Search PubMed⌕ Search

Biomedical subjects

M J Rowe

Publications and source records attributed to M J Rowe.

At least 19 recordsLinked to original sources
PubMed1992

Responses of cat ventroposterolateral thalamic neurons to vibrotactile stimulation of forelimb footpads.

Responses of neurons in the ventroposterolateral nucleus of the thalamus to vibration applied to the forelimb footpads were analyzed in anesthetized cats in order to describe the signalling properties of thalamic neurons that received input from the different classes of tactile afferents innervating the glabrous skin of the distal forelimb. Seventy-six thalamic neurons, the majority of which (60 of 76) were positively identified as thalamocortical projection neurons, were classified into two broad groups according to their responses to 1-s step indentations of the skin. A minority (24%) comprised neurons that had slowly adapting (SA) responses, whereas the remainder (76%), the dynamically sensitive neurons, had transient responses to the onset and offset phase of the step and were further classified according to their sensitivity to cutaneous vibrotactile stimuli into those activated by low-frequency vibration (rapidly adapting, RA, neurons) and those activated by high frequencies (Pacinian afferent, PC, neurons). Thalamic RA neurons displayed phaselocked responses to vibration at frequencies up to approximately 100 Hz, while PC neurons displayed phaselocked responses to vibration up to 400-500 Hz. Thalamic SA neurons varied in their responses to vibrotactile stimuli; half were most sensitive to vibration frequencies of 50 Hz or less, while the others responded over a broader range of frequencies. Although three major classes of footpad-related thalamic neurons were identified, there was evidence of convergent input to a small proportion of them. The study demonstrates that thalamic neurons have the capacity for responding to cutaneous vibration with phaselocked, patterned impulse trains, which would enable them to encode information about vibrotactile frequencies up to approximately 300 Hz.

Anesthesia↗
PubMed1992

Vibrotactile sensitivity of slowly adapting type I sensory fibres associated with touch domes in cat hairy skin.

1. Recordings were made from single slowly adapting type I (SAI) afferent fibres associated with touch domes in the cat hairy skin. Controlled vibratory stimuli were used first, to characterize the precision with which these SAI afferents reflect the temporal aspects of vibrotactile stimuli, and second, to determine whether earlier disparate reports of SAI responsiveness to vibration may be attributable to highly specific stimulus requirements. 2. Eighteen SAI fibres from femoral cutaneous nerve branches were examined; each was associated with one to three touch domes. SAI responses to both steps and sinusoidal vibration (1-1.5 s in duration) were affected profoundly by both probe size and position. Punctate stimulus probes (250 microns) produced much higher response levels and steeper stimulus-response relations than those elicited with large (2 mm) probes, probably on account of focal distortion created within the dome by the smaller probes. SAI sensitivity to vibration was also affected markedly by the amplitude of any pre-indentation on which the vibration was superimposed; sensitivity was much lower when the pre-indentation exceeded 100 microns, in particular with larger stimulus probes. 3. Measures of both vibration sensitivity and the precision of impulse patterning demonstrated that, if appropriate stimulus parameters are chosen, the SAI fibres can respond to 1 s trains of vibration (amplitude < or = 100 microns) in a tightly phase-locked, 1:1 manner for frequencies up to 500 Hz. At frequencies from approximately 100-500 Hz the SAI fibres displayed broad 1:1 plateaus, where their response rate remained constant over a range of amplitudes, and phased-locking was tightest. Responses remained phase-locked up to 1000 Hz, but could not follow the vibration with a 1:1 pattern above 500 Hz. 4. The results demonstrate that with appropriate stimulus parameters, touch dome-associated SAI fibres are capable of signalling vibrotactile information over a similar bandwidth of frequencies as do Pacinian sensory fibres. The variability in past reports of SAI vibration sensitivity may relate principally to differences in stimulus conditions. However, in view of the SAI capacity for responding to vibration with temporally precise, patterned activity, it appears that their reported failure to contribute to vibrotactile sensibility must be attributed to limitations imposed in the central processing of SAI signals.

Animals↗
PubMed1992

Responses of slowly adapting type II afferent fibres in cat hairy skin to vibrotactile stimuli.

