Denys de Catanzaro

Sensitivity to cold pressor pain in dysmenorrheic and non dysmenorrheic women as a function of menstrual cycle phase

&NA; Pain responses (threshold, tolerance, and visual analog ratings) to the cold pressor task were studied in 46 normally menstruating dysmenorrheic and non‐dysmenorrheic women during 2 phases of the menstrual cycle. Twenty‐six women provided measurements during the follicular (days 8–14) and 20 during the luteal (days 15–21) phases of the menstrual cycle. A significantly lower pain threshold was obtained during the luteal as compared to the follicular phase. Pain tolerance showed a similar but non‐significant trend. Visual analog ratings were significantly lower in dysmenorrheic women during the follicular than the luteal phase. Also, these ratings were lower than those of non‐dysmenorrheic women in the follicular phase. This finding may support an adaptation‐levels model, in that dysmenorrheic women report less pain than do non‐dysmenorrheic women because they compare cold pressor pain with internal menstrual pain.

Reproductive status, family interactions, and suicidal ideation: Surveys of the general public and high-risk groups

Abstract Evolutionary modeling predicts an erosion of self-preservative genetic expression in the conjunction of low reproductive potential and burdensomeness toward kin. Although culture and pathology clearly bear on human suicide, some of its emotional concomitants could reflect such evolution. A survey probing reproductive behavior, quality of family contacts, and suicidal ideation was administered to samples of the general public of Ontario and high-suicide-risk groups, including elderly, psychiatric, criminal psychiatric, and homosexual individuals. Within each sample, variance in suicidal ideation related to reproductive and family-social variables. Social isolation and perceived burdensomeness toward family were especially correlated with suicidal ideation.

Effect of predator exposure upon early pregnancy in mice

Female CD-1 and C57 mice were inseminated according to standard procedures and randomly assigned to varied treatments in the first trimester of pregnancy. In the first experiment, mice housed for one week with preselected nonassaultive rats produced very few litters in contrast to controls. In the second experiment, this same effect was observed when inseminated mice were separated from the rat by a wire grid. In the third experiment, inseminated mice were exposed daily to saline or the urine of male or female rats in their home cage bedding. Fewer females exposed to rat urine of either sex produced litters.

Evolutionary limits to self- preservation

Abstract A simple mathematical formula can be derived, on the basis of inclusive fitness theory and notions of reproductive value, to represent the residual capacity of an individual to influence his inclusive fitness. This formula involves the individuals remaining reproductive potential in his expected natural lifetime, plus the summated impacts of his continued existence on the remaining reproductive potentials of each of his kin, each weighted by the coefficient of relationship. In theory, this quantity should predict the extent to which self-preservation is optimally expressed in that individual. For asocial species, the value will vary from zero up to the maximal reproductive value observable, and the logic of the Medawar-Williams theory of senescence should apply directly. However, for highly social species like our own, it can be demonstrated that negative values can also obtain, given the conjunction of low residual reproductive potential and burdensomeness toward kin. Much empirical evidence suggests that outright self-destructiveness is often found in circumstances of such conjunction.

Comparison of the adverse effects of adrenal and ovarian steroids on early pregnancy in mice

In one experiment, female C57- and HS-stain mice were inseminated according to standard procedures and randomly assigned to conditions involving administration of various adrenal and ovarian steroids in the first trimester of pregnancy. The pattern of effects was similar in the two strains, although generally C57 females produced fewer and smaller litters than did HS females. Oestradiol benzoate injections completely blocked pregnancy at doses far less than those effective for other steroids. Corticosterone injections did not produce any significant pregnancy block. Androstenedione injections produced a pregnancy block at 500 micrograms per day. Dehydroepiandrosterone produced a mild pregnancy block at both 500 micrograms and 100 micrograms per day. In a second experiment, the dose-response curve for oestradiol was examined. Daily doses of 0.333 microgram and greater completely blocked pregnancy, a dose of 0.111 microgram did so in the majority of females, and smaller doses had little effect. These results, taken together with other data, suggest that oestrogenic action may mediate the stress-induced block of pregnancy.

