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PubMed1996

Chemical and behavioral stimulation from females accelerates recrudescence in male Syrian hamsters exposed to short days.

Interaction with female hamsters maintained under long photoperiods (LP) accelerates behavioral recrudescence in short photoperiod (SP) males. In this experiment, the authors investigated the effects of various types of female sociosexual cues on different measures of reproductive recrudescence in the male. Five groups of SP males were exposed to different female cues for 3 weeks (Weeks 12 to 15). At Week 16, males were allowed to interact with estrus females; behavioral, physiological, and fecundity measures were monitored. The results show that all measures responded in a pseudo-dose-dependent manner to the different female cues presented. SP males not exposed to any female cues and those exposed to distal visual, auditory, and volatile pheromonal cues from estrus females did not copulate, deposit sperm, or impregnate estrus females presented to them at Week 16. SP males allowed direct access to the bedding of estrus females showed marked improvements on these same reproductive measures by Week 16. However, SP males that interacted with LP females between Weeks 12 and 15 showed the greatest level of reproductive function at Week 16. These results show that the type of female sociosexual stimulation is important in accelerating reproductive recrudescence; whereas interaction with LP females may be important in accelerating behavioral recrudescence, both interaction with and exposure to the bedding of LP females may be important in accelerating physiological and reproductive success measures.

Animals↗
PubMed2004

Autodissemination of the entomopathogenic fungus Metarhizium anisopliae amongst adults of the malaria vector Anopheles gambiae s.s.

BACKGROUND: The entomopathogenic fungus Metarhizium anisopliae is being considered as a biocontrol agent for adult African malaria vectors. In the laboratory, work was carried out to assess whether horizontal transmission of the pathogen can take place during copulation, as this would enhance the impact of the fungus on target populations when compared with insecticides. METHODS: Virgin female Anopheles gambiae sensu stricto were exposed to conidia whilst resting on fungus-impregnated paper. These females were then placed together for one hour with uncontaminated males in proportions of either 1:1 or 1:10 shortly before the onset of mating activity. RESULTS: Males that had acquired fungal infection after mating indicate that passive transfer of the pathogen from infected females does occur, with mean male infection rates between 10.7 +/- 3.2% and 33.3 +/- 3.8%. The infections caused by horizontal transmission did not result in overall differences in survival between males from test and control groups, but in one of the three experiments the infected males had significantly shorter life spans than uninfected males (P < 0.05). CONCLUSION: This study shows that autodissemination of fungal inoculum between An. gambiae s.s. mosquitoes during mating activity is possible under laboratory conditions. Field studies are required next, to assess the extent to which this phenomenon may augment the primary contamination pathway (i.e. direct contact with fungus-impregnated targets) of vector populations in the field.

Animals↗
PubMed2005

Rapid decreases in preoptic aromatase activity and brain monoamine concentrations after engaging in male sexual behavior.

In Japanese quail, as in rats, the expression of male sexual behavior over relatively long time periods (days to weeks) is dependent on the local production of estradiol in the preoptic area via the aromatization of testosterone. On a short-term basis (minutes to hours), central actions of dopamine as well as locally produced estrogens modulate behavioral expression. In rats, a view of and sexual interaction with a female increase dopamine release in the preoptic area. In quail, in vitro brain aromatase activity (AA) is rapidly modulated by calcium-dependent phosphorylations that are likely to occur in vivo as a result of changes in neurotransmitter activity. Furthermore, an acute estradiol injection rapidly stimulates copulation in quail, whereas a single injection of the aromatase inhibitor vorozole rapidly inhibits this behavior. We hypothesized that brain aromatase and dopaminergic activities are regulated in quail in association with the expression of male sexual behavior. Visual access as well as sexual interactions with a female produced a significant decrease in brain AA, which was maximal after 5 min. This expression of sexual behavior also resulted in a significant decrease in dopaminergic as well as serotonergic activity after 1 min, which returned to basal levels after 5 min. These results demonstrate for the first time that AA is rapidly modulated in vivo in parallel with changes in dopamine activity. Sexual interactions with the female decreased aromatase and dopamine activities. These data challenge established views about the causal relationships among dopamine, estrogen action, and male sexual behavior.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2006

An orally active selective androgen receptor modulator is efficacious on bone, muscle, and sex function with reduced impact on prostate.