1. Slowly adapting type II (SAII) afferent fibres that supply the forelimb were isolated from the medial cutaneous nerve of anaesthetized cats and examined for their capacity to signal information about vibrotactile events in the hairy skin. 2. The SAII fibres had a single spot-like receptive field focus where they were highly sensitive to steady indentation and vibration applied with probes normal to the skin surface. However, their sensitivity was affected profoundly by the size of the stimulus probe, its position in relation to the receptive field focus and, to a lesser extent, the magnitude of any pre-indentation on which vibration was superimposed. Small stimulus probes (e.g. 250 microns diameter) were much more effective than larger (> or = 1-2 mm) ones, and small shifts in the position of the perpendicularly applied probe away from the receptive field focus led to a marked decline in responsiveness. 3. With appropriate choice of stimulus parameters for vibratory stimuli applied at the receptive field focus, the SAII fibres could respond at low threshold (< 100 microns), with a tightly phase-locked, regular 1:1 impulse pattern (one impulse per vibration cycle) that accurately signalled the vibration frequency over a bandwidth that extended to 600 Hz. Furthermore, their responses remained phase-locked up to 1000 Hz. Phase-locking in SAII fibres was marginally tighter than that in SAI fibres and comparable to that of Pacinian corpuscle fibres. 4. The sensitivity of forelimb SAII fibres to tangential skin stretch was directionally selective; stretch across the forelimb was much more effective than along its long axis. Vibration associated with tangential skin stretch led to a marked spatial expansion of the field of vibration sensitivity. SAII fibres could therefore signal information about natural stimuli that contain elements of skin stretch and vibration, as may be encountered when the forelimb brushes against textured surfaces. Should the SAII fibres fail to contribute to the sensory experience of vibrotactile stimuli, the explanation may be related to limitations imposed centrally on the processing of their signals. Nevertheless, the present results demonstrate that, with appropriate stimulus conditions, the SAII afferent fibres have much greater vibrotactile sensitivity than has been suggested by past studies.

Action Potentials↗
PubMed1992

Parallel processing of tactile information in the cerebral cortex of the cat: effect of reversible inactivation of SI on responsiveness of SII neurons.

1. Localized cortical cooling was employed in anesthetized cats for the rapid reversible inactivation of the distal forelimb region within the primary somatosensory cortex (SI). The aim was to examine the responsiveness of individual neurons in the second somatosensory area (SII) in association with SI inactivation to evaluate the relative importance for tactile processing of the direct thalamocortical projection to SII and the indirect projection from the thalamus to SII via an intracortical path through SI. 2. Response features were examined quantitatively before, during, and after SI inactivation for 29 SII neurons, the tactile receptive fields of which were on the glabrous or hairy skin of the distal forelimb. Controlled mechanical stimuli that consisted of l-s trains of either sinusoidal vibration or rectangular pulses were delivered to the skin by means of small circular probes (4- to 8-mm diam). 3. Twenty-three of the 29 SII neurons (80%) showed no change in response level (in impulses per second) as a result of SI inactivation. These included seven neurons activated exclusively or predominantly by Pacinian corpuscle (PC) receptors, six that received hair follicle input, four activated by convergent input from hairy and glabrous skin, and six driven by dynamically sensitive but non-PC inputs from the glabrous skin. 4. Six SII neurons (20%), also made up of different functional classes, displayed a reduction in response to cutaneous stimuli when SI was inactivated. 5. Stimulus-response relations, constructed by plotting response level in impulses per second against the amplitude of the mechanical stimulus, showed that the effect of SI inactivation on individual neurons was consistent over the whole response range. 6. The reduced response level seen in 20% of SII neurons in association with SI inactivation cannot be attributed to direct spread of cooling from SI to the forelimb area of SII, as there was no evidence for a cooling-induced prolongation in SII spike waveforms, an effect that is known to precede any cooling-induced reduction in responsiveness. 7. As SI inactivation produced a fall in spontaneous activity in the affected SII neurons, we suggest that the inactivation removes a source of background facilitatory influence that arises in SI and affects a small proportion of SII neurons. 8. Phase-locking and therefore the precision of impulse patterning were unchanged in the responses of SII neurons to vibration during SI inactivation. This was the case whether response levels of neurons were reduced or unchanged by SI inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Parallel processing in rabbit first (SI) and second (SII) somatosensory cortical areas: effects of reversible inactivation by cooling of SI on responses in SII.

