Interactive effects of intracisternal oxytocin and other centrally active substances on colonic temperatures of mice

Oxytocin (OXY) administered intracisternally to adult male mice produced a significant dose-related (1-4 micrograms) increase in colonic temperatures at an ambient temperature of 25 degrees C. The maximal rise in temperature occurred 30 min after administration of the peptide. The interactive effects on colonic temperature of central OXY with equimolar amounts of neurotensin, bombesin or beta-endorphin or of 2 2 mg/kg of chlorpromazine were investigated. OXY significantly antagonized the hypothermia produced by all of these substances. Pretreatment of mice with haloperidol or naloxone failed to prevent OXY-induced hyperthermia. The hyperthermic action of OXY and the interactive effects of OXY with other peptides on thermoregulation may be physiologically significant during parturition and lactation.     

A comparison of grooming behavior potencies of neurohypophyseal nonapeptides

We have previously demonstrated that intracerebroventricular (ICV) administration of oxytocin (OXY) enhanced grooming behaviors in male and female rats at a 1 microgram dose. In the present study female rats were injected ICV with 1 microgram OXY or equimolar doses of other peptides. At this dose arginine-vasopressin (AVP), arginine-vasotocin (AVT) and lysine-vasopressin (LVP), as well as alpha-MSH, were as effective as OXY in increasing grooming behavior. At equimolar doses, ACTH1-10, tocinoic acid (the ring structure of OXY) and Pro-Leu-Gly-NH2 (the tail structure of OXY) had no significant effect on grooming behavior. The potency of AVP and AVT was determined across a 0.05-5 microgram dose range. Grooming scores increased in an apparent linear manner across a similar OXY dose range. Both AVP and AVT, however, manifested an inverted U grooming response curve. Maximum grooming scores resulted from a 0.1 microgram dose of AVT or a 0.5 microgram AVP dose. Analyses of the aspects of grooming separately found that nonapeptides OXY, AVP and AVT all elevated body grooming, washing, and scratching. Because AVT and AVP administration resulted in grooming scores significantly higher than OXY at lower doses, we concluded that the CNS is more sensitive to the effects of AVT and AVP on grooming behavior than OXY.     

Use of an immediate, qualitative progesterone assay for determination of day of ovulation in an equine embryo transfer program

An immediate, qualitative enzyme-linked immunosorbent assay (ELISA) for progesterone was evaluated for use in determining the day of ovulation in an equine embryo transfer program. Plasma samples were collected from 27 mares from the third day of estrus to the second day of diestrus for 50 cycles. Ovulation was detected by ultrasound examination per rectum. Plasma progesterone concentrations were estimated using the qualitative assay to detect the time of the rise in progesterone after ovulation. Qualitative scores were compared to progesterone concentrations for the same samples as measured by a quantitative ELISA; the correlation between the two methods, expressed as a contingency coefficient, was 0.56. The accuracy of determining day of ovulation using qualitative progesterone results was compared to that achieved using the quantitative assay or detection of the first day of diestrus by teasing. Accuracy in determining day of ovulation +/- 1 d using the three methods was qualitative, 36/50 (72%); quantitative, 44/50 (88%); and teasing, 43/50 (86%). There was a significant difference in accuracy between the qualitative and quantitative progesterone assays (P<0.05).     

Caenorhabditis elegans as a model system for identifying effectors of α-synuclein misfolding and dopaminergic cell death associated with Parkinson's disease

Protein misfolding and aggregation are key pathological features observed in numerous neurodegenerative diseases, including the misfolding of α-synuclein (α-syn) in Parkinson's disease (PD) and β-amyloid in Alzheimer's disease. While this phenomenon is widely observed, the etiology and progression of these diseases is not fully understood. Furthermore, there is a lack of therapeutic treatments directed at halting the progression and neurodegeneration associated with these diseases. This demands a need for an inexpensive, easy to manipulate multicellular organism to conduct both genetic and chemical screens within to identify factors that may play a pivotal role in the pathology of these diseases. Herein, we describe methodology involved in identifying genetic modifiers of α-syn misfolding and toxicity in the nematode roundworm, Caenorhabditis elegans. Transgenic nematodes engineered to express human α-syn in the body wall muscles or dopaminergic (DA) neurons result in formation of cytoplasmic puncta or DA neurodegeneration, respectively. Using these models, we describe the use of RNA interference (RNAi) and transgenic gene expression to functionally elucidate potential therapeutic gene targets that alter α-syn misfolding and DA neurotoxicity.     

INFLUENCE OF FLORAL OPTICAL PROPERTIES ON THE ULTRAVIOLET RADIATION ENVIRONMENT OF POLLEN

Pollen in unopened flowers of most species is totally screened from solar ultraviolet-B radiation by imbricated petals that are largely opaque to UV-B. Following flower opening but before anther dehiscence, the anther walls of the species investigated filter out over 98% of the UV-B radiation. Reflectance of UV from corollas of open flowers does not generally appear to add significantly to the solar UV-B radiation environment of pollen.