A number of conditions, including osteoporosis, frailty, and sexual dysfunction in both men and women have been improved using androgens. However, androgens are not widely used for these indications because of the side effects associated with these drugs. We describe an androgen receptor (AR) ligand that maintains expected anabolic activities with substantially diminished activity in the prostate. LGD2226 is a nonsteroidal, nonaromatizable, highly selective ligand for the AR, exhibiting virtually no affinity for the other intracellular receptors. We determined that AR bound to LGD2226 exhibits a unique pattern of protein-protein interactions compared with testosterone, fluoxymesterone (an orally available steroidal androgen), and other steroids, suggesting that LGD2226 alters the conformation of the ligand-binding domain. We demonstrated that LGD2226 is fully active in cell-based models of bone and muscle. LGD2226 exhibited anabolic activity on muscle and bone with reduced impact on prostate growth in rodent models. Biomechanical testing of bones from animals treated with LGD2226 showed strong enhancement of bone strength above sham levels. LGD2226 was also efficacious in a sex-behavior model in male rats measuring mounts, intromissions, ejaculations, and copulation efficiency. These results with an orally available, nonaromatizable androgen demonstrate the important role of the AR and androgens in mediating a number of beneficial effects in bone, muscle, and sexual function independent from the conversion of androgens into estrogenic ligands. Taken together, these results suggest that orally active, nonsteroidal selective androgen receptor modulators may be useful therapeutics for enhancing muscle, bone, and sexual function.

Administration, Oral↗
PubMed1976

Effect of surgical disconnection of the medial basal hypothalamus on postcoital reflex ovulation in the rabbit.

The effects of hypothalamic transections of varying lengths on reflex ovulation in the rabbit are reported. Circular cuts which surgically isolated the medial basal hypothalamus (MBH) from the remainder of the brain did not prevent copulation 4 to 24 h later, but did block reflex ovulation. On the contrary, hemicircular cuts of either the rostral, caudal or one lateral haf of the circular cut did not prevent reflex ovulation. These results suggest that coital stimuli reach the MBH through a diffuse network of fibers and that only very extensive deaferrentation of the MBH can cause blockade of ovulation in rabbits. These data are compared with results of other investigators in which anterior deafferentation of the MBH blocked reflex and spontaneous ovulation in rats.

Animals↗
PubMed1996

Sexual dimorphism in secretion of hypothalamic gonadotropin-releasing hormone and norepinephrine after coitus in rabbits.

