|Dr Nickolas A. Lavidis||R.D. Wright Fellow (in-charge)||NHMRC||1978-|
|David Kyungwan Kim||BMedSc(Hons) student||1995|
|(Those with Max Bennett: Supervisor; Nickolas Lavidis: Associate Supervisor in '94)|
|Dr Shanker Karunanithi||Research Officer||NHMRC||1989-|
|Darren Warren||PhD student||1992-|
|Maria Theodorou||BSc(Hons) student||1994|
|Svetlana Cherepanoff||GradDipSc student (0.5)||1993-94|
|Yon-Qi Lin||Research Officer (PhD 0.8 from '95)||ARC||1990-|
|Gregory T. MacLeod||Research Assistant (PhD + RA 0.6 from '95)||NHMRC||1991-|
Current effective full-time personnel (with all co-supervised taken as 0.5) = 3.7
The Narcotics Research Laboratory is located within the Neurobiology Laboratory and is concerned with identifying the changes in the mechanism of transmitter secretion which manifest during the development of tolerance and acute withdrawal in animals which have been chronically inhibited from secreting neurotransmitter.
Effect of opiates on transmitter secretion from the boutons of rat pelvic ganglia
DiOC2(5)-fluorescence was used to visualize boutons before placing electrodes (6 µm) extracellularly over 1 to 4 boutons to record the nerve impulses, synaptic currents and the postsynaptic action potential while stimulating the hypogastric nerve at 0.1 Hz. The effects of morphine (10 µM), dynorphin-A (0.1 µM) and trans-(+)-3,4-dichloro-N-methyl-N-(2-[1-pyrrolidinyl]cyclohexyl) (U50488) on the nerve terminal impulse and transmitter secretion were evaluated. It was demonstrated that dynorphin-A and U50488 (k-opioid receptor agonists) decrease transmitter secretion from boutons of rat pelvic ganglia without affecting the nerve impulse propagating along the axons of the hypogastric nerve and that increasing extracellular Ca2+ concentration or the addition of naloxone reduced the effects of dynorphin-A and U50488.
Interaction between opioid receptors and a2-adrenoceptors on sympathetic varicosities of chronically morphine treated mouse vasa deferentia
Since the effects of a2-adrenoceptor and k-opioid receptor agonists are very similar, this prompted an investigation of the interaction between a2-adrenoceptors and opioid receptors in affecting transmitter secretion in CMT preparations. This study has demonstrated that although CMT induces an increase in the probability of transmitter secretion and indirectly reduces the effect of clonidine. There was no evidence of any interaction between a2-adrenoceptors and opioid receptors since idazoxane antagonized the effects of clonidine but not the effects of morphine. The effects of idazoxane on naive and CMT preparations during stimulation by trains of impulses were consistent with the hypothesis that CMT induces an increase in the probability of transmitter without altering the affects of secreted noradrenaline on a2-adrenoceptors.
The physical change responsible for the increase in probability of quantal secretion from sympathetic varicosities of animals which had been chronically morphine treated will be investigated.
The Laboratory is located within rooms 130 and 134 of the Neurobiology Laboratory.
MOST RECENT TOTAL ANNUAL CITATIONS (for 1993): 31
|NHMRC||The effects of opiates on the probability
of quantal secretion at sympathetic
|NHMRC||Mechanism of transmitter secretion at
sympathetic nerve varicosities
|NHMRC||Probability of quantal secretion at
|NHMRC||Effect of chronic morphine treatment on
sympathetic varicosities innervating
the mouse vas deferens
|The development of tolerance to opiates
by sympathetic nerve endings
Total for 1994: $185,077
Total for 1995: $221,651