1. Previous observations on the effect of ablation or inactivation of the primary somatosensory cortex (SI) on the responses of neurons within the second somatosensory area (SII) to tactile stimuli point to profound differences between monkeys and certain other mammals in the organization of thalamocortical systems. In the cat, for example, tactile information appears to be conveyed in parallel from the thalamus to both SI and SII, whereas, in macaque and marmoset monkeys, it is conveyed in a serial (or hierarchical) scheme from the thalamus to SI and thence to SII. The present study examined the responses of individual SII neurons during reversible, cooling-induced inactivation of SI in another nonprimate placental mammal, the rabbit, to obtain further evidence on whether the above differences might reflect a fundamental distinction between simian primates and other mammalian species. 2. When the temperature at the face of a silver cooling block over the forepaw and hindpaw regions of SI was lowered to 5-13 degrees C, the SI surface potentials evoked by brief tactile stimuli were abolished (indicative of SI inactivation), whereas SII potentials remained intact. 3. The responses of 25 SII neurons to controlled tactile stimuli (consisting of 1- to 1.5-s trains of vibration or rectangular mechanical pulses) were studied before, during, and after inactivation of SI. The effects on the spontaneous activity of a further three SII neurons that lacked identified receptive fields were also studied. 4. The response or activity levels of 26 of the 28 SII neurons examined (93%) were unaffected by SI inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

A method for the generation of complex vibrotactile stimuli.

A method is described utilizing computer-generated sine wave data and purpose-built hardware to generate a complex vibrotactile stimulus. Two sine waves of different frequency were summed to produce a complex waveform with two temporal components, a high frequency component and a low frequency beat component. The computer-generated data points for each of the two component sine waves were downloaded to two banks of static memory in a dual synchronous arbitrary function generator. The data points in memory were fed to two 12-bit digital-to-analogue converters which sent the two analogue sine wave signals to a summing amplifier where the two sine waves were added. This method provides a complex waveform that can be gated on and off, has a fixed frequency ratio of the component sine waves and no phase drift between the component waves. Addition of the separate sine waves in a summing amplifier allows for easy alteration of the amplitude ratio of the sine waves. The output of the summing amplifier is sent to a feedback controlled mechanical stimulator, thereby allowing the stimulus to be presented to the skin of human subjects and experimental animals.

Computers↗
PubMed1990

Perceived pitch of vibrotactile stimuli: effects of vibration amplitude, and implications for vibration frequency coding.

1. The effect of changes in amplitude on the perceived pitch of cutaneous vibratory stimuli was studied in psychophysical experiments designed to test whether the coding of information about the frequency of the vibration might be based on the ratio of recruitment of the PC (Pacinian corpuscle-associated) and RA (rapidly adapting) classes of tactile sensory fibres. The study was based on previous data which show that at certain vibration frequencies (e.g. 150 Hz) the ratio of recruitment of the PC and RA classes should vary as a function of vibration amplitude. 2. Sinusoidal vibration at either 30 Hz or 150 Hz, and at an amplitude 10 dB above subjective detection thresholds was delivered in a 1 s train to the distal phalangeal pad of the index finger in eight human subjects. This standard vibration was followed after 0.5 s by a 1 s comparison train of vibration which (unknown to the subject) was at the same frequency as the standard but at a range of amplitudes from 2 to 50 dB above the detection threshold. A two-alternative forced-choice procedure was used in which the subject had to indicate whether the comparison stimulus was higher or lower in pitch (frequency) than the standard. 3. Marked differences were seen from subject to subject in the effect of amplitude on perceived pitch at both 30 Hz and 150 Hz. At 150 Hz, five out of the eight subjects reported an increase in pitch as the amplitude of the comparison vibration increased, one experienced no change, and only two experienced the fall in perceived pitch that is predicted if the proposed ratio code contributes to vibrotactile pitch judgements. At 30 Hz similar intersubject variability was seen in the pitch-amplitude functions. 4. The results do not support the hypothesis that a ratio code contributes to vibrotactile pitch perception. We conclude that temporal patterning of impulse activity remains the major candidate code for pitch perception, at least over a substantial part of the vibrotactile frequency bandwidth.

Female↗
PubMed1988

Representation of forelimb mechanoreceptors within the superior colliculus of the cat.

Forelimb mechanoreceptor representation within the superior colliculus was investigated using microelectrode recording in decerebrate or anaesthetized cats. Selective activation of different mechanoreceptive fibre classes supplying the distal forelimb revealed a poor representation of all three fibre classes (SA, PC and RA) that innervate the glabrous skin. Furthermore, there was no evidence for Pacinian (PC) input from the interosseous or wrist region. The tap stimuli which are often needed to activate the collicular neurones, may be effective, when applied to the distal limb, because of stimulus spread to more proximal sites, or as a result of the synchronous recruitment of multiple classes of afferent fibres.