Coital activation of the hypothalamo-hypophyseal ovarian axis (HOA) is well documented in rabbits, but coital excitation of the hypothalamo-hypophyseal testicular axis (HTA) is less well described. We and others have postulated that the response of the HOA to coitus, as characterized by a dramatic release of hypothalamic GnRH, may be mediated by an increase in norepinephrine (NE) neuronal activity. Herein, we studied selective HOA and HTA responses in New Zealand White rabbits before, during, and after coitus. Firstly, we determined the effects of microdialysis (mu D) and blood-sampling methods on plasma LH and testosterone (T) patterns in male rabbits during sexual performance. Subsequently, we compared the patterns of release in GnRH and norepinephrine (NE) from the arcuate nucleus-median eminence (AME) at 10-min intervals with changes in plasma LH levels in copulating male and female rabbits. Lastly, in 2.5-min AME mu D samples from females immediately after coitus, we measured NE and GnRH concentrations to determine whether NE release precedes that of GnRH. Tethered, freely moving rabbits were exposed to their partners for 10 min at the end of the third (10-min sampling for 5-7 h) or second (2.5-min sampling for 4 h) hour. Data from individuals that did not mate during the 10-min of pairing in the 3- to 7-h sampling trials were included as a control group (sham-mated). The results showed no changes (P > 0.05) in plasma LH and T in either mated (LH: pre, 0.13 +/- 0.08 ng/ml; post, 0.15 +/- 0.03 ng/ml; T: pre, 2.39 +/- 1.20 ng/ml; post, 0.85 +/- 0.26 ng/ml) or sham-mated males (LH: pre, 0.21 +/- 0.08; post, 0.25 +/- 0.10 ng/ml; T: pre, 1.46 +/- 0.51 ng/ml; post, 1.40 +/- 0.38 ng/ml). Likewise, coitus did not alter patterns of AME-NE (pre, 0.47 +/- 0.25; post, 0.56 +/- 0.25 ng/ml) and GnRH (pre, 0.61 +/- 0.45; post, 0.74 +/- 0.32 pg/ml) in mated or sham-mated males. The constant HTA activity during coitus in males appears to be independent of experimental manipulation per se because LH and T levels between mu D (0.18 +/- 0.05 and 1.72 +/- 0.85 ng/ml, respectively) and non-mu D (0.16 +/- 0.05 and 1.52 +/- 0.36 ng/ml, respectively) rabbits were not different (P > 0.05). In contrast to males, females displayed unambiguous and simultaneous increases in NE (P < 0.05) and GnRH (P < 0.01) release from the AME within 10-20 min after coitus; these elevated concentrations in mu D samples lasted for 3-4 h. Microdialysis NE levels averaged 0.02 +/- 0.01 ng/ml before mating, whereas postcoital values averaged 0.09 +/- 0.01 ng/ml. GnRH levels were 1.04 +/- 0.56 and 11.78 +/- 5.06 pg/ml before and after coitus, respectively. Concomitant increases in plasma LH levels were also observed after coitus in these female rabbits. Moreover, measurements of NE and GnRH in 2.5-min mu D samples revealed that the postcoital increase in NE preceded that in GnRH by 2.5-7.5 min (P < 0.05). The results suggest that neuroendocrine circuits in the two sexes of the New Zealand White rabbit respond differently to genital stimulation. In male rabbits, coitus does not alter patterns of AME NE or GnRH secretion, nor does it change the circulating levels of plasma LH or T. Conversely, in females, coitus induces the rapid release of hypothalamic NE, GnRH, and pituitary LH. The increase in coitally induced NE occurs before the rise in GnRH, which supports the hypothesis that NE is a critical neurochemical in coital activation of GnRH neurons.

Analysis of Variance↗
PubMed1977

The mechanism for co-ordinating metachronal limb movements between joined male and female Artemia salina during precopulatory behaviour.

Male and female Artemia salina swim in tandem pairs before copulation and during this period the metachronal rhythms of the individuals are entrained. Artemia entrain to pulsatile water stimulation of the head at frequencies between 4 and 6 Hz. The antennules are mechano-sensitive. Antennular responsiveness to phasic input is very probably the actual mechanism by which interorganism co-ordination is achieved, as mechano-stimulation of other Artemia structures, electro-stimulation and photo-stimulation are ineffective modes of entraining metachronal movements.

Animals↗
PubMed2005

Morphometric analysis of a population of diplopods of the genus Rhinocricus Karsch, 1881.

Diplopods belonging to the subclass Helminthomorpha may present one or both leg pairs of the seventh diplosegment modified into structures that aid copulation, called gonopods. These structures are used as a taxonomic trait for the description of most species. In the genus Rhinocricus these structures are closely similar, so that it is difficult to distinguish species only on the basis of this trait. Two species, R. padbergi and R. varians, are found in the same habitat and present gonopods practically identical in shape; together they present a broad colour gradient, ranging from dark brown to light beige. Morphometric data for individuals of the experimental group were submitted to ANOVA and MANOVA, using Hotelling-Lawley Trace and generalized Mahalanobis distances (D2) tests. The results demonstrated a relationship between size and colour, with darker individuals being larger. On the basis of this preliminary analysis, we may suggest that the two species are distinct since dark individuals are distant from medium- and light-coloured individuals according to the D2 values. This seems to indicate a possible polymorphism of individuals belonging to R. padbergi which present close proximity in the values obtained. In all analyses, we observed that the main variables were diameter, length and telson size.

