The roles of luteinizing hormone-releasing hormone (LHRH) and serotonin (5HT) in the generation of gonadotropin and prolactin (PRL) surges were investigated in microdissected brain areas of proestrous (PRO), diestrous (DIE), and photoperiod-induced anestrous (PIA) Syrian hamster…
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Adenosine plays an important role in animal physiology as the backbone of the high-energy molecule adenosine triphosphate (ATP) and also as a modulator of cellular activity through interaction with adenosine receptors. Since cellular activity causes an increase in extracellular …
Using protein chemistry, molecular biology, and electrophysiology techniques, we investigate the composition of two insect venoms with physiologically distinct actions. The first venom we explore comes from the parasitoid wasp, Ampulex compressa, which hunts the cockroach as a f…
The medial amygdala (MeA) occupies a prominent role in the neurobehavioral transformation of sensory input into sexual behavior. A central aim in neuroscience is to understand the relationship between neural structure and behavior. Thus, I studied the relationship between mating…
The suprachiasmatic nuclei (SCN) of the hypothalamus are the principal site of circadian rhythm generation. Their 24-hour rhythm is under the regulation of the daily light-dark cycle as well as under autonomous pacemaker activity. In the present study we used in vivo and in vitr…
Alzheimer's Disease (AD) is a progressive neurodegenerative disease that affects a large proportion of old people. Extensive medical evidence has closely connected AD with a dysfunction of cholinergic systems in the human brain. Ethylcholine mustard aziridinium (AF64A) is a synt…
Glutamate is the major excitatory neurotransmitter in the central nervous system. Besides its well known role as mediator of fast excitatory neurotransmission via activation of ionotropic receptors (iGluRs), glutamate also serves a modulatory role via activation of second messen…
Mammalian circadian rhythms in activity, gene expression, and pineal melatonin production are maintained by the suprachiasmatic nucleus (SCN), and are synchronized by light. One of the most abundant peptides in the brain, neuropeptide Y (NPY), has been shown to modulate circadia…
Circadian rhythms have been reported to change with age, and such changes are hypothesized to underlie changes in the timing of sleep-wake behavior and sleep disorders, problems which affect up to 40% of older people. Using an animal model, the Syrian hamster (Mesocricetus aurat…
Serotonin (5-HT) has been implicated in regulating the circadian pacemaker activity of the mammalian suprachiasmatic nuclei (SCN). However, little is known concerning the nature of 5-HT release in the SCN. The present studies examined the regulation of SCN 5-HT release using in …
The effects of activation of protein kinase C (PKC) on intermediate filaments (IFs) of different cell types were investigated. In primary cultures of murine or rabbit spinal cord, or human fibroblasts, brief exposure to activators of PKC led to the following changes in IFs: (1) …
The aim of the studies underlying this thesis was to characterize the muscarinic and adrenergic receptors expressed in rat brain oligodendrocytes' (OLs); determine if ligand binding alters second messenger levels classically associated with these families of receptors, such as i…
Reproductive activity in Syrian hamsters is determined by photoperiod. Photoperiod information is transduced by the pineal hormone melatonin through an unknown mechanism. In males maintained in long photoperiod (LP), naloxone, an opioid receptor antagonist, increased luteinizing…
Transmissible spongiform encephalopathies (TSEs) are an insidious group of neurodegenerative diseases that can replicate exponentially, exhibit strain variability, mutate, cross species barriers, and adapt to new host species. Chronic wasting disease (CWD), is an emerging TSE of…
Repeated exposure to addictive drugs produces neurochemical and structural adaptations in mesolimbic dopamine neurons. It is known that natural motivated behaviors (e.g. feeding, mating) also activate the mesolimbic dopamine pathway. Before the mechanisms underlying drug addicti…
In the Syrian hamster, the daily rhythm of activity can be reset by activity experimentally induced during the mid-day, which is the usual rest phase in nocturnal rodents. These non-photically induced phase shifts may be mediated, in whole or in part, by serotonergic input to th…
The medial amygdaloid nucleus (Me), the bed nucleus of the stria terminalis (BNST) and the medial preoptic area (MPOA) are interconnected brain regions critical to mating behavior in the male Syrian hamster. These areas relay signals from the olfactory bulbs and from gonadal ste…
In rodents, there exists a strong interaction between the reproductive and circadian systems. For this thesis the female hamster was used as a model for the study of this interaction. Studies described in chapter II investigated whether the circadian regulation of reproductive p…
Many non-equatorial species, including rodents such as hamsters, mice, and voles, are photoperiodic. In these species, changes in day length provide cues for the onset of their reproductive season. Alterations in photoperiod can result in profound morphological, physiological, a…
We are interested in studying the roles of serine/threonine kinases from Drosophila melanogaster. Drosophila has been studied as a genetic system for over a century. Thus numerous approaches are available to generate, maintain, and manipulate genetic mutants (Ashburner, 1989; Fl…