Stereology of gonadotropin-releasing hormone and kisspeptin neurons in PACAP gene-deficient female mice.

The hypothalamic gonadotropin-releasing hormone (GnRH)-kisspeptin neuronal network regulates fertility in all mammals. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide isolated from the hypothalamus that is involved in the regulation of several releasing hormones and trop hormones. It is well-known that PACAP influences fertility at central and peripheral levels. However, the effects of PACAP on GnRH and kisspeptin neurons are not well understood. The present study investigated the integrity of the estrous cycle in PACAP-knockout (KO) mice. The number and immunoreactivity of GnRH (GnRH-ir) neurons in wild-type (WT) and PACAP KO female mice were determined using immunohistochemistry. In addition, the number of kisspeptin neurons was measured by counting kisspeptin mRNA-positive cells in the rostral periventricular region of the third ventricle (RP3V) and arcuate nucleus (ARC) using the RNAscope technique. Finally, the mRNA and protein expression of estrogen receptor alpha (ERα) was also examined. Our data showed that the number of complete cycles decreased, and the length of each cycle was longer in PACAP KO mice. Furthermore, the PACAP KO mice experienced longer periods of diestrus and spent significantly less time in estrus. There was no difference in GnRH-ir or number of GnRH neurons. In contrast, the number of kisspeptin neurons was decreased in the ARC, but not in the R3PV, in PACAP KO mice compared to WT littermates. Furthermore, ERα mRNA and protein expression was decreased in the ARC, whereas in the R3PV region, ERα mRNA levels were elevated. Our results demonstrate that embryonic deletion of PACAP significantly changes the structure and presumably the function of the GnRH-kisspeptin neuronal network, influencing fertility.

17ß-estradiol does not have a direct effect on the function of striatal cholinergic interneurons in adult mice in vitro.

The striatum is an essential component of the basal ganglia that is involved in motor control, action selection and motor learning. The pathophysiological changes of the striatum are present in several neurological and psychiatric disorder including Parkinson's and Huntington's diseases. The striatal cholinergic neurons are the main regulators of striatal microcircuitry. It has been demonstrated that estrogen exerts various effects on neuronal functions in dopaminergic and medium spiny neurons (MSN), however little is known about how the activity of cholinergic interneurons are influenced by estrogens. In this study we examined the acute effect of 17ß-estradiol on the function of striatal cholinergic neurons in adult mice in vitro. We also tested the effect of estrus cycle and sex on the spontaneous activity of cholinergic interneurons in the striatum. Our RNAscope experiments showed that ERα, ERß, and GPER1 receptor mRNAs are expressed in some striatal cholinergic neurons at a very low level. In cell-attached patch clamp experiments, we found that a high dose of 17ß-estradiol (100 nM) affected the spontaneous firing rate of these neurons only in old males. Our findings did not demonstrate any acute effect of a low concentration of 17ß-estradiol (100 pM) or show any association of estrus cycle or sex with the activity of striatal cholinergic neurons. Although estrogen did not induce changes in the intrinsic properties of neurons, indirect effects via modulation of the synaptic inputs of striatal cholinergic interneurons cannot be excluded.

Long-term effects of adding exenatide to a regimen of metformin and/or sulfonylurea in type 2 diabetes: an uncontrolled, open-label trial in Hungary.

BACKGROUND: Studies of the glucagon-like peptide-1 receptor agonists (GLP-1RAs) are needed to determine the durability of metabolic response and tolerability associated with long-term treatment. OBJECTIVE: The present study was conducted to provide long-term data on glycemic control, weight changes, and tolerability of exenatide 10 µg BID treatment in patients with type 2 diabetes mellitus who have failed to achieve glycemic targets with oral antihyperglycemic medication. METHODS: In this uncontrolled, open-label trial with treatment up to 156 weeks, patients received exenatide 10 µg BID while continuing treatment with metformin and/or a sulfonylurea (SFU). Intent-to-treat (ITT), 52-, 100-, and 132-week completer populations were defined. Metabolic changes were analyzed in the completer and ITT populations; adverse events (AEs) were summarized in the ITT population. Descriptive statistics were used for absolute and change-from-baseline data. Within-treatment comparisons were conducted using the paired t test. RESULTS: Of 155 patients in the ITT population (mean [SD]: age, 59 [9] years; 56% female; duration of diabetes, 9.1 [5.9] years; weight, 88.8 [16.5] kg; body mass index, 31.9 [4.7] kg/m(2); hemoglobin [Hb] A(1c), 8.7% [1.2%]), 133, 111, and 103 patients completed 52, 100, and 132 weeks of treatment, respectively. In the ITT population, the mean (SE) change in HbA(1c) from baseline to week 132 was -1.0% (0.10%) (P < 0.0001). In patients completing 52, 100, and 132 weeks, HbA(1c) changes from baseline to end point were -1.3% (0.10%), -1.0% (0.12%), and -1.0 (0.13%) (P < 0.0001), with 40% of patients achieving HbA(1c) <7% at 132 weeks. Patients in the ITT and completer populations experienced mean (SE) weight changes of -3.7 (0.39) kg and -3.9 (0.51) kg (P < 0.0001) at week 132. Improved glycemic control and weight loss occurred in 63% of patients in the completer population at week 132. In addition, 38% of completers at week 132 achieved HbA(1c) <7% without weight gain. No relationship was found between the development of antiexenatide antibodies and change in HbA(1c). The most common AEs were gastrointestinal in nature, reported in 46% of patients and leading to discontinuation in 7 cases. Serious AEs were reported in 26% of patients, and 18% withdrew due to a treatment-emergent AE. Of 24% of patients in whom hypoglycemia was reported, 22% were on SFU or metformin + SFU combination, and 2% were on metformin. CONCLUSIONS: The findings from this open-label, single-arm study characterized the response to exenatide 10 µg BID for up to 132 weeks. Significant, persistent improvements in HbA(1c) and weight were observed in patients receiving exenatide BID, with reported AEs consistent with those from studies of shorter duration. ClinicalTrials.gov identifier: NCT00044668.

The effect of exenatide re-exposure on safety and efficacy.

Exenatide, a synthetic peptide originally isolated from salivary secretions of Heloderma suspectum, like other subcutaneously injected peptides, can cause antibody formation. Despite that antibody formation has been observed in some patients, results from previous clinical trials have not shown safety and efficacy concerns in exenatide-naïve patients. The objective of this multicenter, open-label study was to investigate the response of anti-exenatide antibody formation and the incidence of immune-related and hypersensitivity reactions after exenatide re-exposure. Fifty-eight patients (57% male; 59+/-10 years; weight 85+/-19kg; HbA1c 8.1+/-0.9%; duration of diabetes 10+/-5 years) were enrolled. At study initiation, 98.3% of patients were taking 1 or more antidiabetes drugs, including oral medication and various types of insulin. Treatment-emergent adverse events (TEAEs) at any time during the study were observed in 40 and 47% of patients with positive and negative treatment-emergent antibodies, respectively. Immune-related AEs were observed in 6 patients (4 were antibody positive). These AEs had not been reported in their previous exposure to exenatide. Re-exposure to exenatide did not result in increased hypersensitivity reactions. Overall, 72% of patients had a baseline to endpoint reduction in HbA1c (range -0.1 to -2.8%), and 87% of antibody negative versus 62% of antibody positive patients had an HbA1c endpoint reduction. The study design and the patients' baseline characteristics, including diabetes treatment at study initiation, are confounding factors limiting clinical conclusions on exenatide's glycemic effect in this patient population. The study results indicate that anti-exenatide antibody formation did not increase the incidence of TEAEs in patients re-exposed to exenatide.