Animals↗
PubMed1988

Neural mechanisms in vibrotactile adaptation.

1. Peripheral and central neural contributions to vibrotactile adaptation were investigated in decerebrate or anesthetized cats by recording from sensory nerve fibers associated with Pacinian corpuscle (PC) receptors and from central neurons of the dorsal column nuclei that receive their input from vibration-sensitive receptors of the forelimb footpads. Responsiveness of units was assessed using 1-s duration, test vibration stimuli delivered with 1- to 2-mm-diam probes at different times following adapting trains of vibration (usually 300 Hz) that lasted from less than 1 min up to 50 min. 2. Cuneate neuron responsiveness underwent marked depression following prior vibration. The extent of the depression and the time course of recovery in responsiveness were dependent on the intensity and duration of the adapting vibratory stimulus. The recovery time course (often several minutes) was approximately exponential and resembled the reported time course of subjective vibrotactile adaptation obtained in psychophysical experiments. 3. Response depression in PC fibers was only seen at low amplitudes of the test vibration and displayed a brief time course of recovery in comparison with that seen in cuneate neurons. It is therefore unlikely to account for the adaptation time course either in cuneate neurons or at a subjective level. Furthermore, as the adaptation seen in PC fiber responses had a similar time course in both cutaneous and mesenteric PC fibers it is unlikely that mechanical changes in the skin contribute significantly to the adaptation in PC fiber responses to vibration. 4. The time course of afferent-induced inhibition following long periods of prior vibration was too brief to account for the response adaptation in cuneate neurons. 5. As the long-term response depression in cuneate neurons following their prior activation was seen for inputs from unconditioned sites within the neuron's excitatory receptive field, as well as from the conditioned site, it appears that the response adaptation is attributable to changes in the central neuron or in synaptic processes associated with the central neuron. It is proposed that this adaptation may be due to an increase in extracellular potassium ion concentration that alters the responsiveness of the central neurons.

Adaptation, Physiological↗
PubMed1988

Comparing state-only expenditures for AIDS.

The State AIDS Policy Center at the Inter-governmental Health Policy Project (IHPP) at George Washington University surveyed all 50 states to determine state AIDS (acquired immunodeficiency syndrome) expenditures, without Medicaid or federal funds, for fiscal 1984-88. During this period, state-only expenditures increased 15-fold, to $156.3 million. Between fiscal 1986-1988, the distribution of state funding for AIDS patient care and support services doubled from 16 to 35 per cent and the number of states supplementing federal funds for testing and counseling increased from eight to 20. Five states continue to account for the largest AIDS appropriations. Of these, California leads in funding research; New York, Florida, and New Jersey have directed funds to provide care and services to IV (intravenous) drug users, prisoners, and children. The average state expenditure per diagnosed AIDS case is $3,323 and an increasing number of states with relatively low case loads are appropriating funds beyond this level. Across states, AIDS expenditures per person average $.65 and $.21 for education, testing and counseling--below the level recommended by the Institute of Medicine for AIDS prevention activities. Some jurisdictions support AIDS activities indirectly by shifting resources, often from their STD (sexually transmitted disease) programs--this trend deserves continuing review given the rise in STD cases and their relationship to diagnosed AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Phase coherence in vibration-induced responses of tactile fibres associated with Pacinian corpuscle receptors in the cat.

1. In pentobarbitone-anaesthetized cats, responses were recorded in peripheral nerves or cervical dorsal columns from sensory fibres associated with Pacinian corpuscle (P.c.) receptors in the forelimb footpads. Factors affecting the phase of response to cutaneous vibration in individual P.c. fibres, and the extent of phase coherence in the responses of different P.c. fibres were examined when sinusoidal vibratory stimuli at 100-400 Hz were delivered using a 1 mm diameter probe. 2. Increases in vibration amplitude from the absolute to the 1:1 threshold for the P.c. fibre led to phase advances in the response, often of about 60 deg, in over 85% of fibres tested at 200 and 300 Hz, but further increases had little effect. 3. Variations in stimulus position within the receptive field led to unpredictable changes in the response phase that ranged from minimal change to shifts of 180 deg. As the response phase was unrelated to the distance from the point of peak sensitivity it is likely that at high vibration frequencies (greater than or equal to 100 Hz) the recruited population of P.c. fibres will respond over the whole range of phase angles. 4. The calculated phase of spike initiation in different pairs of P.c. fibres that shared coincident points of best sensitivity on the skin ranged from near synchrony to maximum asynchrony indicating that there is little phase coherence even in the subpopulation of somatotopically related P.c. fibres recruited by high-frequency cutaneous vibration. 5. Paired recordings from P.c. fibres within the cervical dorsal columns revealed a broad range of phase discrepancies in the responses of P.c. fibres to vibration at 200 and 300 Hz. 6. Several hypotheses are considered to explain the known presence of phase-locked responses to high-frequency (greater than or equal to 100 Hz) vibration in the central neurones of dorsal column nuclei.

