Effects of β-estradiol on cold-sensitive receptor channel TRPM8 in ovariectomized rats

Transient receptor potential cation channel subfamily M member 8 (TRPM8) is associated with sensitivity to cold sensation in mammals. A previous study demonstrated that TRPM8 was overexpressed in the skin of ovariectomized (OVX) rats due to the loss of estrogen. In the present study, we investigated whether estrogen replacement restricts overexpression of the TRPM8 channel in the skin of OVX rats. We divided 15 Sprague Dawley rats into three groups: a non-operated group (NON-OPE), an ovariectomy group (OVX), and a group subjected to estrogen replacement during 4 weeks beginning 7 days after ovariectomy (OVX + E2). Five weeks later, TRPM8 channel mRNA and protein in lumbar skin were quantified by real-time RT-PCR, protein ELISA, and immunohistochemistry. The OVX + E2 group exhibited a trend for decreased expression of the TRPM8 channel in the lumbar skin in comparison with the OVX group, whereas ELISA data and immunohistochemistry data and immunohistochemistry graphs relating to TRPM8 protein did not show any obvious differences between the OVX group and the OVX + E2 group. Estrogen replacement may restrict the overexpression of TRPM8 in the dermis of OVX rats.

Cohort profile: Women's Healthy Ageing Project (WHAP) - a longitudinal prospective study of Australian women since 1990

Background

The cohort was commenced to examine women’s health from midlife (45–55 years) before the menopausal transition and into ageing.

Methods

Randomised selection and assessment of 2,001 women living in the Melbourne metropolitan area was conducted by the Roy Morgan Centre in 1990/91. Of the 779 women who met the entry criteria for the longitudinal follow-up (aged 45–55 years, menstruating, having a uterus and at least one ovary and not taking hormone therapy) 438 agreed to be seen annually across the menopausal transition from 1992 to 1999. Longitudinal prospective follow-up since 2000 has continued intermittently (2002/03, 2004/05, 2012/13, 2014/15). Data collection has included fasting biomarkers in each year since 1992, clinical assessment, lifestyle and quality of life data, physical measures and validated questionnaire data. Participants have consented to data linkage and, to date, mammogram and BioGrid data have been accessed. Biobank storage including serum, deoxyribonucleic acid (DNA) storage and PAXgene tubes are maintained.

Discussion

The WHAP has contributed to over 200 published research findings, several books, and book chapters in a variety of areas, including: health and wellbeing; mental and cognitive health; bone health; lifestyle, vascular risk and prevention; women’s health and hormonal transition; and cross-cultural research.

With all participants now aged over 70 years, the cohort is ideally placed to answer key questions of healthy ageing in women. With more than 25 years of longitudinal prospective follow-up this Australian dataset is unique in its duration, breadth and detail of measures including clinical review and specialized disease-specific testing and biomarkers. Ongoing follow-up into older ages for this long-running cohort will enable the association between mid to late-life factors and healthy ageing to be determined. This is particularly valuable for the examination of chronic diseases which have a 20–30 year prodrome and to provide knowledge on multiple morbidities. The dataset has a unique opportunity to improve our understanding of temporal relationships and the interactions between risk factors and comorbidities.

Electronic supplementary material

The online version of this article (doi:10.1186/s40695-016-0018-y) contains supplementary material, which is available to authorized users.

Immunohistochemical evidence for the involvement of gonadotropin releasing hormone in neuroleptic and cataleptic effects of haloperidol in mice

Blockade of dopamine D2 receptor by haloperidol is attributed for neuroleptic and cataleptic effects; and also for the release of gonadotropin releasing hormone (GnRH) from the hypothalamus. GnRH agonist is reported to exhibit similar behavioural effects as that of haloperidol, and pre-treatment with GnRH antagonist is shown to attenuate the effects of haloperidol, suggesting a possibility that GnRH might mediate the effects of haloperidol. To substantiate such possibility, the influence of haloperidol on GnRH immunoreactivity (GnRH-ir) in the brain was studied in vehicle/antide pre-treated mice by peroxidase-antiperoxidase method. Initially, an earlier reported antide-haloperidol interaction in rat was confirmed in mice, wherein haloperidol (250μg/kg, i.p.) exhibited suppression of conditioned avoidance response (CAR) on two-way shuttle box, and induced catalepsy in bar test; and pre-treatment with antide (50μg/kg, s.c., GnRH antagonist) attenuated both effects of haloperidol. Immunohistochemical study was carried out to identify GnRH-ir in the brain, isolated 1h after haloperidol treatment to mice pre-treated with vehicle/antide. The morphometric analysis of microphotographs of brain sections revealed that haloperidol treatment increased integrated density units of GnRH-ir in various regions of the limbic system. Considering basal GnRH-ir in vehicle treated group as 100%, the increase in GnRH-ir after haloperidol treatment was by 100.98% in the medial septum; 54.26% in the bed nucleus of the stria terminalis; 1152.85% in the anteroventral periventricular nucleus; 120.79% in the preoptic area-organum vasculosum of the lamina terminalis and 138.82% in the arcuate nucleus. Antide did not influence basal and haloperidol induced increase in GnRH-ir in any of the regions. As significant increase in GnRH-ir after haloperidol treatment was observed in such regions of the brain which are reported to directly or indirectly communicate with the hippocampus and basal ganglia, the regions respectively responsible for neuroleptic and cataleptic effects; and as GnRH antagonist eliminated the effects of haloperidol without affecting GnRH-ir, it appears that GnRH released by haloperidol mediates its neuroleptic and cataleptic effects.

A possible participation of gonadotropin-releasing hormone in the neuroleptic and cataleptic effect of haloperidol

Haloperidol, an antipsychotic agent, stimulates the release of gonadotropin-releasing hormone (GnRH), and this hormone is known to mimic some of the behavioral effects of haloperidol. Hence, the present study was carried out to find out the contribution of GnRH in the behavioral effects of haloperidol. The studies revealed that haloperidol (0.15, 0.25 and 0.5 mg/kg, i.p.) and leuprolide (GnRH agonist; 50, 100, 200 and 400 microg/kg, s.c.) dose-dependently inhibited conditioned avoidance response (CAR) in male Sprague-Dawley rats. In higher doses, haloperidol (0.5, 1 mg/kg, i.p.) and leuprolide (200, 400 microg/kg, s.c.) produced catalepsy in rats. Co-administration of sub-effective dose of leuprolide (50 or 100 microg/kg, s.c.) and haloperidol (0.15 or 0.5 mg/kg, i.p.) similarly inhibited CAR and induced catalepsy. Pre-treatment of rats with antide (GnRH antagonist; 10 microg/rat, s.c.), attenuated the inhibitory effect of both the agents on CAR; blocked leuprolide-induced catalepsy; and attenuated the intensity and reduced the duration of haloperidol-induced catalepsy. In conclusion, the studies suggest a possible role of GnRH in the neuroleptic and cataleptic effect of haloperidol.