Animal Structures↗
PubMed1976

Plasma concentrations of testosterone in the developing ram in different social environments.

Plasma testosterone profiles were determined by taking frequent blood samples at intervals from birth to 21 months of age from rams reared in isolation, in an all-male group and in a mixed-sex group. The testosterone pattern was not modified by these different social environments. The ability of the ram to copulate when first exposed to an oestrous ewe, apparently a maturational process, was also independent of social rearing. At birth plasma testosterone levels were detectable but low, they were higher at 10 and 16 weeks of age and showed a marked rise by 26 weeks, coincident with the time of puberty. Depressive effects of season on testosterone profiles occurred during the 2nd year of life but not the 1st year.

Age Factors↗
PubMed1976

Effects of ewe proximity on peripheral plasma testosterone levels and behaviour in the ram.

Groups of yearling and immature rams were kept for 6 months during the breeding season either adjacent to or apart from ovariectomized ewes in which oestrus was induced by hormone therapy. The older rams kept near ewes were found to have larger testes, higher plasma testosterone levels and greater sexual and aggressive activity, although the immature animals showed no response. Plasma testosterone concentration was also found to increase after copulation in some animals.

Age Factors↗
PubMed1981

Observations on the induction of ovulation and expulsion of uterine eggs in the mink, Mustela vison.

In 8 of 12 mink paired for the first time, pairing alone induced ovulation and a short (5 min) interrupted mating led to 8/8 ovulating with normal numbers of corpora lutea. However, in already mated mink, a short mating (Day 7) failed completely or partly (reduced number of ovulations) to induce ovulation. In mink which refused to mate, hCG consistently induced ovulation. In already mated mink (Day 0) a later mating (Day 7), even if interrupted after 5 min, led to expulsion of the first set of eggs, approximately 50% of which were 'lost' by Day 4 and virtually 100% by Day 6. This effect was not produced by pairing without intromission or by treatment with hCG to induce ovulation. It is concluded that copulation is primarily responsible for the loss of eggs from the uterus, although the exact mechanism remains obscure.

Animals↗
PubMed1986

Morphometric analysis of follicular dynamics in pregnant and pseudopregnant rats.

Morphometric analysis of the follicle population greater than or equal to 100 X 10(5) micron 3 or a mean diameter of greater than or equal to 275 micron and assessment of the rate of atresia in ovaries of pregnant and pseudopregnant rats revealed no evidence for the presence of rhythmic follicular maturation during the prolonged dioestrous period. During the first 4-5 days of the dioestrous period, follicles developed to preovulatory size (volume class 5, i.e. greater than or equal to 1000 X 10(5) micron 3 = diam. greater than or equal to 576 micron) reaching the normal number of ovulating follicles in cyclic animals in pregnant rats, but only half that number in pseudopregnant rats. These follicles collapsed on the 5th to 8th days of the dioestrous period and full numbers of preovulatory follicles were not found thereafter until the end of pregnancy and pseudopregnancy. Follicles of smaller sizes (classes 1-4: 100-999 X 10(5) micron 3), however, were present throughout the prolonged dioestrous period. The rate of atresia in the follicle population had increased by the 2nd day and remained from then on at 26.5 +/- 4.5% in the pregnant and 34.3 +/- 1.9% in the pseudopregnant rats. Atretic follicles in the advanced stages of atresia, mostly derived from follicles of classes 1-3, persisted and accumulated at the end of the dioestrous period. The continuous presence of follicles and the constant rate of atresia during the dioestrous period indicate continuous follicular replacements and refute the idea of follicular quiescence during pregnancy and pseudopregnancy. Copulation and electrical stimulation of the cervix seemed to reduce the formation of the new crop of follicles the next morning and the pool of small antral follicles normally maintained after oestrus in cyclic animals. Nevertheless, the smaller crop and pool of follicles seemed able to provide a sufficient number of preovulatory follicles at the end of pregnancy and a sufficient number of ovulations at the end of pseudopregnancy.

