Hormonal and monoaminergic influences on masculine copulatory behavior in the female rat.

Ovariectomized female rats receiving estradiol benzoate (EB), testosterone propionate, or no hormone treatment were administered parachlorophenylalanine (PCPA), alone, or in combination with pargyline. Sixteen days of EB-treatment resulted in hypertrophied pituitaries and concomitant pressure damage to ventral portions of the brain. Irrespective of hormonal condition females receiving PCPA treatment displayed more masculine copulatory behavior than females receiving PCPA + pargyline or saline treatment. In a second study PCPA also potentiated masculine copulatory behavior in ovariectomized and adrenalectomized females receiving no hormone treatment. The ejaculatory pattern was observed in one of eight females receiving EB + PCPA treatment and in two of seven ovariectomized-adrenalectomized females receiving PCPA treatment. The possible role of the hypothalamic-pituitary-adrenal system in the expression of the ejaculatory pattern in male and female rats is discussed.     

Hormonal influences on the muscle-bone feedback system: a perspective

Hormones, muscle and bone tissues have co-existed virtually during the whole evolution of vertebrates, and it is obvious that they constitute a complex system able to cope with needs and challenges arising from a variety of physiological and locomotive needs. All body movements are produced by co-ordinated contractions of skeletal muscles, while consequent dynamic muscle work provides the fundamental source of mechanical loading to the skeleton. Mechanical competence of the skeleton is principally maintained by a mechanosensory feedback system that senses the loading-induced deformations within the bones and maintains the skeletal rigidity through structural adaptation. In contrast to the prevalent view suggesting a modulatory effect of hormones on the sensitivity of the mechanosensory system, a new conceptual scheme is proposed. In particular, it is argued that the mechanical and hormonal functions in the skeleton are fundamentally independent but can be seemingly interactive through hormonally-induced modifications in the bone structure, those basically forming a mineral reservoir for maintenance of physiological homeostasis. Whenever needed, utilization of this strategically placed reservoir would not essentially compromise the mechanical competence and locomotive capability of the skeleton. Although plausible, the present view is necessarily speculative and awaits corroborative experimental evidence.     

Hormonal disturbances and effect of pharmaca.

The hormonal milieu of the organism may exert certain influences on the activity and lasting of the effect of some drugs. This was demonstrated in female rats with the example of a steroid hormone (estrone) and a short acting barbiturate derivative (hexobarbital). Estrus produced with estrone is not to be influenced by ovariectomy. Hyperthyrosis lead to the cumulation of estrogens in active form and lengthened their effect. Hypothyrosis accelerated estrogen metabolism inducing a relatively ephemer effect of estrone. Hexobarbital metabolism is faster in ovariectomised rats as well as in thyroidectomised ones than in controls. The catatoxic effect of testosterone is bringing about a short anesthesia. Hyperthyrosis reduced the effect of hexobarbital to one fourth of the control values. A special care is necessary in administering drugs when endocrine disorders are present. Individual dosages of the pharmaca may be taken into consideration to adapt the right dosages to the hormonal disturbances.     

Hormonal influences on women's extra-pair sexual interests: The moderating impact of partner attractiveness

Based on the idea that women are especially attracted to ancestral markers of male genetic quality when conceptive in their cycle, scholars have conjectured that increases in women's extra-pair sexual interests during the conceptive phase of the cycle are moderated by their primary partners' sexual attractiveness. Multiple studies have examined this prediction, with largely supportive but mixed results. The current study is the first to examine whether hormonal influences—thought to mediate cycle shifts—on women's extra-pair sexual interests are moderated by partner attractiveness. 213 naturally cycling, romantically involved women (181 attending multiple sessions) participated in up to four sessions over about a month. Estrogen and progesterone levels were measured multiple times across women's cycles. Male partner attractiveness moderated associations between progesterone levels (though not estrogen levels) and women's extra-pair sexual interests. A negative association between progesterone levels and extra-pair sexual interests, a composite measure, was observed for women with relatively unattractive partners. For women with relatively attractive partners, no clear association emerged. The interaction between progesterone and partner attractiveness was robust for women's interest in extra-pair sex, a component preregistered as exploratory. The interaction effect was also significant for the absolute intensity of women's extra-pair attraction (a component item referenced in the preregistration) but was non-significant for the frequency of women's extra-pair attraction relative to typical days (a composite component specified in the preregistration). These findings inform theoretical understandings of women's sexuality.     