Action Potentials↗
PubMed1987

Temporal patterning in the responses of gracile and cuneate neurones in the cat to cutaneous vibration.

1. Recordings were made in decerebrate cats from gracile and cuneate neurones responding to vibration-induced inputs from Pacinian corpuscle (P.c.) receptors of the hind-limb and forelimb footpads. The two groups of neurones were compared, in particular for their capacities for responding to cutaneous vibration with phase-locked impulse patterns. 2. In both nuclei the P.c. neurones were most sensitive to vibration in the range 80 to greater than 600 Hz. Stimulus-response relations were similar for the two groups, as were measures derived from these relations such as response levels, absolute thresholds and the dynamic range (defined as the vibration amplitude range over which responses were graded). 3. At frequencies up to 300-400 Hz, responses for some neurones in both nuclei remained well phase locked to the vibration; however, quantitative analysis using a factorial analysis of variance indicated that the phase locking was poorer in gracile than cuneate neurones. 4. In both nuclei there was marked variability from neurone to neurone in measures of phase locking which may reflect variations in the extent of convergence of P.c. fibres upon different target neurones. For neurones in either nucleus that had comparatively tight phase locking of responses to vibration it is proposed that their output is functionally dominated by one or a few of their convergent P.c. input fibres.

Action Potentials↗
PubMed1987

Actions of single sensory fibres on cat dorsal column nuclei neurones: vibratory signalling in a one-to-one linkage.

1. The synaptic linkage between single, identified sensory fibres associated with Pacinian corpuscle (P.c.) receptors and central neurones of the dorsal column nuclei was examined in decerebrate or anaesthetized cats. Paired recordings were made from individual neurones in the gracile division of the dorsal column nuclei and from the hind-limb interosseous nerve in which it is possible to identify and monitor the activity of each P.c. fibre activated when recording from the intact nerve with a platinum hook electrode. Individual P.c. fibres were activated by vibration delivered with an 0.2 mm diameter probe to the interosseous P.c. receptors. 2. Thirty-five P.c. fibre-gracile neurone pairs were isolated in which activity in the single, identified P.c. fibre evoked suprathreshold responses (mean latency +/- S.D., 10.3 +/- 1.5 ms) in the gracile neurone. A single impulse arriving over one P.c. fibre could generate pairs or triplets of output spikes from several target neurones thus revealing a potent synaptic organization within the dorsal column nuclei for the transmission and amplification of weak sensory signals. 3. The potency of the linkage for some pairs resulted in post-synaptic response levels of up to 400 impulses s-1 when a single input fibre was discharging one impulse on each vibration cycle at 200-400 Hz. 4. Gracile neurones driven by single P.c. fibres had phase-locked responses to vibration at frequencies of up to 400-500 Hz. However, the responses displayed much greater phase dispersion than those of P.c. fibres, indicating that a major component of phase dispersion in the vibration-induced responses of dorsal column nuclei neurones is attributable to the properties of the synaptic linkage between an individual fibre and the target neurone. 5. The potent actions of single, identified P.c. fibres on their target neurones are consistent with the hypothesis that phase-locked responses in dorsal column nuclei neurones to vibration at 100-400 Hz may reflect the functional domination of the target neurone's output by one or a few of its converging fibres.

Action Potentials↗
PubMed1987

Integrative processing of vibratory information in cat dorsal column nuclei neurones driven by identified sensory fibres.

