Roger J. Kittok

Testosterone, and winning and losing in human competition

Testosterone and cortisol were measured in six university tennis players across six matches during their varsity season. Testosterone rose just before most matches, and players with the highest prematch testosterone had the most positive improvement in mood before their matches. After matches, mean testosterone rose for winners relative to losers, especially for winners with very positive moods after their victories and who evaluated their own performance highly. Winners with rising testosterone had higher testosterone before their next match, in contrast to losers with falling testosterone, who had lower testosterone before their next match. Cortisol was not related to winning or losing, but it was related to seed (top players having low cortisol), and cortisol generally declined as the season progressed. These results are consistent with a biosocial theory of status.

Selection for components of reproduction in swine

Abstract The response per generation to 10 generations of mass selection for ovulation were 0.49 ova, −1.6% in embryo survival and 0.06 piglets per litter at birth. Line differences (select-control) in generation 9 and 10 gilts and sows ranged from 3.4 to 5 ova. Control line gilts and sows had 5.4 to 10.6% higher embryo survival to days 30 and 70 of gestation than did select line females. One generation of random selection followed by four generations of litter size selection, selection for decreased age at puberty or relaxed ovulation rate selection in the high ovulation rate line has resulted in lines that differed from the control line in litter size at birth by 0.78 ± 0.22, 0.37 ± 0.39 and 0.84 ± 0.52 pigs per litter at first, second and third parity, respectively. These results were used to derive a selection index to increase litter size by selection for its components (ovulation rate, OR, and embryo survival, ES). A technique of selection based on laparotomy to increase the number of females tested with a given set of farrowing places is presented. Rate of response in LS from use of the selection index, I = 10.6 OR + 72.6 ES, in a population of 40 farrowing females and 15 males per generation, is expected to increase litter size 2.5 times faster than selection on LS due to higher selection intensity and optimum emphasis on the component traits.

Secretion of gonadotrophins change during the luteal phase of the bovine oestrous cycle in the absence of corresponding changes in progesterone or 17β-oestradiol

Abstract The hypothesis in the present study was that changes in circulating luteinizing hormone (LH) and follicle stimulating hormone (FSH) would occur during the luteal phase of the oestrous cycle (Days 4–19; Day 0, day of behaviourial oestrus) that were not related to corresponding changes in concentrations of progesterone and 17β-oestradiol. The stage of the oestrous cycle of cows (n = 18) was synchronised to obtain cows that were on alternate days of the cycle. Blood samples were collected every other day at 15 min intervals for 12 h from all cows: Days 4, 6, 8, 10, 12, 14, 16, 18 (n = 9) and Days 5, 7, 9, 11, 13, 15, 17, 19 (n = 9). Concentrations of LH, FSH, 17β-oestradiol and progesterone were determined in these samples. Data were compared across days to determine when significant changes occurred in concentrations or patterns of secretion of the gonadotrophins and ovarian steroid hormones during the oestrous cycle. There were significant changes in mean concentrations of FSH in circulation between Days 6 and 12. The most striking changes in secretion of gonadotrophins that could not be explained by changes in gonadal steroids were the fluctuations in amplitude of LH pulses between Days 7 and 12. Amplitude of LH pulses increased between Days 7 and 11 and subsequently decreased between Days 11 and 12 of the oestrous cycle. Some changes in gonadotrophin secretion that occurred in the present study can be explained by fluctuations in concentrations of progesterone and 17β-oestradiol in circulation. Other changes cannot be explained by fluctuations in circulating concentrations of these steroids. We accept our hypothesis because the concomitant changes in mean concentration of FSH between Days 6 and 11 and amplitude of LH pulses between Days 7 and 12 of the bovine oestrous cycle cannot be explained by changes in circulating concentrations of progesterone and 17β-oestradiol.