Animals↗
PubMed1990

Copulatory behaviour and coagulum formation in the female reproductive tract of the Australian hopping mouse, Notomys alexis.

Hopping mice were examined to study two interrelated questions: (1) when groups of adults of both sexes are kept together in one cage in the laboratory is there evidence that the females copulate with only one male, and (2) is a copulatory plug formed in the female tract after ejaculation? The findings indicate that a female will sometimes lock with more than one male in the group during an oestrous period induced by administration of exogenous gonadotrophins, and that a small 'plug' of soft material forms post coitum in the more caudal parts of the female tract. Individuals of this species, therefore, do not appear to be strictly monogamous, at least in this artificial laboratory situation. Although a coagulum is formed, this is quite different from the typical hard copulatory plug that occurs in common laboratory murids; it may possibly reduce sperm backflow from the lower region of the female reproductive tract.

Animals↗
PubMed1993

Prediction of fertility by mating latency and photoperiod in nulliparous and primiparous meadow voles (Microtus pennsylvanicus).

Mating behavior and litter production of female meadow voles (Microtus pennsylvanicus) housed in long (14 h light: 10 h dark; long day; LD) or short (10 h light: 14 h dark; short day; SD) photoperiods were monitored to determine whether the reduced birthrate of SD females resulted from a lack of copulation. All females mated, but fewer SD females gave birth. LD and SD females fell into three distinct groups based on mating latency. The rapid onset group (RO) mated between 7 min and 9 h after pairing, the intermediate onset group (IO) mated between 16-44 h and the late onset group (LO) mated after 58-262 h of male contact. Sixty-seven per cent of LD females were assigned to group RO, 27% to IO, and 6% to LO. In contrast, 30% of SD females were assigned to group RO, 35% to IO and 35% to LO. Fertility was predicted by mating latency. Sixty-nine per cent of RO, 93% of IO and 33% of LO animals gave birth. In a further experiment, a small-mouthed cup was added to the environment to serve as an escape for females wishing to avoid mating. Although females did not use the cup to escape male approaches, mating occurred in only 66% of SD females, but was observed in all LD females. In a final experiment, mating latency and litter production were recorded in primiparous LD and SD females initially observed in the first experiment. Group LO was eliminated in parous females; all primiparous LD and SD females mated within 48 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The urethral glands of male mice in relation to depletion of secretory granules upon mating.

The present study describes the effects of mating on urethral gland acinar cells in male mice. Histological and morphometric analysis demonstrated that there was a depletion of secretory granules in the urethral glands during mating. However, no change occurred in the rough endoplasmic reticulum containing tubular elements. The results indicate that the urethral glands are functional during mating. The timing of their granule depletion suggests that urethral gland secretions may contribute to the formation of semen or the copulation plug.

Animals↗
PubMed2001

Ultrasound and endocrine evaluation of the ovarian cycle and early pregnancy in the Sumatran rhinoceros, Dicerorhinus sumatrensis.

