Relationship between taenia coli electric activity and circular fibers. Study of the human transverse colon

First results of the comparison between the electrical activity of taenia coli and circular muscle are described. Experimental techniques consisted in recording electrical activity for 83 h in 12 patients during the post-operative period after cholecystectomy. Bipolar wire electrodes were surgically inserted in each muscle of the transverse colon's median portion. Statistical treatment leads to the principal conclusion as follows: Whatever type of muscles we have investigated, always could be found slow rhythmic components (called electro-control activity, ECA) in frequency ranges of 1-5 c/min and 9-12 c/min. Major part of taenia coli ECA is in frequency range between 1-5 c/min. ECA in this frequency range can be found in 21% of circular ECA, 23% of taenia coli ECA and 9% of common ECA (% means percents of total recording time). Higher frequencies are found in 7% of circular ECA, 4% of taenia coli ECA and 3% of common ECA. Using long time constant (more than 2 s) the bursts of spikes (10-50 microV) meaning active responses are always accompanied with slower components of important amplitude (greater than or equal to 100 microV): In the discrete mode of activity (DERA) short bursts (during 1-2.5 s) always follow the ECA, whereas in the continuous mode of activity (CERA) mostly longlasting bursts (up to 30 s) could be found. The bursts represent 14% of total time, namely in 8% of longitudinal ECA, 4% of circular ECA and 2% of common ECA. ECA of taenia coli in the case of common ECA is always prolonged. Typical slow waves of greater amplitude (greater than or equal to 500 microV) different from ECA are frequently recorded probably due the intensive contractile process.     

Mechanisms underlying nutrient-induced segmentation in isolated guinea pig small intestine

Mechanisms underlying nutrient-induced segmentation within the gut are not well understood. We have shown that decanoic acid and some amino acids induce neurally dependent segmentation in guinea pig small intestine in vitro. This study examined the neural mechanisms underlying segmentation in the circular muscle and whether the timing of segmentation contractions also depends on slow waves. Decanoic acid (1 mM) was infused into the lumen of guinea pig duodenum and jejunum. Video imaging was used to monitor intestinal diameter as a function of both longitudinal position and time. Circular muscle electrical activity was recorded by using suction electrodes. Recordings from sites of segmenting contractions showed they are always associated with excitatory junction potentials leading to action potentials. Recordings from sites oral and anal to segmenting contractions revealed inhibitory junction potentials that were time locked to those contractions. Slow waves were never observed underlying segmenting contractions. In paralyzed preparations, intracellular recording revealed that slow-wave frequency was highly consistent at 19.5 (SD 1.4) cycles per minute (c/min) in duodenum and 16.6 (SD 1.1) c/min in jejunum. By contrast, the frequencies of segmenting contractions varied widely (duodenum: 3.6-28.8 c/min, median 10.8 c/min; jejunum: 3.0-27.0 c/min, median 7.8 c/min) and sometimes exceeded slow-wave frequencies for that region. Thus nutrient-induced segmentation contractions in guinea pig small intestine do not depend on slow-wave activity. Rather they result from a neural circuit producing rhythmic localized activity in excitatory motor neurons, while simultaneously activating surrounding inhibitory motor neurons.     

Relation between the electrical and mechanical activity of the stomach. In situ study of the anesthetized rat

The relations between the electrical and mechanical activity of the corpus and the antrum have been studied by means of several microelectrodes and enterographic transducer under binocular control (X 5) in anaesthetized rats (pentobarbital Na, 4 mg/kg). The recording period starts from 30 min after the onset of anaesthesia. This time corresponds to the release of the post operative inhibitions. Several rhythms of slow components have been in evidence thanks to a long time constant (5 sec): the dominant component with his frequency 4.04 +/- 1.06 c/min (n = 302 values). This frequency increases (5.11 +/- 1.3 c/min) during the antropyloric evacuation. Other rhythmic components of smaller amplitude (less than 200 microV) and frequency ranging between 7-16 c/min have been seen in quiescent conditions. In contractile state, the incidence of such rhythms decreases. The weakest manifestations of mechanical activity consist of small rhythmic variations of volume, the frequency corresponding to the main gastric rhythm of 4.5 c/min; however any spiking activity is observed. The second step of activity is the peristalsis (speed: 1 mm/sec), the circular contractility is accompanied by small spikes (less than 200 microV) in short salves. The third step is marked by the antral contraction with an important volume of variation, spike bursts of greater amplitude and biphasic slow wave are recorded. The antral activity is followed by a break of the main rhythm activity during 20 sec. These activities appear as a result from a structuration of local oscillators of relatively high frequency, in this species.     