Frequency of luteinizing hormone pulses and circulating 17β-oestradiol concentration in cows is related to concentration of progesterone in circulation when the progesterone comes from either an endogenous or exogenous source

Abstract The present study was designed to test whether progesterone from exogenous and endogenous sources modulates the frequency of luteinizing hormone (LH) pulses in a differential fashion. Our working hypotheses were: (1) the frequency of secretion of LH pulses and concentration of 17β-oestradiol in circulation would be directly related to circulating concentration of progesterone; (2) progesterone from an exogenous source would have a different effect on frequency of LH pulses and circulating concentration of 17β-oestradiol than progesterone from an endogenous source. Cows were treated with graded doses of PGF 2α or progesterone to result in varying concentrations of progesterone in circulation from endogenous and exogenous sources. Treatment with PGF 2α resulted in concentrations of circulating progesterone among animals in this group that ranged from 0.5 to 10.9 ng ml −1 of plasma. Treatment with progesterone resulted in circulating concentrations of progesterone among animals in this group that ranged from 0.8 to 11.8 ng ml −1 of plasma. Concentrations of progesterone in circulation and frequency of LH pulses were negatively correlated ( r = −0.59) in cows with functional corpora lutea and in cows treated with progesterone without corpora lutea ( r = −0.62). The frequency of LH pulses had the same relationship to the varying concentrations of progesterone in both treatment groups. Cows with higher progesterone levels had fewer LH pulses and cows with lower progesterone had a greater frequency of LH pulses. Mean circulating concentrations of 17β-oestradiol also had the same relationship with varying concentrations of progesterone in both treatment groups. Cows with higher progesterone levels had lower 17β-oestradiol and cows with lower progesterone had higher 17β-oestradiol levels. The results indicate that there is a direct relationship between circulating concentration of progesterone, frequency of LH pulses and circulating concentration of 17β-oestradiol. In addition, progesterone modulates the frequency of release of LH pulses from the pituitary and circulating concentration of 17β-oestradiol in a similar fashion when coming from either an endogenous or exogenous source.

Gonadotropin secretion and development of ovarian follicles during oestrous cycles in heifers treated with luteinizing hormone releasing hormone antagonist

The hypothesis tested was that reduced LHRH stimulation of the anterior pituitary would lead to attenuated development of ovarian follicles as a result of reduced gonadotropin secretion during oestrous cycles of cattle. Twenty heifers were randomly assigned to be treated ( n = 5/treatment) with an antagonist to LHRH (LHRH-Ant) 1) from Day 2 to 7 (Day 0 = behavioural oestrus), 2) Day 7 to 12, 3) Day 12 to 17, 4) or serve as untreated control animals. LHRH-Ant suppressed LH pulses of heifers in all treatment groups from treatment initiation through Day 17 as compared with untreated control heifers [Peters et al., 1994. Luteinizing hormone has a role in development of fully functional corpora lutea (CL) but is not required to maintain CL function in heifers. Biol. Reprod., 51 (1994) 1248-1254]. Circulating concentration of FSH from Day 8 to 10 of the oestrous cycle did not increase in heifers treated with LHRH-Ant from Day 2 to 7 or Day 7 to 12; however, there was increased (P < 0.05) FSH from Day 8 to 10 of the oestrous cycle in heifers treated with LHRH-Ant from Day 12 to 17 and control heifers. Compared with control heifers, heifers treated with LHRH-Ant from the Day 2 to 7 had suppressed (P < 0.05) size and persistence of the first and second dominant ovarian follicles. Heifers treated with LHRH-Ant from Day 7 to 12 had suppressed size (P < 0.05 and tended (P < 0.10) to have a shorter persistence of the second dominant ovarian follicle compared with control heifers. Heifers treated with LHRH-Ant from Day 12 to 17 had a similar (P > 0.10) size and persistence of dominant ovarian follicles but had reduced (P < 0.10) numbers of large follicles compared with control heifers. Heifers treated with LHRH-Ant from Day 2 to 7 had lower (P < 0.01) concentrations of 17 beta-oestradiol during the treatment period and tended (P < 0.10) to have lower concentrations of 17 beta-oestradiol from Day 7 to 12 of the oestrous cycle compared with control heifers. Heifers treated with LHRH-Ant from Day 7 to 12 or Day 12 to 17 had similar (P > 0.10) circulating LH concentrations of l7 beta-oestradiol compared with control heifers. Reduced LHRH stimulation of the pituitary from Day 2 to 12 of the oestrous cycle and the resulting modulation in circulating LH and FSH led to suppressed ovarian follicular development and oestradiol secretion. After Day 12 of the oestrous cycle, reduced LHRH stimulation of the anterior pituitary did not lead to altered ovarian follicular development to the extent as reduced LHRH stimulation before Day 12 although pulsatile release of LH was similarly suppressed by treatment with the LHRH-Ant.