Longitudinal ultrasound and endocrine evaluations were conducted in two adult female Sumatran rhinoceroses (Dicerorhinus sumatrensis) over a period of 12-22 months to learn more about their reproductive physiology. Rectal ultrasonography was conducted to monitor ovarian activity. Blood samples were collected and analysed for progesterone and LH, and faecal samples were analysed for progestin metabolites. One female showed cyclic ovarian activity during the study period, whereas the other female showed no evidence of ovarian activity. The cyclic Sumatran rhinoceros appeared to be an induced ovulator, the first of its kind reported within the Perrisodactyla. Ultrasound examinations of the ovaries revealed the formation of anovulatory haemorrhagic follicles when the animal was not mated. These follicles appeared to undergo varied degrees of luteinization that resulted in irregular faecal progestin profiles. When allowed to mate, the female showed a 21 day reproductive cycle that was reflected in both faecal progestin and serum progesterone profiles. The concentration of serum LH was baseline before mating, increased approximately 30-fold within 1-2 h of intromission and returned to baseline within 22 h. Ovulation occurred within 46 h of copulation. The female conceived three times during the study. Pregnancy was detected using ultrasonography 14-16 days after mating, and the concentration of both serum progesterone and faecal progestins remained high. Early embryogenesis appeared to be similar to that in horses. However, each pregnancy terminated unexpectedly within the first 3 months of gestation. This study demonstrates the important role that basic research and reproductive technology can play in developing a natural breeding programme for an endangered animal in captivity.

Abortion, Spontaneous↗
PubMed2003

Mating-induced cumulus-oocyte maturation in the shrew, Suncus murinus.

The musk shrew, Suncus murinus, is an induced ovulator, the cumulus oophorus of which is unusual in several respects: it has no matrix, it always induces the acrosome reaction and it appears to be essential for fertilization. The present study documents distinctive features of the cumulus oophorus before and after ovulation, and of copulation-induced maturation of the ovulatory follicle, which has no antrum. In unmated females, potentially responsive ovarian follicles are distinguishable from large secondary follicles by differentiation of the granulosa into outer and inner cell layers, the latter being characterized particularly by intracellular glycogen deposits. The average number of responsive follicles equates with the number that ovulate. By about 10 h after mating, meiosis has reached metaphase II, with extrusion of the first polar body. Coincidentally, a cavity has developed between the inner and outer follicular layers, demarcating the smaller cells of the granulosa from the glycogen-rich cells of the cumulus oophorus. Subsequently, the glycogen becomes restricted primarily to the inner cumulus, and the corona cells began to retreat from the zona pellucida surface to form an unusual very distinct perizonal space that is clearly evident at the time of ovulation. The cumulus is stabilized by gap and tight junctions, and presents a smooth external surface that appears to initiate the acrosome reaction. After fertilization, at which time the zona pellucida becomes more resistant to both trypsin and dithiothreitol, the cumulus develops intercellular lacunae, and is eventually discarded about 15 h after ovulation.

Acrosome Reaction↗
PubMed2004

Semen-induced luteal phase and identification of a LH surge in the koala (Phascolarctos cinereus).

The koala ovulates in response to mating. The purpose of this study was to document the LH surge induced by copulation and to investigate the potential roles of mechanical stimulation of the urogenital sinus and deposition of semen in induction of the luteal phase. In experiment 1, serial blood samples from four koalas that underwent normal mating showed elevated concentrations of LH approximately 24-32 h post-coitus. There was no corresponding elevation in LH in koalas (n=4) that were exposed to the presence of a male but received no physical contact. In experiment 2, koalas on day 2 of oestrus were exposed to one of the following treatments (n=9 per group): artificial insemination with 1 ml 0.9% sterile saline (control group), insemination with 1 ml koala semen, stimulation of the urogenital sinus with a purpose built glass rod (designed to mimic the action of the penis during natural mating) and urogenital stimulation with the glass rod followed by insemination of 1 ml koala semen. Confirmation of a luteal phase was based on evidence of a prolonged return to oestrus, parturition and/or elevated progesterone concentrations. Insemination of saline (0/9) and urogenital stimulation (0/9) failed to induce a luteal phase. Insemination of semen without glass rod stimulation resulted in a luteal phase in 4/9 koalas, three of which gave birth. Insemination of semen in combination with urogenital stimulation produced a luteal phase in 7/9 koalas, four of which gave birth. Semen had a significant effect on induction of the koala luteal phase (P <0.001) but glass rod stimulation had no such effect (P=0.335). It was concluded that semen must be involved in the induction of a luteal phase in the koala. The results presented in this study will serve to improve optimal timing and induction of ovulation for artificial insemination in the koala.

Animals↗