NARCOTICS RESEARCH LABORATORY

Nickolas A. Lavidis

  

  

RESEARCH

PERSONNEL in 1994 and 1995

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.
  

PROJECTS in 1994

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.
  

RESEARCH PLANNED for 1995

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.
  

COLLABORATIONS

Mechanism of neurotransmission at sympathetic varicosities of the mouse vas deferens, skeletal neuromuscular junction and the boutons of rat pelvic ganglia:
Prof. Max Bennett (1984-present).

Sensory innervation of smooth muscle cells:
Dr Dirk van Helden, Univ. of Newcastle (1994-present).

Action of opiates on intracellular calcium ion concentration:
Dr Antony Galione and Dr Thomas C. Cunnane, Univ. of Oxford (1993-present).
  

FACILITIES

The Laboratory is located within rooms 130 and 134 of the Neurobiology Laboratory.
  

OTHER RESEARCH ACTIVITES in 1994

Refereeing

Grant applications: for NHMRC (2), Australian Research Council (1).

PhD thesis examined: for Univ. of Sydney (1).

Conference organization

Australian Neuroscience Colloquium, Univ. of Newcastle (Oct).

NSW & ACT Fellows meetings

Attended every meeting held in 1994.

Invited conference talk

Australian Neuroscience Society, Sydney (Feb).

Seminar

To Dept of Anatomy, Univ. of N.S.W. (May).
  

THESES PASSED in 1994

PhD

Karunanithi S (1994) The role of ATP in somatic and sympathetic neuromuscular transmission.

BMedSc(Hons)

Theodorou M (1994) The role of nitric oxide on synaptic transmission in the guinea-pig vas deferens (Result: 2nd Class, Div. 1)
  

5-YEAR RESEARCH PUBLICATIONS

MOST RECENT TOTAL ANNUAL CITATIONS (for 1993): 31

  

FUNDING in 1994 and 1995

NHMRC The effects of opiates on the probability
of quantal secretion at sympathetic
varicosities
Lavidis NA 1992
1993
1994 $66,345
1995 $66,345

NHMRC Mechanism of transmitter secretion at
sympathetic nerve varicosities
Bennett MR 1994 $67,673
Lavidis NA 1995 $67,673
1996

NHMRC Probability of quantal secretion at
neuromuscular synapses
Bennett MR 1994 $51,059
Lavidis NA 1995 $51,059
1996

NHMRC Effect of chronic morphine treatment on
sympathetic varicosities innervating
the mouse vas deferens
Lavidis NA 1995 $15,974
1996
1997

Ramaciotti
Foundation
The development of tolerance to opiates
by sympathetic nerve endings
Lavidis NA 1995 $20,000

Total for 1994: $185,077

Total for 1995: $221,651