1. In decerebrate or anaesthetized cats, the vibration-induced responses of dorsal column nuclei neurones were examined, first, when their input came from simultaneously recorded pairs or other combinations of identified Pacinian corpuscle (P.c.) afferent fibres of the interosseous nerve, and secondly, when different convergent sets of P.c. fibres were engaged by footpad vibration. 2. Suprathreshold actions were observed on individual dorsal column nuclei neurones from two or more identified P.c. fibres. Recruitment of these convergent fibres usually led to summation in the dorsal column nuclei neurone as reflected in higher response levels compared with those evoked by single-fibre inputs. 3. When the input was increased from one to two or more identified P.c. fibres the dorsal column nuclei neurones could retain a single, dominant phase of response to high-frequency (greater than 100 Hz) vibration even though these fibres, in isolation, evoked responses in the target neurone at substantially different latencies. However, on average, phase locking was significantly tighter in response to single-fibre input than to multiple P.c.-fibre input. 4. Dorsal column nuclei neurones were also able to retain phase-locked responses to high-frequency vibration when phase differences between different convergent inputs were systematically introduced to alter the degree of synchrony in the activity arriving over convergent, identified P.c. fibres. 5. When the input to dorsal column nuclei neurones came from the skin it was found that with the recruitment of two converging sets of P.c. fibres the dorsal column nuclei neurones were able to retain phase-locked responses to high-frequency vibration even when phase shifts were introduced between the two sets of P.c. inputs. 6. In conclusion, the observed integrative processing by dorsal column nuclei neurones of vibration-induced inputs arriving over identified, convergent P.c. fibres, or sets of P.c. fibres, is consistent with our hypothesis that the retention of phase-locked responses to vibration at frequencies greater than or equal to 100 Hz may reflect the functional domination of the target neurone by just one or a few of its convergent input fibres.

Action Potentials↗
PubMed1986

High gain transmission of single impulses through dorsal column nuclei of the cat.

Paired recordings were made in the cat from neurones of dorsal column nuclei and from intact pacinian sensory fibres of the hindlimb interosseous nerve. Direct evidence is presented for central neurones being driven by single impulses arriving over just one sensory nerve fibre. Transmission through this sensory relay appears to be optimized for the detection of minimal sensory inputs. Two mechanisms operate for the amplification of such inputs. First, individual sensory fibres can exert divergent, suprathreshold actions on multiple target neurones, and second, a single impulse coming over one input fibre can induce pairs or bursts of output spikes from its target neurones.

Afferent Pathways↗
PubMed1986

Suppression of endocytosis in neutrophils by influenza A virus in vitro.

The effect of influenza A virus on the endocytic pathway in polymorphonuclear leukocytes (PMNLs) and the relationship of altered endocytic activity to virus-induced inhibition of other PMNL functions were examined with virus that caused decreased phagosomelysosome fusion and bacterial killing (depressing virus [DV]) and virus that did not (non-DV). Binding of both viruses to PMNL surface receptors was similar, but uptake of DV into PMNLs was decreased compared with that of non-DV. Both viruses were associated with the PMNL plasma membrane and were in endosomes. DV caused less stimulation of pinocytosis than did non-DV. The rate of exocytosis of fluoresceinated-dextran (FL-dextran) from cells stimulated with DV was significantly less than for non-DV. When PMNLs were pretreated with buffer, DV, or non-DV and then exposed to FL-dextran and N-formylmethionylleucylphenylalanine, the pinocytosis of FL-dextran was significantly less in cells pretreated with DV as compared with non-DV or buffer.

Endocytosis↗
PubMed1986

Luteinization-specific ovarian mitochondrial proteins.

Mitochondria isolated from porcine medium- and large-sized ovarian follicles and corpora lutea show progressive increases in specific proteins temporally associated with luteinization. These include 12-15, 16-17, 33, 47, 50, and 60 kDa proteins. Synthesis of these same mitochondrial proteins is stimulated by incubation of large ovarian follicles with luteinizing hormone (LH) (0.10 microgram/ml) but not by follicle-stimulating hormone (0.10 microgram/ml). A dose-response curve was generated indicating that synthesis of several mitochondrial proteins is stimulated in an LH-dependent manner, while synthesis of two appear to be repressed (70 and 94 kDa). Examination of mitochondrial translation products (cycloheximide-insensitive, chloramphenicol-sensitive protein synthesis) from isolated follicular and luteal mitochondria, by both one- and two-dimensional electrophoresis, demonstrated that two proteins (23 and 35 kDa) are synthesized within luteal but not follicular mitochondria. Further, synthesis of two proteins within follicular mitochondria are significantly reduced in luteal mitochondrial. Regulation of mitochondrial proteins necessary for the rate-limiting step in steroidogenesis is discussed.

Animals↗