The release of catecholamines from the adrenal medulla and its modulation by alpha 2-adrenoceptors in the anaesthetized dog

The adrenal nerve of anaesthetized and vagotomized dogs was electrically stimulated (10 V pulses of 2 ms duration for 10 min) at frequencies of 1, 3, 10, and 25 Hz. There was a correlation between the frequency of stimulation and the plasma concentrations of epinephrine, norepinephrine, and dopamine in the adrenal vein, mainly after the 1st min of stimulation and the maximal concentration was reached sooner with higher frequencies of stimulation. Moreover, the relative percentage of catecholamines released in response to the electrical stimulation was not changed by the frequency of stimulation. To test the hypothesis that a local negative feedback mechanism mediated by alpha 2-adrenoceptors exists in the adrenal medulla, the effects of the systemic administration of clonidine (alpha 2-antagonist) on the concentrations of catecholamines in the adrenal vein were evaluated during the electrical stimulation of the adrenal nerve (5 V pulses of 2 ms duration for 3 min) at 3 Hz. Moreover, the effects of the systemic injections of more specific alpha 2-agonist and antagonist (oxymetazoline and idazoxan) were tested on the release of catecholamines in the adrenal vein in response to electrical stimulation of the splanchnic nerve at 1 and 3 Hz frequencies. The injection of 0.5 mg/kg of yohimbine caused a significant increase in the concentrations of epinephrine and norepinephrine in the adrenal vein induced by the electrical stimulation of the adrenal nerve and the injection of 15 micrograms/kg of clonidine had no effects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spectral correlation analysis of the potentials of the neocortex and certain subcortical structures during low-frequency electrical stimulation of nonspecific thalamic nuclei]

The spectral-correlation analysis of biopotentials in the cortex and some other brain structures (the anteroventral thalamic nucleus, dorsal hippocampus, lateral geniculate body, mid-brain reticular formation), in chronic experiments on alert rabbits, revealed that during electrical stimulation of thalamic mid-line nuclei within the ranges of 1-3, 4-7 and 8-10 c/s, there occured a rearrangement of the EEG frequencies; a dominant, narrow-band peak at the stimulation frequency, appeared. The coherence of the biopotentials of different cortical areas, of the cortex and subcortical formations increased during the stimulation at the frequency of the stimulation, reaching maximum values between the potentials of the visual and sensorimotor cortical areas.     

AMP-activated protein kinase kinase activity and phosphorylation of AMP-activated protein kinase in contracting muscle of sedentary and endurance-trained rats

This study was designed to examine activity of AMP-activated protein kinase kinase (AMPKK) in muscles from nontrained and endurance-trained rats. Rats were trained 5 days/wk, 2 h/day for 8 wk at a final intensity of 32 m/min up a 15% grade with 30-s sprints at 53 m/min every 10 min. Gastrocnemius muscles were stimulated in situ in trained and nontrained rats for 5 min at frequencies of 0.4/s and 1/s. Gastrocnemius LKB1 protein, a putative component of the AMPKK complex (LKB1, STRAD, and MO25), increased approximately twofold in response to training. Phosphorylation of AMP-activated protein kinase (AMPK) determined by Western blot and AMPK activity of immunoprecipitates (both isoforms) was increased at both stimulation rates in both trained and nontrained muscles. AMPKK activity was 73% lower in resuspended polyethylene glycol precipitates of muscle extracts from the trained compared with nontrained rats. AMPKK activity did not increase in either trained or nontrained muscle in response to electrical stimulation, even though phospho-AMPK did increase. These results suggest that AMPKK is activated during electrical stimulation of both trained and nontrained muscle by mechanisms other than covalent modification.     

