Intracranial cannula along with electrodes was stereotaxically implanted in medial preoptic area of male rats. The electrical activity of mPOA was recorded before and after microinjection of GABA (0.5 micrograms/02 microliters), muscimol (0.5 micrograms/0.2 microliter), picrotoxin (0.25 micrograms/0.2 microliter) and their respective controls. Generalized slowing with an increase in amplitude a...

Neurogenesis was studied in the medial preoptic area of the guinea pig by the method of tritiated thymidine autoradiography. Eight cytoarchitectonic divisions were examined, 4 of which display sexual dimorphism and 4 that do not. Neurogenesis in the nonsexually dimorphic divisions was found to end at embryonic day (E) 27, while in each of the sexually dimorphic divisions neurogenesis continued ...

We tested the hypotheses that progesterone enhances the negative feedback actions of testosterone in rams and that this occurs through actions at the hypothalamus. In the first part of this study, blood samples were collected every 10 min for 12 h before and after 7 days of treatment (i.m.) of castrated Romney Marsh rams (n=5 per group) with vehicle, progesterone (4 mg/12 h), testosterone (4 mg...

ABRAMS, ROBERT, AND H. T. HAMMEL. Cyclic variations in hypothalamic temperature in unanesthetised rats. Am. J. Physiol. 208(4): 698-702. 1965. -Male and female rats, equipped with stainless steel re-entrant tubes implanted in the brain adjacent to one preoptic area, were placed in cages with accessible activity wheels. Brain temperatures were recorded continuously for periods up to 48 hr by mea...

The preoptic area (POA) plays an important role in fever in mammals, but the role of this region in fever in ectothermic vertebrates has never been assessed. Toads, like all ectotherms, regulate their body temperature (T(b)) primarily by behavior and develop behavioral fever when injected with lipopolysaccharide (LPS). Therefore, we tested the hypothesis that the POA plays a role in the behavio...

Tunicates (sea squirt) are filter feeders which process liters of sea water daily. They have a preemptive organelle similar to the vertebrate thyroid called an endostyle. The endostyle has been identified as site for iodine metabolism. Our hypothesis was that microbial symbionts associated with endostyle play a role in iodine metabolism. Using Ascidiella aspersa (sea squirt) as the model, we ha...

..........................................................................................1 CHAPTER I: INTRODUCTION....................................................................3 CHAPTER II: Steroidal Regulation of synaptic density in the magnocellular division of the medial preoptic nucleus (MPN mag) of the Syrian Hamster..............................19 Introduction.........................

Two distinct subgroups of gonadotropin-releasing hormone (GnRH) neurons are involved in the control of luteinizing hormone secretion, at least in rats: one subgroup located in the mediobasal hypothalamus constitutes the GnRH pulse generator associated with opioid neurons, and the other located in the preoptic area constitutes the GnRH surge generator associated with gamma-aminobutyric acid neur...

Reward mechanisms are involved in pair bond formation in monogamous prairie voles. Given the potential role of CART (cocaine- and amphetamine-regulated transcript) in reward, and its possible role as a third neurohypophysial hormone, we examined the brain distribution of CART mRNA and peptide in monogamous prairie voles compared to congener promiscuous meadow voles. Large species differences in...

BACKGROUND Despite seventeen decades of continuous clinical use, the neuronal mechanisms through which volatile anesthetics act to produce unconsciousness remain obscure. One emerging possibility is that anesthetics exert their hypnotic effects by hijacking endogenous arousal circuits. A key sleep-promoting component of this circuitry is the ventrolateral preoptic nucleus (VLPO), a hypothalamic...