Lainattua eräältä tieteelliseltä keskustelulistalta:
--- eräs ehkä tehokkaimmista tavoista vähentää
testosteronitasoja lienee miesten toiminta pikkulasten ja vauvojen hoivan parissa. Siitä on useita viitteitä, tässä yksi:
Berg, S. J., & Wynne-Edwards, K. E. (2001). Changes in Testosterone,
Cortisol, and Estradiol Levels in Men Becoming Fathers [Original Article].
Mayo Clin Proc., 76, 582?592.
? Objective: To quantify longitudinally steroid hormone (testosterone,
cortisol, and estradiol) concentrations in men becoming fathers for the
first time ("dads").
? Subjects and Methods: Volunteer study subjects were recruited from
first-trimester prenatal classes in Kingston, Ontario, in February 1999.
Twenty-three dads provided saliva samples from recruitment through 3 months after the birth of their children. Fourteen men who were not fathers were recruited from the general population to serve as age-matched controls for season and time of day. Estradiol, testosterone, and cortisol levels were quantified.
? Results: After controlling for effects of time of day and season, dads had
lower mean ± SE testosterone (6.5±0.7 vs 10.0±0.9 ng/dL; P<.005) and
cortisol (morning values, 0.30±0.05 vs 0.53±0.05 µg/dL; P<.005)
concentrations, a higher proportion of samples with detectable estradiol
concentrations (68% [308/454] vs 57% [87/154]; P=.01), and higher estradiol
concentrations in those detectable samples (3.81±0.09 pg/mL [13 dads] vs
3.26±0.11 pg/mL [9 controls]; P<.002) than did control men.
Within 10 individual dads with frequent samples before and after the birth,
the percentage of samples with detectable estradiol was lower during the
month before the birth than during the month after (51% vs 71%; P=.02), and
cortisol concentration was increased in the week before the birth (to a mean
of 0.16 µg/dL). In each of 13 dads providing frequent samples, testosterone
concentration and variance were low immediately after the birth (no change
from previous levels in 5, decrease after prebirth increase in 3, and
decrease relative to all other times in 5).
? Conclusions: In this population of Canadian volunteers attending prenatal classes, expectant fathers had lower testosterone and cortisol levels and a
higher proportion of samples with detectable estradiol concentrations than
control subjects. Individual patterns of testosterone variance relative to
the birth and estradiol and cortisol concentrations immediately before the
birth may be worthy of further investigation. The physiologic importance of
these hormonal changes, if any, is not known. However, they are hormones known to influence maternal behavior.
ja nämä muutokset näyttävät moduloivan osin pysyväisluonteisen ja
irreversibiilin muutoksen miehen elimistössä.
Seifritz, E., Esposito, F., Neuhoff, J. G., Mustovic, H., Dammann, G.,
Bardeleben, U. v., et al. (2003). Differential Sex-Independent Amygdala
Response to Infant Crying and Laughing in Parents versus Nonparents.
Biological Psychiatry, 54, 1367?1375.
Background: Animal and human studies implicate forebrain neural circuits in maternal behavior. Here, we hypothesized that human brain response to emotional stimuli relevant for social interactions between infants and
adults are modulated by sex- and experience-dependent factors.
Methods: We used functional magnetic resonance imaging and examined brain response to infant crying and laughing in mothers and fathers of young children and in women and men without children.
Results: Women but not men, independent of their parental status, showed
neural deactivation in the anterior cingulate cortex, as indexed by
decreased blood oxygenation level? dependent signal, in response to both
infant crying and laughing. The response pattern changed fundamentally with parental experience: in the amygdala and interconnected limbic regions, parents (independent of sex) showed stronger activation from crying, whereas nonparents showed stronger activation from laughing.
Conclusions: Our data show sex- and experience-dependent modulation of brain response to infant vocalizations. Successful recognition and evaluation of infant vocalizations can be critical for bonding mechanisms and for offspring well-being and survival. Thus, the modulation of responses by experience seems to represent an adaptive mechanism that can be related to reproductive fitness.
Recognizing and evaluating infant vocalizations and discriminating between
crying and laughing are fundamental operations that caregivers of young
children must carry out. In animals, converging evidence demonstrates the importance of parental care for offspring fitness on behavioral,
physiologic, and molecular levels (Meaney 2001). Because securing offspring survival is an important element underlying evolutionary selection, it is likely that specific brain mechanisms have developed to subserve these operations. Animal studies have shown that the mammalian forebrain plays a particularly important role in the expression of reproductive physiology and behavior. These are fundamentally different in female and male animals and
are reflected in functional and morphologic sex differences in neural
forebrain circuits (Simerly 2002). The pivotal role of the forebrain in
mammals is further supported by its involvement in the regulation of
specific behaviors during nursing and maternal care of offspring (Champagne
et al 2001; Sheehan and Numan 2002). For instance, the thalamocingulate
division of the forebrain, which has no counterpart in evolutionarily older
species, such as reptiles, is believed to have evolved in parallel with
social behaviors related to the development of familial acculturation, which
are established to a large extent through audiovocal communication (MacLean
1985). The perception of emotional information in species-specific
communication sounds of nonhuman mammals?involved in securing emotional
bonding and social interactions? depends at least partially on
thalamocingulate neural circuits, both in parents (Murphy et al 1981) and
offspring (Braun and Poeggel 2001).
Casanova, G., Domanic, J., McCanne, T., & Milner, J. (1994). Physiological
responses to child stimuli in mothers with and without a childhood history
of physical abuse. Child Abuse & Neglect, 18, 995-1004.
Pretending to be certain about propositions for which no evidence is even conceivable—is both an intellectual and a moral failing. —Sam Harris