Influence of prepubertal ovariectomy and estradiol replacement therapy on secretion of luteinizing hormone before and after pubertal age in heifers

Abstract Secretion of luteinizing hormone (LH) and effects of estradiol were evaluated during and after the prepubertal decline in negative feedback of estradiol on secretion of LH. Prepubertal heifers (269 ± 4 days of age; n=10) were ovariectomized on February 6, 1981 (Day 0). Five ovariectomized heifers were administered a subcutaneous implant on Day 0 which provided physiological serum concentrations of estradiol (OVX-E 2 ). The remaining 5 heifers were not implanted (OVX). A second estradiol implant was administered to OVX-E 2 heifers on Day 164 (n=3) or Day 206 (n=2) of the study. Blood samples were collected sequentially (every 12 min for 8 hr) at approximately two week intervals from Days 0 to 232 of the experiment. The experimental period spanned from approximately 100 days before (269 days of age) to 100 days after (501 days of age) the expected age at puberty. Mean serum concentration of LH and frequency of LH pulses increased rapidly from Days 0 to 36 in OVX heifers and were followed by a further gradual rise in pulse frequency (Day 50 to 232) and a reciprocal decline in mean LH and pulse amplitude. The rapid post-ovariectomy increase in secretion of LH was blocked by estradiol in OVX-E 2 heifers. All characteristics (mean, frequency and amplitude) of secretion of LH increased gradually during the experimental period in OVX-E 2 heifers (Days 0 to 232). Mean concentration and amplitude of pulses were higher in OVX-E 2 than in OVX heifers by Days 148 and 134, respectively. These differences were maintained for the remainder of the experimental period. No acute effects of the second estradiol implant on secretion of LH were observed in OVX-E 2 heifers. Results of this study indicate that long-term changes in secretion of LH occur following prepubertal ovariectomy in heifers and suggest that the previously documented prepubertal decline in negative feedback of estradiol on secretion of LH is followed by a period of positive feedback after pubertal age is surpassed.

Concentrations of gonadotropins, estradiol and progesterone in sows selected on an index of ovulation rate and embryo survival

The objective of this study was to determine concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), progesterone (P4) and 17beta-estradiol (E2) in sows from a line selected on an index which emphasized ovulation rate (Select) and from a control line. A further classification of the sows in each line was made according to the estimated number of ovulations during an estrous cycle. Sows in the Select line were ranked into a high (HI) or low group (LI) when their estimated number of ovulations were 25 or more and 14 to 15, respectively. Sows of the control line were classified into groups as high (HC) or low (LC) when the estimated values for ovulation rate were 14-15 and 8-9 ovulations, respectively. Blood samples were collected every 12 h during a complete estrous cycle and samples were analyzed for concentrations of FSH and LH. Samples collected every 24 h were assayed for P4 and E2. Mean concentrations of FSH, LH, P4 and E2 did not differ (P > 0.10) between lines or between HI and LI or HC and LC groups. Selection of pigs for ovulation rate and embryonal survival did not affect concentrations of FSH, LH, P4 and E2 in sows during the estrous cycle.

