Kaylan M. Schulz, Heather N. Richardson, Julia L. Zehr, Andrew J. Osetek, Tami A. Menard, and Cheryl L. Sisk. By: James Aliamus

Transcription

1 Kaylan M. Schulz, Heather N. Richardson, Julia L. Zehr, Andrew J. Osetek, Tami A. Menard, and Cheryl L. Sisk By: James Aliamus

2 - Original Article: Back to the future: The organizational activational hypothesis adapted to puberty and adolescence - The review article used these studies to establish that some male social behaviors are organized by pubertal hormones - It showed this by explaining how if this puberty- critical period of hormones is missed, even a prolonged period of testosterone replacement in adulthood doesn t normalize the hamsters. - Showed that levels of flank- marking, sexual behavior, and aggressive behavior are reduced in males in the hormones were not present during this critical period during puberty for the hamsters.

3 1) Gonadal Hormones during puberty masculinize behavioral responses to testosterone in adulthood. 2) Gonadal hormones during puberty defeminize behavioral responses to estrogen and progesterone. 3) Whether prolonged testosterone treatment or sexual experience could reverse the deficits in masculine behavior caused by the absence of Testosterone during puberty.

4 Animals: 18 day old Syrian Hamsters, all males - Two Groups of hamsters - Experimental Group: Surgically removed gonads before puberty - Control Group: Surgically removed gonads after puberty - Six weeks after the removal of their gonads, the hamsters were given a 3- week time- release testosterone pellet to circulate testosterone at adult physiological levels. - After a week had passed from the injection of the pellet, males behavior was tested with a receptive female.

5 - 18 male hamsters had their gonads removed before puberty, and 18 other male hamsters had their gonads removed after puberty. - 7 weeks post surgery, half of the subjects in each group were injected with both estrogen and progesterone, while the control groups were injected with just oil Females were ovariectomized after puberty, and then all groups (both male and female) were hormone- primed and tested for lordosis

6 - 18 males were gonadectomized before puberty, and 16 males were castrated as adults. - 6 weeks after surgery, all males were implanted with a 3- week time- release testosterone pellet. - The animals were then tested for the effect of sexual experience on responsiveness to testosterone

7 Graphs Light Gray: sexually inexperienced males that were gonadectomized before puberty (n=6) Dark Gray: Sexually inexperienced males that were gonadectomized after puberty (n=7) This graph shows the number of mounts and intromissions during a display of reproductive behavior with a receptive female 7 weeks post- gonadectomy, the rats were given a dose of testosterone for the week leading up to the introduction of the female hamster.

8 - Experiment 1: Hypothesis 1 was confirmed, it was shown that there is a critical period during puberty in which gonadal hormones masculinize behavioral responses in the hamsters to testosterone in adulthood. - Experiment 2: Hypothesis 2 was confirmed, males who didn t get gonadal hormones during period displayed significantly longer lordosis latencies than ovariectomized females and males who received gonadal hormones in puberty when given doses of estrogen and progesterone in adult life. - Experiment 3: This experiment showed that even an extended gonadal hormone dosage post puberty could make up for the critical period during puberty. However, it showed than sexually experienced hamsters displayed more mounts (but not intromissions or ejaculations) than sexually inexperienced hamsters.

9 - Strengths - Separate Experiments - Well organized, very exact instructions for reproduction of the experiment - Weaknesses - Workarounds (problem with manually stimulated lordosis tests, couldn t compare female and male GX behavior) - Small Sample Size

10 - Hormonal Determinants of the Development of Masculine and Feminine Behavior in Male and Female Rats - Found that although their gonads made a significant difference for their development (males will always mount if not gonadectomized at/before birth, and as long as given normal doses of natural hormones), but that behavioral sexual differentiation induced by hormones is best shown to be an inhibition to the potential to display behavior later in life

11 - Solid study, could use some improvement in structuring - Proved exactly what was quoted in the review article, almost word for word taken from the abstract. - Future Studies could follow up with larger test groups, could be used to think about possible follow ups with humans who are going through trouble transitioning between sexes, pre- puberty is probably best for overall quality of the transition if at all possible.

12 Original Study: Schulz, K., Richardson, H., Zehr, J., Osetek, A., Menard, T., & Sisk, C. (2003). Gonadal hormones masculinize and defeminize reproductive behaviors during puberty in the male syrian hamster. (Vol. 45, pp ). Follow up study: /abstract

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