Repeated characterization, analysis of variance limitation and discrimination analysis classification of EEG-activity patterns in human sleep]

1. To describe quantitatively and to deliminate nine EEG sleep patterns, mean values and standard deviations of abundances of the frequencies 0.8 ... 1.8 c/sec, 2...3.5 c/sec, 4...13c/sec, 14 to 17 c/sec, 18 to 22 c/sec, and 23 to 40 c/sec as well as of the average amplitudes in selected frequency ranges were calaculated and the distributions represented. 2. All nine EEG activity patterns could be separated by means of univariate and multivariate analyses of variance on the basis of all 28 as well as the 17 indispensable variables. 3. In the course of a stepwise reduction of variables within the framework of a linear discriminant analysis an optimal set of 17 variables was determined for the separation of the patterns, comprising: the percent quantity of the frequencies 0.8 ... 3.5 c/sec, 7 ... 9 c/sec and 18 to 40 c/sec as well as the average amplitudes in the frequency ranges 0.8 to 3.5 c/sec and 7.5 to 40 c/sec. 4. By linear regression analyses it could be shown that the sleep scording system used, can be reflected on an interval scale with the aid of discriminant functions; this can be achieved on the basis of the optimal set of variables as well as of the five most indispensable variables. 5. Finally the degree of the objectivity of the scoring procedures was demonstrated. Advantages and disadvantages of sleep scoring systems were discussed and possibilities of the utilization of results suggested, also in respect to the further development of the automatic recognition of EEG activity patterns.     

Formation of linear relations of potentials in the dog neocortex in a dynamic stereotype]

During elaboration of a stereotype system of defensive conditioned reflexes in dogs (Pavlov dynamic stereotype), a correlation spectral analysis was made of electrical activity in the neocortex. With a stable dynamic stereotype, substantial changes of background electrical activity were observed in the interstimuli periods, manifested in a significant growth of linear relations of cortical potentials at certain frequencies. This was expressed in separation from the wide-band random process (involving background activity before the formation of the dynamic stereotype) of definite, relatively narrow ranges of frequencies which formed the high coherence of the processes. No such changes of electrical activity were observed in conditioning without a stereotype; this points to special mechanisms of the dynamic stereotype, which differ from those of ordinary conditioned reflexes.     

Actigraphy: A Means of Assessing Circadian Patterns in Human Activity

-Twenty-three diurnally active (0705-2333), healthy persons between 22 and 54 yrs of age and without history of sleep abnormality were monitored continuously for 120 consecutive hr (five days) by wrist actigraphy. Circadian rhythms of high amplitude were detected by cosinor analysis for each participant and for the groups of 10 males and 13 females with the average span of heightened activity timed between ∼1330 and 1605. The circadian peak-trough difference in wrist movement was marked, equalling aproximately 75% of the 24-hr mean level. In 19 of 23 participants, the 24-hr mean of wrist activity varied between 140-180 movements/min, with four persons exhibiting lesser means of 110-140 movements/min. With respect to the daytime span of activity, the mean wrist movement of individual participants ranged from 155-265 movements/min, with the majority (20/23) varying between 185-245 movements/min. During nocturnal sleep the mean wrist activity level was quite low, varying between individuals from 5 to 25 movements/min for 21 of 23 persons. Wrist actigraphy proved to be well-accepted and was a most reliable means of monitoring aspects of body movement during activity and sleep in ambulatory persons adhering to usual life habits and pursuits.     

Natural Pseudomonas sp. strain N3 in artificial soil microcosms

The lightning-competent Pseudomonas sp. strain N3, recently isolated from soil, has been used to study the extent of natural electrotransformation (NET) or lightning transformation as a horizontal gene transfer mechanism in soil. The variation of electrical fields applied to the soil with a laboratory-scale lightning system provides an estimate of the volume of soil affected by NET. Based on the range of the electric field that induces NET of Pseudomonas strain N3, the volume of soil, where NET could occur, ranges from 2 to 950 m(3) per lightning strike. The influence of DNA parameters (amount, size, and purity) and DNA soil residence time were also investigated. NET frequencies (electrotransformants/recipient cells) ranged from 10(-8) for cell lysate after 1 day of residence in soil to 4 x 10(-7) with a purified plasmid added immediately before the lightning. The electrical field gradient (in kilovolts per cm) also played a role as NET frequencies ranging from 1 x 10(-5) at 2.3 kV/cm to 1.7 x 10(-4) at 6.5 kV/cm.     