Effects of suckling and low doses of estradiol on luteinizing hormone secretion during the postpartum period in beef cows

Abstract An experiment was conducted to test if suckling acutely suppressed circulating levels of LH during the postpartum period in beef cows. In addition, the influence of exogenous administration of low concentrations of estradiol on LH secretion during the postpartum period was evaluated. Twelve mature cows were randomly assigned before parturition to one of three treatments. Four intact cows were used as controls (INT). Eight cows were ovariectomized within the first 7 days following parturition. Four of these cows received a silastic 17β-estradiol implant subcutaneously at the time of ovariectomy (OVX-E); the remaining four cows received no further treatment (OVX). All cows were allowed to nurse one calf for 30 min daily between 1200 and 1230 hours for the duration of the experiment. Blood samples were collected at 12 min intervals for 6 hr before and 6 hr after suckling on days 9, 30, 44 and 58 postpartum. Mean interval (mean ± SE) to the first increase in peripheral progesterone concentrations indicative of the onset of ovarian luteal activity was detected in INT cows 37 ± 4.9 days postpartum. An acute effect of suckling on LH secretion did not occur in INT and OVX cows but mean LH concentrations were reduced in OVX-E cows following suckling on days 44 and 58. Mean LH concentrations remained low in INT cows; whereas, in OVX and OVX-E cows LH concentrations increased linearly (P

Circulating concentrations of 17-estradiol influence pattern of LH in circulation of cows☆

The objective of the research was to determine the relationship between circulating 17 beta-estradiol (E2) and secretion of luteinizing hormone (LH) in cows. A second objective was to determine if response to E2 was influenced by interval between ovariectomy and the start of E2 treatment. Thirty-one nulliparous cows 3 yr of age were randomly assigned to a 2 x 4 factorial arrangement of treatments. Sixteen cows were ovariectomized at 18 mo of age (long term), and the other 15 cows were ovariectomized at 36 mo of age (short term). At the time of ovariectomy of cows in the short term group, 11 cows in the short term group and 12 cows in the long term group were implanted subcutaneously with 1, 2 or 4 polydimethylsiloxane capsules containing E2. The other eight cows served as non-implanted controls (n = 4-short term, n = 4-long term). All cows were fitted with jugular vein catheters on day 29 of treatment, and on day 30 blood samples were collected at 12-min intervals for 6 hr. At the end of 6 hr, luteinizing hormone-releasing hormone (LHRH) was administered and blood sampling continued at 12-min intervals for an additional hour. Serum was analyzed for LH and E2. Variables of LH secretion analyzed were mean concentration, frequency of pulses, amplitude of pulses and maximum concentration after LHRH. There were no significant interactions for any of the variables of LH among cows ovariectomized for the long and short term. There was a significant linear increase in mean concentration of LH with increased circulating concentration of E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of 17β-estradiol on the preovulatory surge of LH in the bovine female☆

The hypothesis tested was that increasing concentration of 17beta-estradiol (E(2)) subsequent to luteolysis stimulates the preovulatory surge of LH and that a decline in E(2) after the initial rise is not necessary to trigger the preovulatory surge of LH in the bovine female. Beef cows were synchronized to Day 16 of the estrous cycle. At Hour 0, all cows were ovariectomized and received one of four E(2) treatments: 1) luteal phase E(2) (LE; n=5), 2) increasing then decreasing E(2) (DE; n=5), 3) increasing and subsequent maintenance of high E(2) (IE; n=4), and 4) no E(2) (NE; n=3). Cows in the LE group received one E(2) implant at Hour 0 which provided low concentrations of E(2). Cows in the DE group received one E(2) implant at 0, 8, 16, 24, 32 and 40 hours; implants were subsequently removed at 8-hour intervals, thus mimicking the preovulatory rise and fall of E(2). Cows in the IE group were treated with the same regimen of E(2) implants as cows of the DE group, except that no E(2) implants were removed. Blood samples were collected at Hour 0 and at hourly intervals from Hour 2 through 80, for serum LH and E(2) quantification. The number of cows responding with a surge of LH was 0/3, 0/5, 4/5 and 3/4 for the NE, LE, DE and IE treatments, respectively. The proportion of cows responding with an LH surge was different (P<0.01) when data for cows in the NE and LE groups were pooled and compared with the pooled data of cows in the DE and IE groups. The mean time of the LH surge was not different (P>0.80) for cows responding with an LH surge (DE and IE treatments). Thus, increased levels of E(2) greater than luteal phase concentrations are needed to initiate preovulatory surges of LH, and it appears that concentrations of E(2) need to reach a certain level but do not need to decrease after this initial rise to stimulate a surge release of LH.