1955_evarts_4016_1.pdf

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_W-f2 " NOoI3 _ (§i02a)
•_ b_Xotenine
(§ 90b)
M 500 effects on visual system
EVARTS, EoVo, LANDAU_ Woo FREYGANG, Wo 9 MARSHALL, WoHo
(Natolnsto
of MentoHealth_ NatoInsts of Health, Bethesda, Maryland)
_@ffects
cal activity
_"
_H
of _id
die_thylamideand bufotenin e on electri-
in the cat's visual system°
Amero Physiol18___2,594()o
Jo
o
1955
[l_liEM:
LSD produces gross alterations of visual reactions in
c@A_cious monkeys_ lo0 mg/kg causing a decreased or absent response
t_isual
stimuli without gross effect on muscular power (EVARTS_
_ublished)
o A study was therefore made in cats to determine the
e_e_trophysiological
effects of LSD within the visual system° Similar
studi s were made of bufotenine (a dimethyl derivative of serotoni_h
_u
_e in conscious monkeys this drug has effects similar to tho_
of Lso.
,_ ed
IA_RIAL
and DOSAGE" Cats (2.5-4.8 kg) were anaesthetized with iopo
(35 mg/kg)o LSD and bufotenine
were administered
lateral
via
geni-
._0barbitone
the_carotid artery. Electrical activity in the retina,
culate nucleus, and visual cortex was studied°
DODGE:
B
see Results.
lo Retina"
LSD in high doses
(2°5 mg/kg) decreased the
R_UI.TS'_
amplitude of the response of the optic tract to photic stimulation
of _e retina° In 4 experiments 2°5 mg/kg caused a 7-73% (aVo38%)
decrease. Bufotenine exerted no effect°
2° Lateral geniculate nucleus:
LSD and bufotenine con-
sis_ently and markedly depressed the postsynpatic
response but the
"_"
sensitivity
of
the preparations varied. In 6 experiments 0°2 mg/
k
g
b_tenine
caused a 50-90% (avo 60%) decrease in the amplitude
of
first
of
the postsynaptic spikeso In 5 experiments, 0o03 mg/kg
_aused a 30-100% (avo 80%) decrease° The latency of the maximal
eff_ts
following injection of the drugs varied from 20 seconds to
l_mteo
The first of the postsynaptic spikes show,_the greatest
re_:tion
in amplitude° Asphyxia produced a marked but transitory
ioa_ease in th_ amplitude of the postsynaptic spikes following the
red_:tion
_d_ _egan
_.tude
produced by LSD or bufotenineo
Postsynaptic spike amplit-
to increase within l0 minutes and reached the pre-injectiou
within 1 hour°
3o Visual cortex_
Quantities
of LSD and bufotenine
many
_i_nes greater than those sufficient to alter the electrical activity
of the lateral geniculate nucleus did not decrease the cortical
response to stimulation of optic radiation fibres° However, l0 mg/kg
bufol;enine administered over a 2-hour period or a single injection
of 1o5 mg/kg LSD completely abolished spontaneous cortical act_vi%7o
LSD (0°5 mg/kg) and bufotenine (0°2 mg/kg) decreased the amplitude
of spontaneous cortical
than bufctenine o
activity,
LSD causing
a greater
decrea_eA_
4o General effect s_ The effects of LSD on BoPo and _ %o
respiration differed from those of buf_otenineo In the amounts _
to study geniculate activity_ LSD had no pressor or respirator_ £--_
effects 9 while bufotenine caused a pressor response of 20_40 mm Hg
lasting 2-4 minutes° In the larger quantities used to study cort_l
and tract responses both drugs caused respiratory arrest° For t_
reason9 artificial respiration
with curarization was employed° t_S_
then did not alter BoPo _ even in doses of 2°5 mg/kgo Bufotenine,_
doses of over i mg/kg caused a B_Po rise of approximately 10-159=_Hg
lasting 3_5 minutes°
_u_
5o Co_arison
of effects on retinal versus geniculate_2iv=
i__
The 205 mg/kg I_D which caused an average decrease of 40% _n%_he
amplitude of the tract response is about 80 times as great as the C
0o05 mg/kg LSD which caused an average decrease of 80% in the _$
tude of the postsynaptic geniculate spike° This suggests that #_al
activity is relatively resistant to depression by LSDo A similar eM_
resistance of the retina to bufotenine may be inferred°
sl_
6° Influence of pentobarbitone anaesthesia:
In anim_
that received no barbiturates but were decerebrated by an inter-
collicular section_ LSD and bufotenine produced effects simila_
those in the cat anaesthetized
with pentobarbitone,
although t_q_ I_
dosage required to produce an equivalent effect was 2_5 times _ %(
great°
. ..
(Einige Wirkungen yon LSD und Bufotenin auf die elektrische T_
keit in den Sehzentren und -bahnen der Katze)
_mi'Ie_.
Untersuchungen
an Katzenhl Pentobarbitainarkose
_ber d_ _
elektrophysiologische
Wirkung yon LSD oder Bufotenin (ein Dimet_L
derivat yon Serotonin) auf das Sehzentrum und die zugehSrigen S6_it_
stellen und _bahneno LSD oder Bufotenin intracaro$ideal
hemmt b_'%'
trichtlich die Reaktion des Nucleus geniculatus lateralis (Sch_Xl__
stelle) auf Reizung des Nervus opticus 9 w_hrend die Reaktion d_r_e
Sehzentrums
(Hirnrinde) auf Reizung der Sehstrahlung erhalten #_Do
.....
Die Reaktion des Tractus opticus bei E _nw_rkung yon Lichtre_zen
ube"
auf die Netzhaut wurde durch LSD (in verh_ltn_smass_g hohen Dose_
aber nicht dutch Bufotenin_ gehemmto An decerebrierten Katzen o_e
Pentobarbital
w_rden _hnliche Befunde erhobeno
w7 ED812
.....
(
NKT/DroBs/bh
156 ®_
_'_

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