Disease relevance of Anestrus

• These results suggest that hyperprolactinemia mediated through hypothalamic dopamine depletion is the mechanism of anestrus in rats treated with losulazine [1].
• Ovarian scans and blood collected before injections for progesterone analysis were used to classify 4 ovarian status groups: anestrus, follicular cysts, luteal cysts, and cycling, plus an unknown group of females in which no blood sampling or ovarian scans were made [2].
• Studies were conducted in Korean native cattle to determine the age and body weight at puberty, and to determine the postpartum anestrus intervals based on plasma progesterone profiles, rectal palpation, ultrasonography and estrus observation [3].

High impact information on Anestrus

• Cellular GH production in nontumorous tissues was more extensive during the progesterone-dominated luteal phase of the ovarian cycle or during exposure to synthetic progestins than during anestrus [4].
• The highest levels of CRBP I were seen during anestrus and proestrus, and for CRABP I during proestrus [5].
• Thyroid hormone action on the development of neuroendocrine anestrus is known to be limited to a specific seasonal window [6].
• This long-day suppression of Dio2 may provide a mechanism that accounts for the lack of responsiveness to thyroxine during the mid to late anestrus [6].
• Hourly GnRH pulses were delivered to ovariectomized ewes in which endogenous GnRH pulses were blocked by estradiol during seasonal anestrus [7].

Biological context of Anestrus

• Progesterone metabolism was examined in tissues of rats in three stages of reproductive senescence (constant estrus, repeated pseudopregnancies, and anestrus) and in young rats [8].
• Concurrent pulsatile secretion of luteinizing hormone and follicle-stimulating hormone during different phases of the estrous cycle and anestrus in beagle bitches [9].
• Therefore, treating bucks with long days and melatonin increased their teasing capacity to induce sexual activity in females during anestrus [10].
• Enhancement of aromatase gene expression in the mediobasal hypothalamus during anestrus in the beagle bitch [11].
• Effect of stage of anestrus on the induction of estrus by the dopamine agonist cabergoline in dogs [12].

Anatomical context of Anestrus

• As expected, LH remained elevated through the end of the study (April) in THX controls not receiving thyroxine, confirming that the neuroendocrine transition to anestrus is dependent on thyroid hormones [13].
• Two photoperiod-controlled neuroendocrine systems appear to suppress secretion of tonic luteinizing hormone (LH) in anestrous ewes: a steroid-independent system that decreases LH pulse frequency in ovariectomized ewes and a steroid-dependent system whereby estradiol gains the capacity to suppress LH pulse frequency in anestrus [14].
• Increasing gonadotropin-releasing hormone release by perifused hypothalamus from early to late anestrus in the beagle bitch [15].
• The hypothesis studied was that genistein, infused for several hours into the third ventricle, could immediately affect LH and PRL secretion in ovariectomized (OVX) ewes during seasonal anestrus [16].
• The number of cells in the arcuate nucleus/median eminence region (ARC-ME) that stained for NPY was lower in ewes killed in anestrus (September) than in ewes killed in the breeding season (May), but there was no seasonal change in the number of galanin-stained cells [17].

Associations of Anestrus with chemical compounds

• Pulsatile release of luteinizing hormone and the secretion of ovarian steroids in sheep during anestrus [18].
• In pinealectomized ewes, the night-time rise of melatonin was absent, and transfer from long to short days failed to reverse the capacity of estradiol to inhibit LH secretion during anestrus [19].
• One stage of this rhythm, the transition to anestrus, requires the presence of thyroid hormone during a window of responsiveness that opens in the late breeding season [20].
• Pimozide also increased pulsatile LH secretion in ovariectomized ewes treated with estradiol in anestrus to suppress LH pulse frequency, but phenoxybenzamine was ineffective in these animals [21].
• The peripheral concentration of LH and the secretion rates of estradiol-17beta and androstenedione were measured every 10 min for 4 h during anestrus in six ewes with utero-ovarian autotransplants [18].

Gene context of Anestrus

• To study the effect of starvation on hypothalamic beta-endorphin and somatostatin (SRIF) concentrations in relation to starvation induced anestrus, groups of 8 rats were fed 50% of their normal daily chow consumption [22].
• Increased concentrations of circulating prolactin (Prl) seen in these animals are not responsible for the reversal of photoperiodic anestrus as demonstrated by experimental manipulations of prolactin secretion [23].
• We therefore examined GnRH neurons of breeding season (BS) and nonbreeding season (anestrus) ewes and tested the hypotheses that specific (i.e. gamma-aminobutyric acid, catecholamine, neuropeptide Y, or beta-endorphin) inputs to GnRH neurons change seasonally, and concomitant with any changes in neural inputs is a change in glial apposition [24].
• E2 treatment produced a 3-fold increase in the percentage of ERalpha-positive cells expressing Fos (15.1% vs. 3.4%) in anestrus, but failed to increase ERalpha/Fos colocalization (1.8% vs. 3.5%) during the breeding season [25].
• Changes in serum levels of PRL have been implicated in the development of seasonal reproductive quiescence in male hamsters, yet the role of serum PRL in seasonal anestrus in the female has not been examined [26].

Analytical, diagnostic and therapeutic context of Anestrus

• Estradiol (E2), testosterone (T) and progesterone (P4) concentrations were determined by enzyme-immunoassay in aqueous extracts of fecal samples obtained during anestrus, proestrus, estrus and metestrus of 11 nonpregnant and 11 pregnant bitches [27].
• The anestrous syndrome was specifically studied and was defined as no estrus occurrence by postpartum day 60 (postpartum anestrus) or by 21 to 24 days after insemination, if a negative early pregnancy test based on milk progesterone concentrations was obtained (postinsemination anestrus) [28].

References