Resting EEG effects during exposure to a pulsed ELF magnetic field

Continuing evidence suggests that extremely low frequency magnetic fields (ELF MFs) can affect animal and human behavior. We have previously demonstrated that after a 15 min exposure to a pulsed ELF MF, with most power at frequencies between 0 and 500 Hz, human brain electrical activity is affected as measured by electroencephalography (EEG), specifically within the alpha frequency (8-13 Hz). Here, we report that a pulsed ELF MF affects the human EEG during the exposure period. Twenty subjects (10 males; 10 females) received both a magnetic field and a sham session of 15 min in a counterbalanced design. Analysis of variance (ANOVA) revealed that alpha activity was significantly lower over the occipital electrodes (O1, Oz, O2) [F(1,16) = 5.376, P < .01, eta2 = 0.418] after the first 5 min of magnetic field exposure and was found to be related to the order of exposure (MF-sham vs. sham-MF). This decrease in alpha activity was no longer significant in the 1st min post-exposure, compared to sham (P > .05). This study is among the first to assess EEG frequency changes during a weak (+/-200 microTpk), pulsed ELF MF exposure.     

Stimulation of the hippocampus and its effect on electrographic manifestations of the brain in unrestrained rats.

The dorsal hippocampus was electrically stimulated in unanaesthetized, unrestrained rats with a cobalt-gelatin rod in their cortex. The significance of the hippocampus in the elicitation of both physiological spontaneous rhythmic activity (episodic activity of 8--9/sec frequency bound, in rats, to a state of quiet wakefulness, and "sleep spindles") and pathological rhythmic activity of the self-sustained after-discharge (SSAD) type was determined from the aspect of the EEG and behavioural characteristics. 1. Single electrical pulses (0.1 msec, 1--10 V, 0.3/sec) elicited an evoked potential bilaterally in the somatosensory cortex. Elicitation of rhythmic after-activity (of the type of episodes or sleep spindles) was observed only in some cases in which an adequately strong stimulus was used. 2. Repeated series of rhythmic electrical stimuli following each other at short intervals (2--3 min) led to the formation of SSAD in about one third of the cases and at all stimulation frequencies (3-15/sec), although low frequencies (3--4/sec) were the least effective. The character of the SSAD and simultaneous behavioural phenomena differed fundamentally from those evoked by electrical stimulation of the thalamus (Chocholová et al. 1977). The development of paroxysmal after-activity was signalled by responses of a more or less distinct "recruiting" character during stimulation. On the basis of a comparison of electrographic and behavioural manifestations after electrical stimulation of the thalamus and hippocampus, the possibility of both thalamic and extrathalamic projection from the hippocampus to the cortical region is considered.     

Age-variant and age-invariant rhythmicities in the cortical and hippocampal electrical activities of neonatal rats.

The neocortical and hippocampal electrical activities were studied in 8, 15, 22, and 29-day-old rats. Segments of EEG recorded for 4 hours were analyzed by means of fast Fourier transformation. The sleep-wake activity stages were determined. The developments in the neocortical and hippocampal EEG activities were characterized by the gradual appearance of adult-like EEG waves and a shift towards higher frequencies in the theta wave range of the hippocampal electrical activity. The power value in the theta range, however, exhibited age-invariant rhythmicities with cycle lengths of about 9.5-11 and 16-22 min. The manifestation of such an age-invariant rhythm can be interpreted as an electrical manifestation of the rest-activity cycle originally described by KLEITMAN25.     

Interrelations of hypocapnia, hypoxia, cerebral blood flow and electrical activity of the brain under voluntary hyperventilation in humans

Changes of different physiological parameters in human caused by hyperventilation of 3-min and longer duration were investigated and correlated. It was found that during 3-min hyperventilation, resulting in 4.5-5 fold increase of the respiration velocity, similar phasing changes of the central and cerebral haemodynamics occurred. The blood flow velocity according to the rheographic data during the hyperventilation first increases, reaching maximum at 1st - 2nd min of the test, and then decreases, reaching minimum at 2nd - 3rd min after it's end, and then slowly increases. Cerebral blood flow velocity during all the 3 min of the hyperventilation in most of the subjects keeps being increased, and after the test - decreased. At the same time transcutaneous pressure of carbon dioxide changes differently - decreases to minimum (approximately 25 mmHg) at the end of the test and then increases, reaching approximately 90% of the background level, at 5th min after the end of the test. Oxygen saturation of the blood during the test is found to be 98-100% and decreases to 90% at 5th min after it's end, which in overall with cerebral blood flow decrease appears to be the factor of the brain's hypoxia. In different subjects "mirror" changes of the EEG spectral power of different EEG ranges in relation to transcutaneous pressure of carbon dioxide dynamics were revealed by the hyperventilation. Taking into account the factors of duration or recurrence of the hyperventilation is important for the understanding the interrelations of cerebral haemodynamics, hypocapnia, hypoxia and electrical activity of the brain. It was found that after the recurrent hyperventilation of increasing amount (several times in hour by 3 min) cerebral blood flow might decrease markedly against the background of relatively small changes of electrical activity of the brain. The discussing of the data presented in the paper is carried out from the point of view of important role of tissue oxygen utilization mechanisms of the brain in adaptation to hypoxia and hypocapnia.     

