Reproductive activation

Interaction of vitamin D and its metaboUtes with sex hormones has been demonstrated, particularly ia birds ia which the egg-laying functions combine calcium needs and reproductive activity. The metaboUtes of vitamin D behave as hormones. As such, they play an active role ia the endocrine system, along with other hormones, to maintain the various body functions. Several biological influences of metaboUtes of vitamin D have been studied, including effects related to cancer (193—197), skin diseases (198—201), immunomodulatory effects (202,203), and Alzheimer s disease (204—206) (Fig. 9). 

The chemoreceptive mechanisms in amphibia are undoubtedly worthy of further analysis, not only for their own sake, but to provide clues as to the origination of advanced chemosignal systems. As noted above, a pheromonal signal from the mental gland acts as a courtship/ receptivity inducer. The plethodontid receptivity factor (PRF) (Chap. 3) despite its size (22 kD), seems to have been converted from its internal role as an inter-cellular cytokine, to an inter-individual coordinator of reproductive activity (Rollmann et al., 1999). Endocrine or... 

Marchlewska-Koj A. (1997). Sociogenic stress and reproductive activity in rodents. Neurosci Biobehav Rev 21, 699-703. 

No. 8 shot (72 mg) Mortality 24% in 4 weeks normal courtship and reproductive activities, but egg hatching significantly reduced lead residues elevated in kidney, liver, and bone 36... 

Menopause is biological evidence of aging in women. The absence of menstruation is clinical evidence of the inability of individual females to reproduce. However, what seems to be bad news is in fact proof that individual women can protect themselves. The reproductive process in the female is a very demanding one, and, consequently, nature has provided a mechanism to interrupt reproductive activity when biologic structures giving support to pregnancy enter the aging process. Conversely, in the male, whose participation in reproduction is limited both in time and resources, such a limitative mechanism does not exist. 

The acute toxicity of emorfazone was found to be equal to or less than that of aminopyrine depending on animal models used [45]. From chronic toxicity tests [46,47], safe doses of 30 mg/kg per day (rats) or 120 mg/kg per day (dogs) were deduced. In rats, no significant effects of (3) on the reproductive activity or newborn development were observed [48-50], nor were adverse effects on the embryos found when (3) was given to rabbits, rats or mice during the period... 

As a result, plants have a quite different focus to their reproductive activities from that of most familiar animals. From butterflies to bowerbirds, animals pour great energy into sexual rituals... 

For our purposes, oaks are important because they drop the acorns that determine how many white-footed mice successfully withstand the harsh winter months. Before winter arrives, however, a multitude of other factors has influenced the number of mice available to gather the acorns. One of these factors is the mice s reproductive activity, and this happens to be under the influence of some peculiar pheromones. Because they contribute to determining the number of mice, these chemicals also enter our story. They are airborne signals present in adult-mouse urine that affect the maturation and reproductive success of young female mice. 

The male reproductive system includes the two testes, ducts that store and transport the sperm to the exterior, and the glands that secrete into these ducts and the penis it also includes the hormones that integrate the reproductive activities. Basic details of the anatomy of the male reproductive system are given in Figures 19.1 and 19.2. 

A long-held view is that oestrogens are the hormones that control reproductive activity in the female and that androgens control the activity in the male. Although this is broadly the case, such a complete separation is too simple. For example, testosterone is secreted by the thecal cells in the ovary and although some is taken up by the granulosa cells for conversion to an oestrogen, some remains in the blood, where it has several roles (e.g. stimu-... 

The VNO is extremely important in mediating endocrine responses to primer pheromones. Puberty acceleration in female rats by male urine odors can be prevented by electrolytic damage to the vomeronasal nerve. Also, effects of male urine odor such as shortening of the estrus cycle (see Ch. 8) can be eliminated by section of the vomeronasal nerve, or bilateral electrocoagulation of the accessory olfactory bulb (Sanchez-Criado, 1982). In rats, the odor of males stimulates ovulation in females, an effect that is lost if the VNO is extirpated (Johns etal., 1978). Female prairie voles, M. ochrogaster, respond to odors from males with reproductive activation. Surgical removal of the VNO from adult females impedes this reproductive activation by the stud male. The weights of the uterus and the ovaries of these females were lower than those of normal or sham-operated individuals. However, the females without a VNO were still able to locate food by chemical cues (Lepri and Wysocki, 1987). 

Dry salt grass, Distichlis stricta, has high levels of phenolics after fruiting. Cinnamic acids and their vinyl phenols lower uterus weight, inhibit follicular development, and lead to cessation of reproductive activity in the montane vole Microtus montanus. Specific active compounds are 4-vinylguaiacol and 4-vinylphenol, and alsop-coumaric acid (4-hydroxycinnamic acid) (Berger etal, 1977). 

Gonadosomatic index GSl Reproduction Reproductive activity Gonad (females only) 0-13... 

There is limited evidence of both male- and female-produced sex pheromones in astigmatid mites, with female sex pheromones probably mediating a greater proportion of reproductive activities than male-produced pheromones. At present, there are indications of male sex pheromones for two Acarus spp., which also have female-produced sex pheromones (Levinson et al, 1989 Sato et al, 1993c). 

The effect of silatranes on another type of insects, the bees has been also studied. It has been found that 1-ethoxysilatrane and 1-ethoxy-3,7,10-trimethylsilatrane increase the lifespan and the weight of body and breeches of bees and stimulate the reproductive activity of the queen thus enabling the colony mass to be increased by 17—30%91. The results suggest that silatranes should be applied in bee-keeping... 

Monnin T., Malosse C., and Peeters C. (1998). Solid-phase microextraction and cuticular hydrocarbon differences related to reproductive activity in the queenless ant Dinoponera quadriceps. J. Chem. Ecol., 24,473 190. 

Apart from chemicals that act directly as pheromones in the reproductive activity of higher animals, there are many other associated materials, sometimes coming from animal excrement, that cause an arousal of interest and act as innate recognition factors between animals within a species, or as a warning to others. Some of these, as we will see later, have an important function in perfumery. 

This link between the sense of smell and reproductive activity not only goes back to the most primitive organisms but is also deeply embedded in the unconscious mind of all higher animals including humans. Research into human biology has shown that if the neural link between the nasal receptor cells and the pituitary is broken, sexual interest and function may be greatly impaired. 

Rhesus monkeys (Macaca mulatta) are another species used for DART evaluation [4], However, this species displays pronounced seasonality of reproductive activity for both sexes [13,14], In this primate, reproductive functions are entirely shut off or severely diminished for approximately half of the year. In environments with distinct seasons sexual activity and gonadal activity are present roughly throughout October until March, but this may vary substantially for individual animals. It is crucial to consider that the annual rhythmicity of reproductive cycles can persist over years in captivity and under indoor artificial light pattern conditions [15], Hence in indoor circumstances seasonality of reproduction may be uncoupled from the outdoor season, and eventually an animal may display periodic reproductive activation in unexpected months. 

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