C A Gallagher

Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

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Publications (3)11.41 Total impact

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    ABSTRACT: Male ferrets born in the laboratory received subcutaneous Silastic capsules containing either the aromatase inhibitor, androst-1,4,6-triene-3, 17-dione (ATD), the 5 alpha-reductase inhibitor, testosterone-17 beta-carboxylic acid (17 beta C), or no hormone, for 15 days beginning on the day of birth; an additional group of females received empty Silastic capsules. All ferrets were gonadectomized when 11 weeks of age and were subsequently tested for masculine sexual behavior after a latin-square sequence of treatments with subcutaneous Silastic capsules containing testosterone (T), estradiol (E), or dihydrotestosterone (DHT). After T, control males displayed significantly more neck gripping, mounting and pelvic thrusting than control females, and males treated neonatally with ATD or 17 beta C were no less responsive than control males. After DHT, little masculine sexual behavior was shown by any group. After E, the duration of mounting was significantly longer in control and ATD males than in control females or 17 beta C males. Subsequently, however, there were no differences between control and 17 beta C males on any parameter of masculine sexual performance, when they were retested sequentially after subcutaneous implantation of E followed by E + DHT. Additional groups of newborn male and female ferrets received subcutaneous capsules containing either ATD, 17 beta C, or no hormone and were killed on postnatal day 7. Administration of ATD, but not 17 beta C, strongly inhibited aromatase activity in the hypothalamus + preoptic area. In all groups, the formation of significantly inhibited cortical 5 alpha-reductase activity. Plasma concentrations of T were equivalent on postnatal day 7 in males given each of the neonatal treatments. These results suggest that behavioral masculinization in the male ferret results primarily from the neonatal action in brain of T itself, and not from its estrogenic or 5 alpha-reduced androgenic metabolites.
    Neuroendocrinology 02/1983; 36(4):277-84. · 3.54 Impact Factor
  • M J Baum, C A Gallagher, J T Martin, D A Damassa
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    ABSTRACT: Groups of female ferrets born in the laboratory received sc Silastic capsules containing testosterone (T), 5 alpha-dihydrotestosterone (DHT), 17 beta-estradiol (E), or no steroid for 15 days beginning on the day of birth; an additional group of male ferrets received empty sc capsules neonatally. All ferrets were gonadectomized at 11 weeks of age and were subsequently tested for masculine and feminine sexual behaviors while being treated consecutively over an 8-month period with several different gonadal steroids. The ability to display masculine sexual behavior was studied in the absence of replacement hormones and during a counterbalanced sequence of treatments with Silastic capsules containing T, E, or DHT. The maximal amount of neck grip, mount, and pelvic thrusting behavior displayed, regardless of adult endocrine treatment, was significantly greater in control male and neonatally T-treated females than in females that had received no hormone, E, or DHT neonatally. Animals in all five groups displayed equivalent increments in sexual receptivity in response to daily sc injections of increasing dosages of estradiol benzoate. Polyacrylamide gel electrophoresis of plasma collected from newborn female ferrets revealed no binding of either [3H]E or [3H]T, whereas two binding peaks were found for [3H]DHT. After the administration of androgen in adulthood, equivalent clitoral growth and ossification occurred in females given either T or DHT neonatally. These results suggest that in ferrets, behavioral masculinization occurs in response to neonatal exposure to T itself and not to its major neural metabolites, E and DHT. They also show that behavioral defeminization fails to occur in ferrets even after neonatal exposure to pharmacological amounts of E, T, or DHT.
    Endocrinology 10/1982; 111(3):773-80. · 4.72 Impact Factor
  • M J Baum, C A Gallagher
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    ABSTRACT: Daily SC injections of increasing dosages (0, 2, 4, 6, 8, or 10 μg/kg) of estradiol benzoate (EB) dissolved in sesame oil caused equivalent increments in acceptance quotients displayed by adult, gonadectomized male and female ferrets in response to a stimulus male. This finding provides further evidence that in the ferret behavioral defeminization normally is not a consequence of perinatal exposure to testicular androgen.
    Physiology & Behavior 05/1981; 26(4):751-3. · 3.16 Impact Factor