Spectral analysis of spatial series of oceanographic variables

Time series of fluorescence, temperature, concentration of nitrite, and of nitrate+nitrite, obtained in the upwelling zone of northwest Africa, have been analysed by power spectral techniques, after application of a first difference filter. In three of the runs, coherence between fluorescence and temperature was significant at all frequencies lower than 0.04–0.13 cycles/min, while in another three runs, coherences showed a drop at low frequencies. Coherences between the remaining pairs of variables were significant at the lower frequencies studied in most of the cases. Significant coherences between nitrate+nitrite and temperature were found at wider frequency ranges than for fluorescence and temperature. Nitrite showed higher coherences with fluorescence and lower ones with temperature than nitrate+nitrite, as would be expected from the involvement of phytoplankton in the production of nitrite. In view of the results, some points concerning coherence between fluorescence and physical variables, as represented by temperature, are discussed.     

Alterations in protein kinase activity following exposure of cultured human lymphocytes to modulated microwave fields

Cultures of human tonsil lymphocytes were exposed in a Crawford cell to a 450-MHz field (peak envelope intensity 1.0 mW/cm2), sinusoidally amplitude modulated (depth 80%) at frequencies between 3 and 100 Hz for periods up to 60 min. The Crawford cell was housed in a temperature-controlled chamber (35 degrees C) and control cultures were placed in the same chamber. Activity of cAMP-dependent protein kinase relative to controls remained unaltered by fields modulated at 16 or 60 Hz with exposures of 15, 30, and 60 min. By contrast, total non-cAMP-dependent kinase activity fell to less than 50% of unexposed control levels after 15 and 30 min exposures, but, despite continuing field exposure, returned to control or preexposure levels by 45 and 60 min. A smaller reduction (20-25%) also occurred with 60-Hz modulation and was also restricted to exposure durations of 15 and 30 min. CW 450-MHz fields were without effect. Reduced enzyme activity occurred with 16-, 40-, and 60-Hz modulation frequencies, but not with 3-, 6-, 80-, or 100-Hz modulation. The specific identity of this kinase is unknown. This rapid but transient reduction in lymphocyte protein kinase activity restricted to modulation frequencies between 16 and 60 Hz and to less than 30 min exposure is consistent with "windowing" with respect to modulation frequency and exposure duration.     

Resting membrane potential as a marker of apoptosis: studies on Xenopus oocytes microinjected with cytochrome c

Observation of the electrical potential difference across the cell membrane is described as a new method for monitoring apoptosis of a single cell. The resting membrane potential (DeltaPsi) of Xenopus oocytes has been recorded in real time following microinjection of cytochrome c. Soon after microinjection, DeltaPsi becomes less negative and attains a new constant value with a half time, t(m), of about 35 (+ /- 5) min at all cytochrome c concentrations greater than 1 microM. The cytosol extract of cytochrome c-injected oocytes shows DEVD proteolytic activity characteristic of aspartate specific proteases, implicating an apoptotic death pathway. In response to the delivery of cytochrome c into the cytosol, caspases are activated within 7 min while the changes in DeltaPsi begin to occur after about 30 min. The method described here will be potentially useful to assess the effectiveness of cell death regulators and modulators of synthetic and biological origin, and the results presented shed light on the currently debated issue of the importance of the redox state of cytochrome c in the initiation of apoptosis.     