The effect of selenium-deficiency on rat fat-cell glucose oxidation.

When rats are fed a selenium-deficient diet, the glutathione peroxidase activity of epididymal fat-cells decreases to 5-9% of that of control rats fed the same diet supplemented with 0.5 p.p.m. of selenium as sodium selenite. [1-14C]Glucose oxidation in fat-cells from rats fed a selenium-deficient diet is unresponsive to the action of t-butyl hydroperoxide, which stimulates 14CO2 formation from [1-14C]glucose 4-fold in control rats. Insulin enhances [1-14C]glucose oxidation and incorporation into lipids in fat-cells from both groups of rats; however, the response elicited is reduced in fat-cells prepared from selenium-deficient animals. The 'C-1/C-6 ratio' (ratio of glucose C-1 to glucose C-6 oxidized) is enhanced by insulin to a similar degree in fat-cells from both groups of animals. The stimulatory action of Zn2+ and dithiothreitol on [1-14C]glucose oxidation observed in fat-cells from selenium-supplemented rats is greatly reduced in fat-cells from selenium-deficient rats. [1-14C]Glucose oxidation in fat-cells from both groups of animals is highly sensitive to the stimulatory action of adenosine. It is concluded that the enhanced formation and glutathione-linked destruction of H2O2 plays, at the most, only a minor role in the stimulation of the flux of glucose through the pentose phosphate pathway elicited by insulin, although elimination of glutathione peroxidase activity may influence the action of insulin on glucose oxidation. Production and subsequent destruction of H2O2 may play an important role in the stimulatory action of Zn2+ and dithiothreitol on fat-cell [1-14C]glucose oxidation.     

The influences of leukotriene C4 on the metabolism of labelled glucose in uteri isolated from ovariectomized and from ovariectomized-estrogenized rats. Effects of indomethacin

The effects of leukotriene C4 (LTC4), nordihydroguaiaretic acid (NDGA) and FPL-55712, on the metabolism of labelled glucose (U14C-glucose) in uteri isolated from spayed rats and from spayed-estrogenized rats, incubated in the presence and in the absence of indomethacin, were explored. Indomethacin (10(-6)M), enhanced significantly 14CO2 formation from labelled glucose, both in uteri from ovariectomized rats and in uteri from ovariectomized-estrogenized animals. In uteri from spayed not-estrogenized rats, expose 'in vitro' to indomethacin, NDGA (10(-5)M), an inhibitor of the 5-lipoxygenase, as well as FPL-55712 (10(-5)M), a LT antagonist, reduced significantly the enhanced metabolism of glucose evoked by indomethacin, an inhibitor of the cyclo- oxygenase. On the other hand, LTC4 (10(-7)M), augmented the metabolism of labelled glucose, reaching values even greater than those induced by indomethacin. In the spayed-estrogenized group LTC4 (10(-10)-10(-7)M) enhanced the formation of labelled CO2 from labelled glucose as much as indomethacin (10(-6)M) did, whereas neither NDGA nor FPL-55712 were effective. In addition, in uteri from ovariectomized-estrogenized rats, incubated with indomethacin, NDGA and FPL-55712, decreased the augmenting action of indomethacin on glucose metabolism, whereas LTC4 (10(-10)-10(-7)M) evoked a complete reversal of the inhibitory influence of NDGA on the formation of 14CO2. The force-going results suggest that tissue 5-lipoxygenase products, particularly LTC4, are involved in the metabolism of labelled glucose by rat uteri, mainly when the cyclo-oxygenase pathway is inhibited by indomethacin and the tissue is deprived of estradiol.(ABSTRACT TRUNCATED AT 250 WORDS)