Reversal of stress-induced pregnancy blocks in mice by progesterone and metyrapone.

It is established that diverse psychological stressors administered in the first trimester of pregnancy can cause the pregnancy to fail. The physiological mediators of this phenomenon are unknown. In Experiment 1, two strains of female mice were inseminated and randomly assigned to either first trimester physical restraint, restraint plus progesterone, or control conditions. Restrained females produced fewer pregnancies than did controls, and a reversal of this block through the daily administration of 500 micrograms progesterone was seen in HS but not C57 mice. Experiment 2 demonstrated that exposure to a predator will also block pregnancy in the first trimester in C57 mice, and that this can also be counteracted with progesterone administration. Experiment 3 showed that metyrapone, a drug which blocks the conversion of progesterone to corticosterone, also partially reverses a restraint-induced pregnancy block. These results suggest that lowered progesterone levels may be involved in pregnancy blocks induced by psychological stress.

Alteration of Estrogen-Induced Lordosis through Central Administration of Corticosterone in Adrenalectomized-Ovariectomized Rats

Corticosterone was administered through various modes into several brain regions of estrogen-treated adrenalectomized-ovariectomized female rats. Daily administration of 20 µg corticosterone dissolved

Strange-male-induced pregnancy disruption in mice: Reduction of vulnerability by 17β-estradiol antibodies

It is well-established that novel males can disrupt early pregnancy in house mice. Inseminated female C57BL mice were either left undisturbed or each exposed indirectly to a novel HS male through a wire-mesh grid during days 1-6 of pregnancy. Varied dosages of antibodies to 17 beta-estradiol were administered to females exposed to males. Vehicle-treated females exposed to novel males showed fewer litters than did nonexposed controls. Male-exposed females given 1 ml daily of the antibody showed rates of pregnancy comparable to those observed in controls. These data suggest that estrogen levels might play a role in strange-male-induced pregnancy disruptions, converging with evidence implicating estrogens in stress-induced pregnancy blocks.

Pheromones and novel male-induced pregnancy disruptions in mice: exposure to conspecifics is necessary for urine alone to induce an effect.

Previous research indicates a role of pheromones in novel male-induced early pregnancy disruptions. Although some reports suggest that urine alone is sufficient to produce this effect, others raise procedural concerns and fail to replicate such effects. On Days 1 to 5 after insemination, female CF-1 mice had their nasal regions repeatedly painted with water, urine from males housed in isolation, or urine from males housed in proximity to females. Almost all (87.5%) of the control females delivered litters. There was a small nonsignificant reduction in proportion parturient (78.5%) among females exposed to urine of males housed without social contact. The proportion of females parturient (57.1%) after treatment with urine from males housed in proximity to females was significantly different from controls. The magnitude of the effect of socially stimulated male urine is substantially less than that recorded when males are housed directly above inseminated females separated by a wire-mesh grid. These data suggest that production of pregnancy-disrupting male pheromones is stimulated by contact with conspecifics.

Facilitation of estrogen-induced receptivity through metyrapone administration in ovariectomized rats

Previously it has been established that adrenalectomy facilitates lordosis in estrogen-primed ovariectomized female rats and that corticosterone administration restores lordosis to preadrenalectomy levels. The present study examined the effects of an inhibitor of the synthesis of corticosterone, metyrapone, upon lordosis in ovariectomized females. In Experiment 1, chronic administration of moderate doses of metyrapone was found to facilitate lordosis. In Experiment 2, a single metyrapone administration at various doses and time intervals before testing had a mild facilitatory effect on lordosis. Experiment 3 compared the effects of metyrapone on ovariectomized and adrenalectomized-ovariectomized females. The absence of a facilitatory effect in adrenalectomized females suggests that the drugs effect on lordosis is mediated by its established inhibitory effects on 11 beta-hydroxylation in the adrenal. These data are consistent with indications that corticosterone titer modulates female receptivity.