Electrophysiological study of hypothalamic neurons and gonadotropin regulation in rhesus monkey (author's transl)]

The electrical activity of various hypothalamic areas was recorded in anesthetized (sodium pentobartital) (n = 3) and unanesthetized (n = 3) ovariectomized rhesus monkeys. The plasma gonadotropin levels of the animals during the recording sessions were obtained by a chronic cardiac catheter. 1. Sodium pentobarbital greatly affected the electrical activity of most hypothalamic neurons (84%). The mean spontaneous electrical unit activity of neurons in the unanesthetized animals (n = 30) was 1.5 spike/sec. This value decreased to 0.1 spike/sec in the anesthetized group (n = 30). However, a small number of hypothalamic neurons were insensitive to the anaesthetic. 2. The multiunit electrical activity recorded in the median eminence showed marked periodic increases, about 200 sec before LH was observed to rise in the plasma (10/12). This increased firing lasted about 10 min (Fig. 1A). 3. In a few cases (2/12), however, increased firing was not associated with LH release. Since, in this area, multiunit activity represents the summation of a large number of axon terminals, the release of a hypothalamic hormone other than Gn-RH is put foreward as a possible hypothesis. 4. Of 51 neurons recorded in various hypothalamic areas, 3 showed periodic increases of electrical unit activity which corresponded to a rise in plasma LH levels (Fig. 1 B). These neurons are located in the arcuate area. 5. These results are consistent with the hypothesis of a relation between the electrical activity of some hypothalamic neurons and the periodical LH discharges observed in the ovariectomized rhesus monkey.     

Gastroduodenal electric activity, in situ, during anesthesia and recovery. Study in chronic electrode-carrying rats

The effect of anaesthesia (sodium pentobarbital, two various doses) was studied in the rat with chronic gastric and duodenal electrodes. Gastric and duodenal electrical activity was recorded in pre- and peranesthesia period. All rhythmic slow and fast components are slowed in the same condition of time when an important decrease of central temperature is observed (external controlled temperature 22 degrees C). Gastric slow wave (650 microV, frequency normal level 5.6 c/min) decreases about 40% in 180 min. The waking arise after 5h30, 1h30 before the complete recuperation of the previous rhythm. For half dose conditions, gastric slow wave frequency decreases about 30% in 30 min; waking up occurs in 90 min. Gastric emptying complex observed previously. Is only observed during 20-30 min of the initial period of the anaesthesia at 50 mg/kg, and throughout the anaesthesia at 25 mg/kg.     

Effects of differential pulse frequencies of chicken gonadotrophin-releasing hormone-I (cGnRH-I) on laying hen gonadotrope responses in vitro

Abstract

The aim of this work was to determine the effects of cGnRH I pulse frequencies on FSH and LH release and the changes in features and number of cultured laying hen FSH-cells and LH-cells in vitro. Primary adenohypophyseal cell cultures taken from laying hens were stimulated by four 5 min pulses using 1 or 10 nM cGnRH, administered with interpulses between pulses at 15, 30 or 60 min. Pulse frequencies and dose dependent effects were examined in six separate experiments including two controls. After the last interpulse time, the supernatants were collected and stored at ?70° C until the performance of an indirect enzyme-linked immunosorbent assay (ELISA) using chicken LH and chicken FSH antisera at 1:1000 and 1:2000 dilutions, respectively. Supernatants were coated in duplicate on the inner surface of Immulon 2 plates and later blocked with the optimal solutions. They were incubated with each antiserum and subsequently with isotype-specific peroxidase-labeled anti-rabbit antibodies. Hydrogen peroxide/o-phenylenediamine was added as substrate/chromogen and the optical density (OD) was determined at 492 nm. The ABC immunocytochemical method was performed to characterize and re-count the gonadotropes employing anti-chicken FSH and anti-chicken LH as primary antibodies. The number of FSH-LH cells was obtained using stereological analysis and the data were statistically processed. The ODs obtained for each anti-hormone were compared with the control groups and with each other. Significant differences were found in number of aggregated-positive LH cells, which decreased with 1 nM cGnRH-I, 15 vs. 30 min pulses, increased with 30 vs. 60 min pulses, and also with 10 nM cGnRH-I, 30 vs. 60 min pulses. Aggregated positive FSH cells, however, did not show significant differences in percentage at any GnRH dose or pulse frequencies, but did show activity at low pulse frequencies of 15 and 30 min. The results suggest that LH cells varied in percentage in a dose dependent manner at higher pulse frequency (15 min) and were dose independent at low pulse frequency (60 min) and showed inactive features; while FSH cell numbers were unaffected showing features of activity at low pulse frequencies. High and moderate pulse frequencies of cGnRH-I (15-30 min) increased the FSH release in dose independent manner without changes in features or percentage of FSH cells. Low pulse frequency (60 min) of cGnRH-I increased LH release dose independently disminished LH cell percentage and showed changes in cells’ features. These results in avian cells showed differences in responses to GnRH pulse frequencies from those reported earlier in mammals.