Background/Aims: We established a cynomolgus macaque model of stress-induced amenorrhea in which the application of combined metabolic and psychosocial stress suppressed ovulation in stress-sensitive (SS) individuals, but not in highly stress-resilient (HSR) individuals. We previously reported that SS monkeys have deficits in global serotonin release and serotonin-related gene expression in the raphe nucleus, and that administration of the selective serotonin reuptake inhibitor S-citalopram increased estrogen and progesterone production in SS monkeys. In this study, we questioned whether there was a difference in corticotropin-releasing factor (CRF) or urocortin (UCN) stress-related peptide systems in the midbrain raphe region when HSR and SS monkeys treated with placebo or S-citalopram are compared. Methods: Monkeys characterized as HSR or SS were administered placebo or S-citalopram for 15 weeks. CRF fibers in the dorsal raphe were detected with an antibody against human CRF. UCN1 fibers were immunostained in an area rostral to the dorsal raphe. The fibers were quantified by stereology and analyzed by two-way ANOVA. UCN1 cell bodies were counted in the supraoculomotor area near the Edinger-Westphal nucleus. Results: S-citalopram significantly decreased the CRF fiber density in SS animals, but not in HSR animals. SS monkeys had a significantly lower UCN1 fiber density compared to HSR monkeys, but S-citalopram treatment did not alter the UCN1 fiber density. SS animals treated with S-citalopram tended to have a higher number of UCN1-positive cell bodies than the other groups. Conclusion: S-citalopram decreased CRF fiber density and appears to increase the production of UCN1 in SS individuals, indicating the likelihood that serotonin is involved in regulating CRF and UCN1 in individuals who are sensitive to the effects of serotonin.
This chapter reviews the neurobiological effects of stress sensitivity and CIT treatment observed in our nonhuman primate model of Functional Hypothalamic Amenorrhea (FHA). This type of infertility, also known as stress-induced amenorrhea, is exhibited by cynomolgus macaques. In small populations, some individuals are stress sensitive (SS) and others are highly stress resilient (HSR). The SS macaques have suboptimal secretion of estrogen and progesterone during normal menstrual cycles. SS monkeys also have decreased serotonin gene expression and increased CRF expression compared to HSR monkeys. Recently, we found that s-citalopram (CIT) treatment improved ovarian steroid secretion in SS monkeys, but had no effect in HSR monkeys. Examination of the serotonin system revealed that SS monkeys had significantly lower Fev (fifth Ewing variant, rodent Pet1), TPH2 (tryptophan hydroxylase 2), 5HT1A autoreceptor and SERT (serotonin reuptake transporter) expression in the dorsal raphe than SR monkeys. However, CIT did not alter the expression of either Fev, TPH2, SERT or 5HT1A mRNAs. In contrast, SS monkeys tended to a higher density of CRF fiber innervation of the dorsal raphe than HSR monkeys, and CIT significantly decreased the CRF fiber density in SS animals. In addition, CIT increased CRF-R2 gene expression in the dorsal raphe. We speculate that in a 15-week time frame, the therapeutic effect of S-citalopram may be achieved through a mechanism involving extracellular serotonin inhibition of CRF and stimulation of CRF-R2, rather than alteration of serotonin-related gene expression.
The investigation of antibodies raised against SARS-CoV-2 can help to determine the extent of previous SARS-CoV-2 infections and track the humoral response to vaccination. Here we describe a time series anti-nucleocapsid, anti-spike IgG serological survey in the city of Matinhos, PR, Brazil during the year of 2021.
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