also by infrared spectroscopy as 3/3,5o:-tetrahydrocorticosterone (compound R). Two additional compounds tentatively identified by chromatography alone were 3a,5a-tetrahydrocorticosterone and 5a-dihydrocorticosterone. Further studies showed that the decreased production of steroids by adrenal homogenates observed after ovariectomy was abolished by preincubation of the tissue as slices. Such preincubation concomitantly reduced the conversion of added corticosterone to compound R. The reaction involves 2 enzymes, 5a-reductase and 3-hydroxysteroid dehydrogenase. Activity of the latter is not increased after castration. The results demonstrate that gonadectomy enhances the capacity of the adrenal gland to convert corticosterone to compound R and other tetrahydro metabolites. The data are consistent with the hypothesis that adrenal 5a-reductase activity is increased after castration and is inhibited by replacement with testosterone or estradiol. These effects may represent a physiologic mechanism for regulation of adrenal steroid secretion. {Endo-crinology 87: 1257{Endo-crinology 87: , 1970 /CONSIDERABLE evidence is available \jk to indicate that pituitary-adrenal function is influenced by the gonadal hormones (2). However, physiologic roles for estradiol and testosterone in the regulation of adrenal function have been difficult to define. The available data seem contradictory since both stimulatory and inhibitory effects have been described for both hormones. Much of the disagreement can be related to wide variations in experimental designs used in different laboratories. For example, dose is a critical factor. The effects of estradiol and testosterone appear to

The effects of prepuberal gonadectomy on pituitary secretion of ACTH were studied in adult male rats. Plasma concentration of ACTH in unstressed adrenalectomized rats was increased following orchiectomy to 197% (95% confidence limits 134-289%) of the control level. Higher plasma ACTH concentrations were also observed in castrated animals with adrenals intact after the acute stress of ether anesthesia when compared to similarly stressed controls (159%; 121-215%). In both experiments, replacement with testosterone reversed the response to orchiectomy. Unstimulated release of ACTH in vitro by whole pituitary glands from orchiectomized donors, without or with testosterone replacement in vivo, did not differ from that of control glands. Addition of stalk-median eminence extract to the incubating glands, however, resulted in a greater R EMOVAL of the ovaries from rats results in decreased synthesis and release of ACTH (1). In addition, adrenal secretion of corticosterone is also significantly depressed, independent of changes in ACTH secretion (2). These effects are reversed with estradiol administration. The data thus demonstrate stimulation of the pituitary-adrenal system by estrogen at two different sites, i.e., significant and separable enhancement of secretion of both pituitary ACTH and adrenal corticosterone.