Effects of Pup Separation on Stress Response in Postpartum Female Rats.

There is a complex collection of neuroendocrine function during the postpartum period. Prolactin (PRL) released by suckling stimulus and its PRL receptors (PRL-R) in the central nervous system (CNS) are involved in hyporesponsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in lactating mammals including rodents and humans. It is not clear how long it takes to reestablish the attenuated HPA axis activity of lactating rats to a pre-pregnancy state after pup separation.

Effects of High-Fat Diet on Stress Response in Male and Female Wildtype and Prolactin Knockout Mice.

Prolactin (PRL) is well characterized for its roles in initiation and maintenance of lactation, and it also suppresses stress-induced responses. Feeding a high-fat diet (HFD) disrupts activity of the hypothalamic-pituitary-adrenal (HPA) axis. Whether PRL regulates HPA axis activation under HFD feeding is not clear.

Revisiting influences on tumor development focusing on laboratory housing.

Spontaneous tumors are reported to occur in 45% to 71% of Sprague-Dawley rats, yet few studies have considered the effect of the sedentary condition of standard laboratory cages on tumorigenesis. Tumor profiles and tumor promoting hormone prolactin were compared in female Sprague-Dawley rats (108) that were allocated into 3 groups: those housed without outside activity (SED group), with twice-weekly 1-h sessions of physical activity in large box (PA group), and with regular voluntary running-wheel exercise (EX). Compared with the EX group, SED rats had more and larger tumors throughout most of their lifespan; tumor profiles of PA rats were similar to those of the SED group.

Effect of Nociceptin/Orphanin FQ (N/OFQ) and isoflurane on the corticosterone secretory response in mice lacking the N/OFQ prepropeptide (ppN/OFQ-/-).

The effects of subcutaneous Nociceptin/Orphanin FQ (N/OFQ) administration on corticosterone (CORT) secretion were determined in male and female wild-type mice and mice lacking the N/OFQ prepropeptide. Additionally the effect of pretreating animals with isoflurane anesthesia to minimize the potential stress of injection was examined. Although N/OFQ itself did not specifically increase CORT levels in males or females of either genotype, injection alone (either vehicle or N/OFQ) or isoflurane exposure both increased CORT levels in all groups.

Effect of orphanin FQ/nociceptin (OFQ/N) and isoflurane on the prolactin secretory response in OFQ/N knockout mice.

The prolactin secretory response to subcutaneous injection of orphanin FQ/nociceptin (OFQ/N) was measured in wild-type and OFQ/N knockout mice. These injections were given with and without isoflurane anesthesia, to determine if isoflurane would affect the prolactin secretory response. OFQ/N injection significantly increased prolactin levels in males and females, regardless of genotype, with a more robust response in females.

Estrogen regulation of neurotrophin expression in sympathetic neurons and vascular targets.

We hypothesize that estrogen exerts a modulatory effect on sympathetic neurons to reduce neural cardiovascular tone and that these effects are modulated by nerve growth factor (NGF), a neurotrophin that regulates sympathetic neuron survival and maintenance. We examined the effects of estrogen on NGF and tyrosine hydroxylase (TH) protein content in specific vascular targets. Ovariectomized, adult Sprague-Dawley rats were implanted with placebo or 17beta-estradiol (release rate, 0.

Orphanin FQ/nociceptin is a physiological regulator of prolactin secretion in female rats.

Orphanin FQ/nociceptin (OFQ/N), the most recently identified endogenous opioid peptide, stimulates prolactin secretion in both male and female rats. OFQ/N, however, did not elicit this stimulatory effect through the mu-, delta-, or kappa-opiate receptor subtype. The role OFQ/N plays in prolactin regulation under physiological conditions and its mechanism of action are not known.

Lack of involvement of dopamine and serotonin during the orphanin FQ/Nociceptin (OFQ/N)-induced prolactin secretory response.

The purpose of these studies was to examine possible mechanisms of Orphanin FQ/Nociceptin (OFQ/N)-induced prolactin release. We investigated the involvement of the dopaminergic neurons by quantifying DOPAC:DA levels in the median eminence and neurointermediate lobe following central administration of OFQ/N to female Sprague-Dawley rats. To specifically determine the involvement of the tuberoinfundibular dopaminergic neurons, immunocytochemical studies were conducted to visualize c-fos protein expression in the arcuate nucleus following central administration of OFQ/N.

Exercise improves biomarkers of health and stress in animals fed ad libitum.

Voluntary and forced exercise decrease morbidity and mortality in laboratory animals. Caloric restriction has similar effects on health and unique benefits on life span. Nonetheless, in most experiments, animals do not have access to physical activity and are fed ad libitum (AL).

Reproductive activation of pine voles (Microtus pinetorum): examination of physiological markers.

We tested the hypothesis that the presence of an opposite-sex conspecific will result in time-related changes in measures of reproductive activation. We housed male-female pairs of pine voles together for 0, 2, 6, 12, or 24 h before collecting blood, reproductive organs and brains for immunocytochemical analysis of LHRH and c-fos. Control animals were never exposed to an opposite-sex conspecific.

Acetyl-RYYRIK-NH2, a purported orphanin FQ antagonist, does not block the orphanin FQ-induced prolactin secretory response in female rats.

Acetyl-RYYRIK-NH2, a drug reported to act as an orphanin FQ/nociceptin (OFQ/N) receptor antagonist, did not block the OFQ/N-induced prolactin increase in female rats. Indeed, Acetyl-RYYRIK-NH2 pretreatment increased the magnitude and duration of the prolactin secretory response. Furthermore, by 15 min after the Acetyl-RYYRIK-NH2 pretreatment, and prior to any OFQ/N administration, circulating levels of prolactin were significantly increased in a dose-related manner, providing further evidence that this drug exhibits agonist activity.

[Phe(1)Psi(CH(2)-NH)Gly(2)]NC(1-13)NH(2) does not antagonize orphaninFQ/nociceptin-induced prolactin release.

The specificity of the orphaninFQ (OFQ)/nociceptin (N)-induced prolactin increase was determined in male and female rats by pretreating animals with different doses of [Phe(1)Psi(CH(2)-NH)Gly(2)]NC(1-13)NH(2), a compound originally reported to be a specific OFQ/N antagonist. In addition, the effect of naloxone pretreatment on OFQ/N-induced prolactin release was examined to determine if OFQ/N's effects were mediated by opiate receptors. Furthermore, dose response studies using [Phe(1)Psi(CH(2)-NH)Gly(2)]NC(1-13)NH(2) only were performed to determine potential agonist activity of this drug.